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IETF RFC 3253
Versioning Extensions to WebDAV (Web Distributed Authoring and Versioning)
Last modified on Monday, March 4th, 2002
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Network Working Group G. Clemm
Request for Comments: 3253 Rational Software
Category: Standards Track J. Amsden
T. Ellison
IBM
C. Kaler
Microsoft
J. Whitehead
U.C. Santa Cruz
March 2002
Versioning Extensions to WebDAV
(Web Distributed Authoring and Versioning)
 Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright © The Internet Society (2002). All Rights Reserved.
Abstract
This document specifies a set of methods, headers, and resource types
that define the WebDAV (Web Distributed Authoring and Versioning)
versioning extensions to the HTTP/1.1 protocol. WebDAV versioning
will minimize the complexity of clients that are capable of
interoperating with a variety of versioning repository managers, to
facilitate widespread deployment of applications capable of utilizing
the WebDAV Versioning services. WebDAV versioning includes automatic
versioning for versioning-unaware clients, version history
management, workspace management, baseline management, activity
management, and URL namespace versioning.
Table of Contents
1 Introduction.................................................... 6
1.1 Relationship to WebDAV........................................ 7
1.2 Notational Conventions........................................ 8
1.3 Terms......................................................... 8
1.4 Property Values............................................... 11
1.4.1 Initial Property Value..................................... 11
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RFC 3253 Versioning Extensions to WebDAV March 2002
1.4.2 Protected Property Value................................... 12
1.4.3 Computed Property Value.................................... 12
1.4.4 Boolean Property Value..................................... 12
1.4.5 DAV:href Property Value.................................... 12
1.5 DAV Namespace XML Elements.................................... 12
1.6 Method Preconditions and Postconditions....................... 12
1.6.1 Example - CHECKOUT request................................. 13
1.7 Clarification of COPY Semantics with Overwrite:T.............. 13
1.8 Versioning Methods and Write Locks............................ 14
2 Basic Versioning Features....................................... 14
2.1 Basic Versioning Packages..................................... 14
2.2 Basic Versioning Semantics.................................... 16
2.2.1 Creating a Version-Controlled Resource..................... 16
2.2.2 Modifying a Version-Controlled Resource.................... 17
2.2.3 Reporting.................................................. 19
3 Version-Control Feature......................................... 20
3.1 Additional Resource Properties................................ 20
3.1.1 DAV:comment................................................ 20
3.1.2 DAV:creator-displayname.................................... 20
3.1.3 DAV:supported-method-set (protected)....................... 20
3.1.4 DAV:supported-live-property-set (protected)................ 21
3.1.5 DAV:supported-report-set (protected)....................... 21
3.2 Version-Controlled Resource Properties........................ 21
3.2.1 DAV:checked-in (protected)................................. 21
3.2.2 DAV:auto-version........................................... 22
3.3 Checked-Out Resource Properties............................... 22
3.3.1 DAV:checked-out (protected)................................ 23
3.3.2 DAV:predecessor-set........................................ 23
3.4 Version Properties............................................ 23
3.4.1 DAV:predecessor-set (protected)............................ 23
3.4.2 DAV:successor-set (computed)............................... 23
3.4.3 DAV:checkout-set (computed)................................ 23
3.4.4 DAV:version-name (protected)............................... 24
3.5 VERSION-CONTROL Method........................................ 24
3.5.1 Example - VERSION-CONTROL.................................. 25
3.6 REPORT Method................................................. 25
3.7 DAV:version-tree Report....................................... 26
3.7.1 Example - DAV:version-tree Report.......................... 27
3.8 DAV:expand-property Report.................................... 29
3.8.1 Example - DAV:expand-property.............................. 30
3.9 Additional OPTIONS Semantics.................................. 31
3.10 Additional PUT Semantics..................................... 31
3.11 Additional PROPFIND Semantics................................ 32
3.12 Additional PROPPATCH Semantics............................... 33
3.13 Additional DELETE Semantics.................................. 33
3.14 Additional COPY Semantics.................................... 34
3.15 Additional MOVE Semantics.................................... 34
3.16 Additional UNLOCK Semantics.................................. 35
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RFC 3253 Versioning Extensions to WebDAV March 2002
4 Checkout-In-Place Feature....................................... 35
4.1 Additional Version Properties................................. 35
4.1.1 DAV:checkout-fork.......................................... 36
4.1.2 DAV:checkin-fork........................................... 36
4.2 Checked-Out Resource Properties............................... 36
4.2.1 DAV:checkout-fork.......................................... 36
4.2.2 DAV:checkin-fork........................................... 37
4.3 CHECKOUT Method............................................... 37
4.3.1 Example - CHECKOUT......................................... 38
4.4 CHECKIN Method................................................ 38
4.4.1 Example - CHECKIN.......................................... 40
4.5 UNCHECKOUT Method............................................. 40
4.5.1 Example - UNCHECKOUT....................................... 41
4.6 Additional OPTIONS Semantics.................................. 42
5 Version-History Feature......................................... 42
5.1 Version History Properties.................................... 42
5.1.1 DAV:version-set (protected)................................ 42
5.1.2 DAV:root-version (computed)................................ 42
5.2 Additional Version-Controlled Resource Properties............. 42
5.2.1 DAV:version-history (computed)............................. 43
5.3 Additional Version Properties................................. 43
5.3.1 DAV:version-history (computed)............................. 43
5.4 DAV:locate-by-history Report.................................. 43
5.4.1 Example - DAV:locate-by-history Report..................... 44
5.5 Additional OPTIONS Semantics.................................. 45
5.6 Additional DELETE Semantics................................... 46
5.7 Additional COPY Semantics..................................... 46
5.8 Additional MOVE Semantics..................................... 46
5.9 Additional VERSION-CONTROL Semantics.......................... 46
5.10 Additional CHECKIN Semantics................................. 47
6 Workspace Feature............................................... 47
6.1 Workspace Properties.......................................... 48
6.1.1 DAV:workspace-checkout-set (computed)...................... 48
6.2 Additional Resource Properties................................ 48
6.2.1 DAV:workspace (protected).................................. 48
6.3 MKWORKSPACE Method............................................ 48
6.3.1 Example - MKWORKSPACE...................................... 49
6.4 Additional OPTIONS Semantics.................................. 49
6.4.1 Example - OPTIONS.......................................... 51
6.5 Additional DELETE Semantics................................... 51
6.6 Additional MOVE Semantics..................................... 52
6.7 Additional VERSION-CONTROL Semantics.......................... 52
6.7.1 Example - VERSION-CONTROL.................................. 53
7 Update Feature.................................................. 53
7.1 UPDATE Method................................................. 53
7.1.1 Example - UPDATE........................................... 55
7.2 Additional OPTIONS Semantics.................................. 55
8 Label Feature................................................... 56
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RFC 3253 Versioning Extensions to WebDAV March 2002
8.1 Additional Version Properties................................. 56
8.1.1 DAV:label-name-set (protected)............................. 56
8.2 LABEL Method.................................................. 56
8.2.1 Example - Setting a label.................................. 58
8.3 Label Header.................................................. 58
8.4 Additional OPTIONS Semantics.................................. 59
8.5 Additional GET Semantics...................................... 59
8.6 Additional PROPFIND Semantics................................. 59
8.7 Additional COPY Semantics..................................... 60
8.8 Additional CHECKOUT Semantics................................. 60
8.9 Additional UPDATE Semantics................................... 61
9 Working-Resource Feature........................................ 62
9.1 Additional Version Properties................................. 62
9.1.1 DAV:checkout-fork.......................................... 62
9.1.2 DAV:checkin-fork........................................... 63
9.2 Working Resource Properties................................... 63
9.2.1 DAV:auto-update (protected)................................ 63
9.2.2 DAV:checkout-fork.......................................... 63
9.2.3 DAV:checkin-fork........................................... 63
9.3 CHECKOUT Method (applied to a version)........................ 63
9.3.1 Example - CHECKOUT of a version............................ 65
9.4 CHECKIN Method (applied to a working resource)................ 65
9.4.1 Example - CHECKIN of a working resource.................... 66
9.5 Additional OPTIONS Semantics.................................. 67
9.6 Additional COPY Semantics..................................... 67
9.7 Additional MOVE Semantics..................................... 67
10 Advanced Versioning Features.................................. 67
10.1 Advanced Versioning Packages................................. 68
10.2 Advanced Versioning Terms.................................... 68
11 MERGE Feature................................................. 70
11.1 Additional Checked-Out Resource Properties................... 70
11.1.1 DAV:merge-set............................................. 70
11.1.2 DAV:auto-merge-set........................................ 71
11.2 MERGE Method................................................. 71
11.2.1 Example - MERGE........................................... 74
11.3 DAV:merge-preview Report..................................... 75
11.3.1 Example - DAV:merge-preview Report........................ 76
11.4 Additional OPTIONS Semantics................................. 77
11.5 Additional DELETE Semantics.................................. 77
11.6 Additional CHECKIN Semantics................................. 77
12 Baseline Feature.............................................. 77
12.1 Version-Controlled Configuration Properties.................. 78
12.1.1 DAV:baseline-controlled-collection (protected)............ 78
12.2 Checked-Out Configuration Properties......................... 78
12.2.1 DAV:subbaseline-set....................................... 78
12.3 Baseline Properties.......................................... 78
12.3.1 DAV:baseline-collection (protected)....................... 79
12.3.2 DAV:subbaseline-set (protected)........................... 79
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RFC 3253 Versioning Extensions to WebDAV March 2002
12.4 Additional Resource Properties............................... 79
12.4.1 DAV:version-controlled-configuration (computed)........... 79
12.5 Additional Workspace Properties.............................. 80
12.5.1 DAV:baseline-controlled-collection-set (computed)......... 80
12.6 BASELINE-CONTROL Method...................................... 80
12.6.1 Example - BASELINE-CONTROL................................ 82
12.7 DAV:compare-baseline Report.................................. 84
12.7.1 Example - DAV:compare-baseline Report..................... 85
12.8 Additional OPTIONS Semantics................................. 86
12.9 Additional MKCOL Semantics................................... 86
12.10 Additional COPY Semantics................................... 86
12.11 Additional CHECKOUT Semantics............................... 86
12.12 Additional CHECKIN Semantics................................ 86
12.13 Additional UPDATE Semantics................................. 87
12.14 Additional MERGE Semantics.................................. 89
13 Activity Feature.............................................. 90
13.1 Activity Properties.......................................... 91
13.1.1 DAV:activity-version-set (computed)....................... 91
13.1.2 DAV:activity-checkout-set (computed)...................... 92
13.1.3 DAV:subactivity-set....................................... 92
13.1.4 DAV:current-workspace-set (computed)...................... 92
13.2 Additional Version Properties................................ 92
13.2.1 DAV:activity-set.......................................... 93
13.3 Additional Checked-Out Resource Properties................... 93
13.3.1 DAV:unreserved............................................ 93
13.3.2 DAV:activity-set.......................................... 93
13.4 Additional Workspace Properties.............................. 93
13.4.1 DAV:current-activity-set.................................. 94
13.5 MKACTIVITY Method............................................ 94
13.5.1 Example - MKACTIVITY...................................... 95
13.6 DAV:latest-activity-version Report........................... 95
13.7 Additional OPTIONS Semantics................................. 96
13.8 Additional DELETE Semantics.................................. 96
13.9 Additional MOVE Semantics.................................... 97
13.10 Additional CHECKOUT Semantics............................... 97
13.10.1 Example - CHECKOUT with an activity...................... 98
13.11 Additional CHECKIN Semantics................................ 99
13.12 Additional MERGE Semantics.................................. 99
14 Version-Controlled-Collection Feature.........................100
14.1 Version-Controlled Collection Properties.....................102
14.1.1 DAV:eclipsed-set (computed)...............................102
14.2 Collection Version Properties................................103
14.2.1 DAV:version-controlled-binding-set (protected)............103
14.3 Additional OPTIONS Semantics.................................103
14.4 Additional DELETE Semantics..................................103
14.5 Additional MKCOL Semantics...................................104
14.6 Additional COPY Semantics....................................104
14.7 Additional MOVE Semantics....................................104
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RFC 3253 Versioning Extensions to WebDAV March 2002
14.8 Additional VERSION-CONTROL Semantics.........................104
14.9 Additional CHECKOUT Semantics................................105
14.10 Additional CHECKIN Semantics................................105
14.11 Additional UPDATE and MERGE Semantics.......................106
15 Internationalization Considerations...........................106
16 Security Considerations.......................................107
16.1 Auditing and Traceability....................................107
16.2 Increased Need for Access Control............................108
16.3 Security Through Obscurity...................................108
16.4 Denial of Service............................................108
17 IANA Considerations...........................................109
18 Intellectual Property.........................................109
19 Acknowledgements..............................................109
20 References....................................................110
Appendix A - Resource Classification..............................111
A.1 DeltaV-Compliant Unmapped URL.................................111
A.2 DeltaV-Compliant Resource.....................................111
A.3 DeltaV-Compliant Collection...................................112
A.4 Versionable Resource..........................................112
A.5 Version-Controlled Resource...................................112
A.6 Version.......................................................113
A.7 Checked-In Version-Controlled Resource........................113
A.8 Checked-Out Resource..........................................113
A.9 Checked-Out Version-Controlled Resource.......................114
A.10 Working Resource.............................................114
A.11 Version History..............................................114
A.12 Workspace....................................................115
A.13 Activity.....................................................115
A.14 Version-Controlled Collection................................115
A.15 Collection Version...........................................115
A.16 Version-Controlled Configuration.............................116
A.17 Baseline.....................................................116
A.18 Checked-Out Version-Controlled Configuration.................116
Authors' Addresses................................................117
Full Copyright Statement..........................................118
1 Introduction
This document specifies a set of methods, headers, and properties
that define the WebDAV (Web Distributed Authoring and Versioning)
versioning extensions to the HTTP/1.1 protocol. Versioning is
concerned with tracking and accessing the history of important states
of a web resource, such as a standalone web page. The benefits of
versioning in the context of the worldwide web include:
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RFC 3253 Versioning Extensions to WebDAV March 2002
- A resource has an explicit history and a persistent identity
across the various states it has had during the course of that
history. It allows browsing through past and alternative versions
of a resource. Frequently the modification and authorship history
of a resource is critical information in itself.
- Resource states (versions) are given stable names that can support
externally stored links for annotation and link server support.
Both annotation and link servers frequently need to store stable
references to portions of resources that are not under their
direct control. By providing stable states of resources, version
control systems allow not only stable pointers into those
resources, but also well defined methods to determine the
relationships of those states of a resource.
WebDAV Versioning defines both basic and advanced versioning
functionality.
Basic versioning allows users to:
- Put a resource under version control
- Determine whether a resource is under version control
- Determine whether a resource update will automatically be captured
as a new version
- Create and access distinct versions of a resource
Advanced versioning provides additional functionality for parallel
development and configuration management of sets of web resources.
This document will first define the properties and method semantics
for the basic versioning features, and then define the additional
properties and method semantics for the advanced versioning features.
An implementer that is only interested in basic versioning should
skip the advanced versioning sections (Section 10 to Section 14).
1.1 Relationship to WebDAV
To maximize interoperability and the use of existing protocol
functionality, versioning support is designed as extensions to the
WebDAV protocol [RFC 2518], which itself is an extension to the HTTP
protocol [RFC 2616]. All method marshalling and postconditions
defined by RFC 2518 and RFC 2616 continue to hold, to ensure that
versioning unaware clients can interoperate successfully with
versioning servers. Although the versioning extensions are designed
to be orthogonal to most aspects of the WebDAV and HTTP protocols, a
clarification to RFC 2518 is required for effective interoperable
versioning. This clarification is described in Section 1.7.
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RFC 3253 Versioning Extensions to WebDAV March 2002
1.2 Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
The term "protected" is placed in parentheses following the
definition of a protected property (see Section 1.4.2).
The term "computed" is placed in parentheses following the definition
of a computed property (see Section 1.4.3).
When an XML element type in the "DAV:" namespace is referenced in
this document outside of the context of an XML fragment, the string
"DAV:" will be prefixed to the element type.
When a method is defined in this document, a list of preconditions
and postconditions will be defined for that method. If the semantics
of an existing method is being extended, a list of additional
preconditions and postconditions will be defined. A precondition or
postcondition is prefixed by a parenthesized XML element type that
identifies that precondition or postcondition (see Section 1.6).
1.3 Terms
This document uses the terms defined in RFC 2616, in RFC 2518, and in
this section. Section 2.2 defines the semantic versioning model
underlying this terminology.
Version Control, Checked-In, Checked-Out
"Version control" is a set of constraints on how a resource can be
updated. A resource under version control is either in a
"checked-in" or "checked-out" state, and the version control
constraints apply only while the resource is in the checked-in
state.
Versionable Resource
A "versionable resource" is a resource that can be put under
version control.
Version-Controlled Resource
When a versionable resource is put under version control, it
becomes a "version-controlled resource". A version-controlled
resource can be "checked out" to allow modification of its content
or dead properties by standard HTTP and WebDAV methods.
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RFC 3253 Versioning Extensions to WebDAV March 2002
Checked-Out Resource
A "checked-out resource" is a resource under version control that
is in the checked-out state.
Version Resource
A "version resource", or simply "version", is a resource that
contains a copy of a particular state (content and dead
properties) of a version-controlled resource. A version is
created by "checking in" a checked-out resource. The server
allocates a distinct new URL for each new version, and this URL
will never be used to identify any resource other than that
version. The content and dead properties of a version never
change.
Version History Resource
A "version history resource", or simply "version history", is a
resource that contains all the versions of a particular version-
controlled resource.
Version Name
A "version name" is a string chosen by the server to distinguish
one version of a version history from the other versions of that
version history. Versions from different version histories may
have the same version name.
Predecessor, Successor, Ancestor, Descendant
When a version-controlled resource is checked out and then
subsequently checked in, the version that was checked out becomes
a "predecessor" of the version created by the checkin. A client
can specify multiple predecessors for a new version if the new
version is logically a merge of those predecessors. When a
version is connected to another version by traversing one or more
predecessor relations, it is called an "ancestor" of that version.
The inverse of the predecessor and ancestor relations are the
"successor" and "descendant" relations. Therefore, if X is a
predecessor of Y, then Y is a successor of X, and if X is an
ancestor of Y, then Y is a descendant of X.
Root Version Resource
The "root version resource", or simply "root version", is the
version in a version history that is an ancestor of every other
version in that version history.
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RFC 3253 Versioning Extensions to WebDAV March 2002
Workspace Resource
A "workspace resource", or simply "workspace", is a collection
that contains at most one version-controlled resource for a given
version history (see Section 6).
Working Resource
A "working resource" is a checked-out resource created by the
server at a server-defined URL when a version (instead of a
version-controlled resource) is checked out. Unlike a checked-out
version-controlled resource, a working resource is deleted when it
is checked in.
Fork, Merge
When a second successor is added to a version, this creates a
"fork" in the version history. When a version is created with
multiple predecessors, this creates a "merge" in the version
history. A server may restrict the version history to be linear
(with no forks or merges), but an interoperable versioning client
should be prepared to deal with both forks and merges in the
version history.
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RFC 3253 Versioning Extensions to WebDAV March 2002
The following diagram illustrates several of the previous
definitions. Each box represents a version and each line between two
boxes represents a predecessor/successor relationship. For example,
it shows V3 is a predecessor of V5, V7 is a successor of V5, V1 is an
ancestor of V4, and V7 is a descendant of V4. It also shows that
there is a fork at version V2 and a merge at version V7.
History of foo.html
+---+
Root Version -------> | | V1
+---+ ^
| |
| |
+---+ |
Version Name ----> V2 | | | Ancestor
+---+ |
/ \ |
/ \ |
+---+ +---+
| | V3 | | V4
^ +---+ +---+
| | | |
Predecessor | | | |
+---+ +---+ |
| | V5 | | V6 | Descendant
+---+ +---+ |
Successor | \ / |
| \ / |
v +---+ v
| | V7
+---+
Label
A "label" is a name that can be used to select a version from a
version history. A label can be assigned by either a client or
the server. The same label can be used in different version
histories.
1.4 Property Values
1.4.1 Initial Property Value
Unless an initial value of a property of a given type is defined by
this document, the initial value of a property of that type is
implementation dependent.
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RFC 3253 Versioning Extensions to WebDAV March 2002
1.4.2 Protected Property Value
When a property of a specific kind of resource is "protected", the
property value cannot be updated on that kind of resource except by a
method explicitly defined as updating that specific property. In
particular, a protected property cannot be updated with a PROPPATCH
request. Note that a given property can be protected on one kind of
resource, but not protected on another kind of resource.
1.4.3 Computed Property Value
When a property is "computed", its value is defined in terms of a
computation based on the content and other properties of that
resource, or even of some other resource. When the semantics of a
method is defined in this document, the effect of that method on
non-computed properties will be specified; the effect of that method
on computed properties will not be specified, but can be inferred
from the computation defined for those properties. A computed
property is always a protected property.
1.4.4 Boolean Property Value
Some properties take a Boolean value of either "false" or "true".
1.4.5 DAV:href Property Value
The DAV:href XML element is defined in RFC 2518, Section 12.3.
1.5 DAV Namespace XML Elements in Request and Response Bodies
Although WebDAV request and response bodies can be extended by
arbitrary XML elements, which can be ignored by the message
recipient, an XML element in the DAV namespace MUST NOT be used in
the request or response body of a versioning method unless that XML
element is explicitly defined in an IETF RFC.
1.6 Method Preconditions and Postconditions
A "precondition" of a method describes the state of the server that
must be true for that method to be performed. A "postcondition" of a
method describes the state of the server that must be true after that
method has been completed. If a method precondition or postcondition
for a request is not satisfied, the response status of the request
MUST be either 403 (Forbidden) if the request should not be repeated
because it will always fail, or 409 (Conflict) if it is expected that
the user might be able to resolve the conflict and resubmit the
request.
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In order to allow better client handling of 403 and 409 responses, a
distinct XML element type is associated with each method precondition
and postcondition of a request. When a particular precondition is
not satisfied or a particular postcondition cannot be achieved, the
appropriate XML element MUST be returned as the child of a top-level
DAV:error element in the response body, unless otherwise negotiated
by the request. In a 207 Multi-Status response, the DAV:error
element would appear in the appropriate DAV:responsedescription
element.
1.6.1 Example - CHECKOUT request with DAV:must-be-checked-in response
>>REQUEST
CHECKOUT /foo.html HTTP/1.1
Host: www.webdav.org
>>RESPONSE
HTTP/1.1 409 Conflict
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:error xmlns:D="DAV:">
<D:must-be-checked-in/>
</D:error>
In this example, the request to CHECKOUT /foo.html fails because
/foo.html is not checked in.
1.7 Clarification of COPY Semantics with Overwrite:T
RFC 2518, Section 8.8.4 states:
"If a resource exists at the destination and the Overwrite header is
"T" then prior to performing the copy the server MUST perform a
DELETE with "Depth: infinity" on the destination resource."
The purpose of this sentence is to ensure that following a COPY, all
destination resources have the same content and dead properties as
the corresponding resources identified by the request-URL (where a
resource with a given name relative to the Destination URL
"corresponds" to a resource with the same name relative to the
request-URL). If at the time of the request, there already is a
resource at the destination that has the same resource type as the
corresponding resource at the request-URL, that resource MUST NOT be
deleted, but MUST be updated to have the content and dead properties
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RFC 3253 Versioning Extensions to WebDAV March 2002
of its corresponding member. If a client wishes all resources at the
destination to be deleted prior to the COPY, it MUST explicitly issue
a DELETE request.
The difference between updating a resource and replacing a resource
with a new resource is especially important when resource history is
being maintained (the former adds to an existing history, while the
latter creates a new history). In addition, locking and access
control constraints might allow you to update a resource, but not
allow you to delete it and create a new one in its place.
Note that this clarification does not apply to a MOVE request. A
MOVE request with Overwrite:T MUST perform the DELETE with
"Depth:infinity" on the destination resource prior to performing the
MOVE.
1.8 Versioning Methods and Write Locks
If a write-locked resource has a non-computed property defined by
this document, the property value MUST NOT be changed by a request
unless the appropriate lock token is included in the request. Since
every method introduced in this document other than REPORT modifies
at least one property defined by this document, every versioning
method other than REPORT is affected by a write lock. In particular,
the method MUST fail with a 423 (Locked) status if the resource is
write-locked and the appropriate token is not specified in an If
request header.
2 Basic Versioning Features
Each basic versioning feature defines extensions to existing HTTP and
WebDAV methods, as well as new resource types, live properties, and
methods.
2.1 Basic Versioning Packages
A server MAY support any combination of versioning features.
However, in order to minimize the complexity of a WebDAV basic
versioning client, a WebDAV basic versioning server SHOULD support
one of the following three "packages" (feature sets):
- Core-Versioning Package: version-control
- Basic-Server-Workspace Package: version-control, workspace,
version-history, checkout
- Basic-Client-Workspace Package: version-control, working-
resource, update, label
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The core-versioning package supports linear versioning by both
versioning-aware and versioning-unaware clients. A versioning-aware
client can use reports and properties to access previous versions of
a version-controlled resource.
The basic workspace packages support parallel development of
version-controlled resources. Each client has its own configuration
of the shared version-controlled resources, and can make changes to
its configuration without disturbing that of another client.
In the basic-server-workspace package, all persistent state is
maintained on the server. Each client has its own workspace resource
allocated on the server, where each workspace identifies a
configuration of the shared version-controlled resources. Each
client makes changes to its workspace, and can transfer changes when
appropriate from one workspace to another. The server workspace
package is appropriate for clients with no local persistent state, or
for clients that wish to expose their working configurations to other
clients.
In the basic-client-workspace package, each client maintains in local
persistent storage the state for its configuration of the shared
version-controlled resources. When a client is ready to make its
changes visible to other clients, it allocates a set of "working
resources" on the server, updates the content and dead properties of
these working resources, and then uses the set of working resources
to update the version-controlled resources. The working resources
are used, instead of directly updating the version-controlled
resources, so that sets of consistent updates can be prepared in
parallel by multiple clients. Also, a working resource allows a
client to prepare a single update that requires multiple server
requests (e.g. updating both the content and dead properties of a
resource requires both a PUT and a PROPPATCH). The client workspace
package simplifies the server implementation by requiring each client
to maintain its own namespace, but this requires that the clients
have local persistent state, and does not allow clients to expose
their working configurations to other clients.
A server that supports both basic workspace packages will
interoperate with all basic versioning clients.
Clemm, et al. Standards Track PAGE 15
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2.2 Basic Versioning Semantics
2.2.1 Creating a Version-Controlled Resource
In order to track the history of the content and dead properties of a
versionable resource, a user can put the resource under version
control with a VERSION-CONTROL request. A VERSION-CONTROL request
performs three distinct operations:
1) It creates a new "version history resource". In basic versioning,
a version history resource is not assigned a URL, and hence is not
visible in the http scheme URL space. However, when the version-
history feature (see Section 5) is supported, this changes, and
each version history resource is assigned a new distinct and
unique server-defined URL.
2) It creates a new "version resource" and adds it to the new version
history resource. The body and dead properties of the new version
resource are a copy of those of the versionable resource.
The server assigns the new version resource a new distinct and
unique URL.
3) It converts the versionable resource into a "version-controlled
resource". The version-controlled resource continues to be
identified by the same URL that identified it as a versionable
resource. As part of this conversion, it adds a DAV:checked-in
property, whose value contains the URL of the new version
resource.
Note that a versionable resource and a version-controlled resource
are not new types of resources (i.e. they introduce no new
DAV:resourcetype), but rather they are any type of resource that
supports the methods and live properties defined for them in this
document, in addition to all the methods and live properties implied
by their DAV:resourcetype. For example, a collection (whose
DAV:resourcetype is DAV:collection) is a versionable resource if it
supports the VERSION-CONTROL method, and is a version-controlled
resource if it supports the version-controlled resource methods and
live properties.
In the following example, foo.html is a versionable resource that is
put under version control. After the VERSION-CONTROL request
succeeds, there are two additional resources: a new version history
resource and a new version resource in that version history. The
versionable resource is converted into a version-controlled resource,
whose DAV:checked-in property identifies the new version resource.
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The content and dead properties of a resource are represented by the
symbol appearing inside the box for that resource (e.g., "S1" in the
following example).
===VERSION-CONTROL==>
| +----+ version
| version- | | history
versionable | controlled +----+ resource
resource | resource |
/foo.html | /foo.html |
| v
+----+ | +----+ checked-in +----+ version
| S1 | | | S1 |----------->| S1 | resource
+----+ | +----+ +----+ /his/73/ver/1
Thus, whereas before the VERSION-CONTROL request there was only one,
non-version-controlled resource, after VERSION-CONTROL there are
three separate, distinct resources, each containing its own state and
properties: the version-controlled resource, the version resource,
and the version history resource. Since the version-controlled
resource and the version resource are separate, distinct resources,
when a method is applied to a version-controlled resource, it is only
applied to that version-controlled resource, and is not applied to
the version resource that is currently identified by the
DAV:checked-in property of that version-controlled resource.
Although the content and dead properties of a checked-in version-
controlled resource are required to be the same as those of its
current DAV:checked-in version, its live properties may differ. An
implementation may optimize storage by retrieving the content and
dead properties of a checked-in version-controlled resource from its
current DAV:checked-in version rather than storing them in the
version-controlled resource, but this is just an implementation
optimization.
Normally, a resource is placed under version control with an explicit
VERSION-CONTROL request. A server MAY automatically place every new
versionable resource under version control. In this case, the
resulting state on the server MUST be the same as if the client had
explicitly applied a VERSION-CONTROL request to the versionable
resource.
2.2.2 Modifying a Version-Controlled Resource
In order to use methods like PUT and PROPPATCH to directly modify the
content or dead properties of a version-controlled resource, the
version-controlled resource must first be checked out. When the
checked-out resource is checked in, a new version is created in the
Clemm, et al. Standards Track PAGE 17
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version history of that version-controlled resource. The version
that was checked out is remembered as the predecessor of the new
version.
The DAV:auto-version property (see Sections 3.2.2) of a checked-in
version-controlled resource determines how it responds to a method
that attempts to modify its content or dead properties. Possible
responses include:
- Fail the request. The resource requires an explicit CHECKOUT
request for it to be modified (see Sections 4 and 9.2.1).
- Automatically checkout the resource, perform the modification, and
automatically checkin the resource. This ensures that every state
of the resource is tracked by the server, but can result in an
excessive number of versions being created.
- Automatically checkout the resource, perform the modification, and
then if the resource is not write-locked, automatically checkin
the resource. If the resource is write-locked, it remains
checked-out until the write-lock is removed (either explicitly
through a subsequent UNLOCK request or implicitly through a time-
out of the write-lock). This helps a locking client avoid the
proliferation of versions, while still allowing a non-locking
client to update the resource.
- Automatically checkout the resource, perform the modification, and
then leave the resource checked out. If the resource is write-
locked, it will be automatically checked in when the write-lock is
removed, but an explicit CHECKIN operation (see Section 4.4) is
required for a non-write-locked resource. This minimizes the
number of new versions that will be created by a versioning
unaware client, but only a versioning aware client can create new
versions of a non-write-locked resource.
- Fail the request unless the resource is write-locked. If it is
write-locked, automatically checkout the resource and perform the
modification. The resource is automatically checked in when the
write-lock is removed. This minimizes the number of new versions
that will be created by a versioning unaware client, but never
automatically checks out a resource that will not subsequently be
automatically checked in.
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The following diagram illustrates the effect of the checkout/checkin
process on a version-controlled resource and its version history.
The symbol inside a box (S1, S2, S3) represents the current content
and dead properties of the resource represented by that box. The
symbol next to a box (V1, V2, V3) represents the URL for that
resource.
===checkout==> ===PUT==> ===checkin==>
/foo.html (version-controlled resource)
+----+ | +----+ | +----+ | +----+
| S2 | | | S2 | | | S3 | | | S3 |
+----+ | +----+ | +----+ | +----+
Checked-In=V2|Checked-Out=V2|Checked-Out=V2|Checked-In=V3
/his/73 (version history for /foo.html)
+----+ | +----+ | +----+ | +----+
| S1 | V1 | | S1 | V1 | | S1 | V1 | | S1 | V1
+----+ | +----+ | +----+ | +----+
| | | | | | |
| | | | | | |
+----+ | +----+ | +----+ | +----+
| S2 | V2 | | S2 | V2 | | S2 | V2 | | S2 | V2
+----+ | +----+ | +----+ | +----+
| | | |
| | | |
| | | +----+
| | | | S3 | V3
| | | +----+
Note that a version captures only a defined subset of the state of a
resource. In particular, a version of a basic resource captures its
content and dead properties, but not its live properties.
2.2.3 Reporting
Some versioning information about a resource requires that parameters
be specified along with that request for information. Included in
basic versioning is the required support for an extensible reporting
mechanism, which includes a REPORT method as well as a live property
for determining what reports are supported by a particular resource.
The REPORT method is required by versioning, but it can be used in
non-versioning WebDAV extensions.
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To allow a client to query the properties of all versions in the
version history of a specified version-controlled resource, basic
versioning provides the DAV:version-tree report (see Section 3.7). A
more powerful version history reporting mechanism is provided by
applying the DAV:expand-property report (see Section 3.8) to a
version history resource (see Section 5).
3 Version-Control Feature
The version-control feature provides support for putting a resource
under version control, creating an associated version-controlled
resource and version history resource as described in Section 2.2.1.
A server indicates that it supports the version-control feature by
including the string "version-control" as a field in the DAV header
in the response to an OPTIONS request. The version-control feature
MUST be supported if any other versioning feature is supported.
3.1 Additional Resource Properties
The version-control feature introduces the following REQUIRED
properties for any WebDAV resource.
3.1.1 DAV:comment
This property is used to track a brief comment about a resource that
is suitable for presentation to a user. The DAV:comment of a version
can be used to indicate why that version was created.
<!ELEMENT comment (#PCDATA)>
PCDATA value: string
3.1.2 DAV:creator-displayname
This property contains a description of the creator of the resource
that is suitable for presentation to a user. The DAV:creator-
displayname of a version can be used to indicate who created that
version.
<!ELEMENT creator-displayname (#PCDATA)>
PCDATA value: string
3.1.3 DAV:supported-method-set (protected)
This property identifies the methods that are supported by the
resource. A method is supported by a resource if there is some state
of that resource for which an application of that method will
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successfully satisfy all postconditions of that method, including any
additional postconditions added by the features supported by that
resource.
<!ELEMENT supported-method-set (supported-method*)>
<!ELEMENT supported-method ANY>
<!ATTLIST supported-method name NMTOKEN #REQUIRED>
name value: a method name
3.1.4 DAV:supported-live-property-set (protected)
This property identifies the live properties that are supported by
the resource. A live property is supported by a resource if that
property has the semantics defined for that property. The value of
this property MUST identify all live properties defined by this
document that are supported by the resource, and SHOULD identify all
live properties that are supported by the resource.
<!ELEMENT supported-live-property-set (supported-live-property*)>
<!ELEMENT supported-live-property name>
<!ELEMENT prop ANY>
ANY value: a property element type
3.1.5 DAV:supported-report-set (protected)
This property identifies the reports that are supported by the
resource.
<!ELEMENT supported-report-set (supported-report*)>
<!ELEMENT supported-report report>
<!ELEMENT report ANY>
ANY value: a report element type
3.2 Version-Controlled Resource Properties
The version-control feature introduces the following REQUIRED
properties for a version-controlled resource.
3.2.1 DAV:checked-in (protected)
This property appears on a checked-in version-controlled resource,
and identifies a version that has the same content and dead
properties as the version-controlled resource. This property is
removed when the resource is checked out, and then added back
(identifying a new version) when the resource is checked back in.
<!ELEMENT checked-in (href)>
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3.2.2 DAV:auto-version
If the DAV:auto-version value is DAV:checkout-checkin, when a
modification request (such as PUT/PROPPATCH) is applied to a
checked-in version-controlled resource, the request is automatically
preceded by a checkout and followed by a checkin operation.
If the DAV:auto-version value is DAV:checkout-unlocked-checkin, when
a modification request is applied to a checked-in version-controlled
resource, the request is automatically preceded by a checkout
operation. If the resource is not write-locked, the request is
automatically followed by a checkin operation.
If the DAV:auto-version value is DAV:checkout, when a modification
request is applied to a checked-in version-controlled resource, the
request is automatically preceded by a checkout operation.
If the DAV:auto-version value is DAV:locked-checkout, when a
modification request is applied to a write-locked checked-in
version-controlled resource, the request is automatically preceded by
a checkout operation.
If an update to a write-locked checked-in resource is automatically
preceded by a checkout of that resource, the checkout is associated
with the write lock. When this write lock is removed (e.g. from an
UNLOCK or a lock timeout), if the resource has not yet been checked
in, the removal of the write lock is automatically preceded by a
checkin operation.
A server MAY refuse to allow the value of the DAV:auto-version
property to be modified, or MAY only support values from a subset of
the valid values.
<!ELEMENT auto-version (checkout-checkin | checkout-unlocked-checkin
| checkout | locked-checkout)? >
<!ELEMENT checkout-checkin EMPTY>
<!ELEMENT checkout-unlocked-checkin EMPTY>
<!ELEMENT checkout EMPTY>
<!ELEMENT locked-checkout EMPTY>
3.3 Checked-Out Resource Properties
The version-control feature introduces the following REQUIRED
properties for a checked-out resource.
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3.3.1 DAV:checked-out (protected)
This property identifies the version that was identified by the
DAV:checked-in property at the time the resource was checked out.
This property is removed when the resource is checked in.
<!ELEMENT checked-out (href)>
3.3.2 DAV:predecessor-set
This property determines the DAV:predecessor-set property of the
version that results from checking in this resource.
A server MAY reject attempts to modify the DAV:predecessor-set of a
version-controlled resource.
<!ELEMENT predecessor-set (href+)>
3.4 Version Properties
The version-control feature introduces the following REQUIRED
properties for a version.
3.4.1 DAV:predecessor-set (protected)
This property identifies each predecessor of this version. Except
for the root version, which has no predecessors, each version has at
least one predecessor.
<!ELEMENT predecessor-set (href*)>
3.4.2 DAV:successor-set (computed)
This property identifies each version whose DAV:predecessor-set
identifies this version.
<!ELEMENT successor-set (href*)>
3.4.3 DAV:checkout-set (computed)
This property identifies each checked-out resource whose
DAV:checked-out property identifies this version.
<!ELEMENT checkout-set (href*)>
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3.4.4 DAV:version-name (protected)
This property contains a server-defined string that is different for
each version in a given version history. This string is intended for
display for a user, unlike the URL of a version, which is normally
only used by a client and not displayed for a user.
<!ELEMENT version-name (#PCDATA)>
PCDATA value: string
3.5 VERSION-CONTROL Method
A VERSION-CONTROL request can be used to create a version-controlled
resource at the request-URL. It can be applied to a versionable
resource or to a version-controlled resource.
If the request-URL identifies a versionable resource, a new version
history resource is created, a new version is created whose content
and dead properties are copied from the versionable resource, and the
resource is given a DAV:checked-in property that is initialized to
identify this new version.
If the request-URL identifies a version-controlled resource, the
resource just remains under version-control. This allows a client to
be unaware of whether or not a server automatically puts a resource
under version control when it is created.
If a VERSION-CONTROL request fails, the server state preceding the
request MUST be restored.
Marshalling:
If a request body is included, it MUST be a DAV:version-control
XML element.
<!ELEMENT version-control ANY>
If a response body for a successful request is included, it MUST
be a DAV:version-control-response XML element. Note that this
document does not define any elements for the VERSION-CONTROL
response body, but the DAV:version-control-response element is
defined to ensure interoperability between future extensions that
do define elements for the VERSION-CONTROL response body.
<!ELEMENT version-control-response ANY>
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Postconditions:
(DAV:put-under-version-control): If the request-URL identified a
versionable resource at the time of the request, the request MUST
have created a new version history and MUST have created a new
version resource in that version history. The resource MUST have
a DAV:checked-in property that identifies the new version. The
content, dead properties, and DAV:resourcetype of the new version
MUST be the same as those of the resource. Note that an
implementation can choose to locate the version history and
version resources anywhere that it wishes. In particular, it
could locate them on the same host and server as the version-
controlled resource, on a different virtual host maintained by the
same server, on the same host maintained by a different server, or
on a different host maintained by a different server.
(DAV:must-not-change-existing-checked-in-out): If the request-URL
identified a resource already under version control at the time of
the request, the request MUST NOT change the DAV:checked-in or
DAV:checked-out property of that version-controlled resource.
3.5.1 Example - VERSION-CONTROL
>>REQUEST
VERSION-CONTROL /foo.html HTTP/1.1
Host: www.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 200 OK
In this example, /foo.html is put under version control. A new
version history is created for it, and a new version is created that
has a copy of the content and dead properties of /foo.html. The
DAV:checked-in property of /foo.html identifies this new version.
3.6 REPORT Method
A REPORT request is an extensible mechanism for obtaining information
about a resource. Unlike a resource property, which has a single
value, the value of a report can depend on additional information
specified in the REPORT request body and in the REPORT request
headers.
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Marshalling:
The body of a REPORT request specifies which report is being
requested, as well as any additional information that will be used
to customize the report.
The request MAY include a Depth header. If no Depth header is
included, Depth:0 is assumed.
The response body for a successful request MUST contain the
requested report.
If a Depth request header is included, the response MUST be a 207
Multi-Status. The request MUST be applied separately to the
collection itself and to all members of the collection that
satisfy the Depth value. The DAV:prop element of a DAV:response
for a given resource MUST contain the requested report for that
resource.
Preconditions:
(DAV:supported-report): The specified report MUST be supported by
the resource identified by the request-URL.
Postconditions:
(DAV:no-modification): The REPORT method MUST NOT have changed the
content or dead properties of any resource.
3.7 DAV:version-tree Report
The DAV:version-tree report describes the requested properties of all
the versions in the version history of a version. If the report is
requested for a version-controlled resource, it is redirected to its
DAV:checked-in or DAV:checked-out version.
The DAV:version-tree report MUST be supported by all version
resources and all version-controlled resources.
Marshalling:
The request body MUST be a DAV:version-tree XML element.
<!ELEMENT version-tree ANY>
ANY value: a sequence of zero or more elements, with at most one
DAV:prop element.
prop: see RFC 2518, Section 12.11
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The response body for a successful request MUST be a
DAV:multistatus XML element.
multistatus: see RFC 2518, Section 12.9
The response body for a successful DAV:version-tree REPORT request
MUST contain a DAV:response element for each version in the
version history of the version identified by the request-URL.
3.7.1 Example - DAV:version-tree Report
The version history drawn below would produce the following version
tree report.
foo.html History
+---+
| | V1
+---+
/ \
/ \
+---+ +---+
| | V2 | | V2.1.1
+---+ +---+
>>REQUEST
REPORT /foo.html HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:version-tree xmlns:D="DAV:">
<D:prop>
<D:version-name/>
<D:creator-displayname/>
<D:successor-set/>
</D:prop>
</D:version-tree>
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>>RESPONSE
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>http://repo.webdav.org/his/23/ver/V1</D:href>
<D:propstat>
<D:prop>
<D:version-name>V1</D:version-name>
<D:creator-displayname>Fred</D:creator-displayname>
<D:successor-set>
<D:href>http://repo.webdav.org/his/23/ver/V2</D:href>
<D:href>http://repo.webdav.org/his/23/ver/V2.1.1</D:href>
</D:successor-set>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://repo.webdav.org/his/23/ver/V2</D:href>
<D:propstat>
<D:prop>
<D:version-name>V2</D:version-name>
<D:creator-displayname>Fred</D:creator-displayname>
<D:successor-set/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://repo.webdav.org/his/23/ver/V2.1.1</D:href>
<D:propstat>
<D:prop>
<D:version-name>V2.1.1</D:version-name>
<D:creator-displayname>Sally</D:creator-displayname>
<D:successor-set/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
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3.8 DAV:expand-property Report
Many property values are defined as a DAV:href, or a set of DAV:href
elements. The DAV:expand-property report provides a mechanism for
retrieving in one request the properties from the resources
identified by those DAV:href elements. This report not only
decreases the number of requests required, but also allows the server
to minimize the number of separate read transactions required on the
underlying versioning store.
The DAV:expand-property report SHOULD be supported by all resources
that support the REPORT method.
Marshalling:
The request body MUST be a DAV:expand-property XML element.
<!ELEMENT expand-property (property*)>
<!ELEMENT property (property*)>
<!ATTLIST property name NMTOKEN #REQUIRED>
name value: a property element type
<!ATTLIST property namespace NMTOKEN "DAV:">
namespace value: an XML namespace
The response body for a successful request MUST be a
DAV:multistatus XML element.
multistatus: see RFC 2518, Section 12.9
The properties reported in the DAV:prop elements of the
DAV:multistatus element MUST be those identified by the
DAV:property elements in the DAV:expand-property element. If
there are DAV:property elements nested within a DAV:property
element, then every DAV:href in the value of the corresponding
property is replaced by a DAV:response element whose DAV:prop
elements report the values of the properties identified by the
nested DAV:property elements. The nested DAV:property elements
can in turn contain DAV:property elements, so that multiple levels
of DAV:href expansion can be requested.
Note that a validating parser MUST be aware that the DAV:expand-
property report effectively modifies the DTD of every property by
replacing every occurrence of "href" in the DTD with "href |
response".
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3.8.1 Example - DAV:expand-property
This example describes how to query a version-controlled resource to
determine the DAV:creator-display-name and DAV:activity-set of every
version in the version history of that version-controlled resource.
This example assumes that the server supports the version-history
feature (see Section 5).
>>REQUEST
REPORT /foo.html HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:expand-property xmlns:D="DAV:">
<D:property name="version-history">
<D:property name="version-set">
<D:property name="creator-displayname"/>
<D:property name="activity-set"/>
</D:property>
</D:property>
</D:expand-property>
>>RESPONSE
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>http://www.webdav.org/foo.html</D:href>
<D:propstat>
<D:prop>
<D:version-history>
<D:response>
<D:href>http://repo.webdav.org/his/23</D:href>
<D:propstat>
<D:prop>
<D:version-set>
<D:response>
<D:href>http://repo.webdav.org/his/23/ver/1</D:href>
<D:propstat>
<D:prop>
<D:creator-displayname>Fred</D:creator-displayname>
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<D:activity-set> <D:href>
http://www.webdav.org/ws/dev/sally
</D:href> </D:activity-set> </D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat> </D:response>
<D:response>
<D:href>http://repo.webdav.org/his/23/ver/2</D:href>
<D:propstat>
<D:prop>
<D:creator-displayname>Sally</D:creator-displayname>
<D:activity-set>
<D:href>http://repo.webdav.org/act/add-refresh-cmd</D:href>
</D:activity-set> </D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat> </D:response>
</D:version-set> </D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat> </D:response>
</D:version-history> </D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat> </D:response>
</D:multistatus>
In this example, the DAV:creator-displayname and DAV:activity-set
properties of the versions in the DAV:version-set of the
DAV:version-history of http://www.webdav.org/foo.html are reported.
3.9 Additional OPTIONS Semantics
If the server supports the version-control feature, it MUST include
"version-control" as a field in the DAV response header from an
OPTIONS request on any resource that supports any versioning
properties, reports, or methods.
3.10 Additional PUT Semantics
Additional Preconditions:
(DAV:cannot-modify-version-controlled-content): If the request-URL
identifies a resource with a DAV:checked-in property, the request
MUST fail unless DAV:auto-version semantics will automatically
check out the resource.
(DAV:cannot-modify-version): If the request-URL identifies a
version, the request MUST fail.
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If the request creates a new resource that is automatically placed
under version control, all preconditions for VERSION-CONTROL apply
to the request.
Additional Postconditions:
(DAV:auto-checkout): If the resource was a checked-in version-
controlled resource whose DAV:auto-version property indicates it
should be automatically checked out but not automatically checked
in for a modification request, then the server MUST have
automatically checked out the resource prior to executing the
request. In particular, the value of the DAV:checked-out property
of the resource MUST be that of the DAV:checked-in property prior
to the request, the DAV:checked-in property MUST have been
removed, and the DAV:predecessor-set property MUST be initialized
to be the same as the DAV:checked-out property. If any part of
the checkout/update sequence failed, the status from the failed
part of the request MUST be returned, and the server state
preceding the request sequence MUST be restored.
(DAV:auto-checkout-checkin): If the resource was a checked-in
version-controlled resource whose DAV:auto-version property
indicates it should be automatically checked out and automatically
checked in for a modification request, then the server MUST have
automatically checked out the resource prior to executing the
request and automatically checked it in after the request. In
particular, the DAV:checked-in property of the resource MUST
identify a new version whose content and dead properties are the
same as those of the resource. The DAV:predecessor-set of the new
version MUST identify the version identified by the DAV:checked-in
property prior to the request. If any part of the
checkout/update/checkin sequence failed, the status from the
failed part of the request MUST be returned, and the server state
preceding the request sequence MUST be restored.
If the request creates a new resource, the new resource MAY have
automatically been placed under version control, and all
postconditions for VERSION-CONTROL apply to the request.
3.11 Additional PROPFIND Semantics
A DAV:allprop PROPFIND request SHOULD NOT return any of the
properties defined by this document. This allows a versioning server
to perform efficiently when a naive client, which does not understand
the cost of asking a server to compute all possible live properties,
issues a DAV:allprop PROPFIND request.
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Additional Preconditions:
(DAV:supported-live-property): If the request attempts to access a
property defined by this document, the semantics of that property
MUST be supported by the server.
3.12 Additional PROPPATCH Semantics
Additional Preconditions:
(DAV:cannot-modify-version-controlled-property): If the request
attempts to modify a dead property, same semantics as PUT (see
Section 3.10).
(DAV:cannot-modify-version): If the request attempts to modify a
dead property, same semantics as PUT (see Section 3.10).
(DAV:cannot-modify-protected-property): An attempt to modify a
property that is defined by this document, as being protected for
that kind of resource, MUST fail.
(DAV:supported-live-property): An attempt to modify a property
defined by this document, but whose semantics are not enforced by
the server, MUST fail. This helps ensure that a client will be
notified when it is trying to use a property whose semantics are
not supported by the server.
Additional Postconditions:
(DAV:auto-checkout): If the request modified a dead property, same
semantics as PUT (see Section 3.10).
(DAV:auto-checkout-checkin): If the request modified a dead
property, same semantics as PUT (see Section 3.10).
3.13 Additional DELETE Semantics
Additional Preconditions:
(DAV:no-version-delete): A server MAY fail an attempt to DELETE a
version.
Additional Postconditions:
(DAV:update-predecessor-set): If a version was deleted, the server
MUST have replaced any reference to that version in a
DAV:predecessor-set by a copy of the DAV:predecessor-set of the
deleted version.
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3.14 Additional COPY Semantics
Additional Preconditions:
If the request creates a new resource that is automatically placed
under version control, all preconditions for VERSION-CONTROL apply
to the request.
Additional Postconditions:
(DAV:must-not-copy-versioning-property): A property defined by
this document MUST NOT have been copied to the new resource
created by this request, but instead that property of the new
resource MUST have the default initial value it would have had if
the new resource had been created by a non-versioning method such
as PUT or a MKCOL.
(DAV:auto-checkout): If the destination is a version-controlled
resource, same semantics as PUT (see Section 3.10).
(DAV:auto-checkout-checkin): If the destination is a version-
controlled resource, same semantics as PUT (see Section 3.10).
(DAV:copy-creates-new-resource): If the source of a COPY is a
version-controlled resource or version, and if there is no
resource at the destination of the COPY, then the COPY creates a
new non-version-controlled resource at the destination of the
COPY. The new resource MAY automatically be put under version
control, but the resulting version-controlled resource MUST be
associated with a new version history created for that new
version-controlled resource, and all postconditions for
VERSION-CONTROL apply to the request.
3.15 Additional MOVE Semantics
Additional Preconditions:
(DAV:cannot-rename-version): If the request-URL identifies a
version, the request MUST fail.
Additional Postconditions:
(DAV:preserve-versioning-properties): When a resource is moved
from a source URL to a destination URL, a property defined by this
document MUST have the same value at the destination URL as it had
at the source URL.
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3.16 Additional UNLOCK Semantics
Note that these semantics apply both to an explicit UNLOCK request,
as well as to the removal of a lock because of a lock timeout. If a
precondition or postcondition cannot be satisfied, the lock timeout
MUST NOT occur.
Additional Preconditions:
(DAV:version-history-is-tree): If the request-URL identifies a
checked-out version-controlled resource that will be automatically
checked in when the lock is removed, then the versions identified
by the DAV:predecessor-set of the checked-out resource MUST be
descendants of the root version of the version history for the
DAV:checked-out version.
Additional Postconditions:
(DAV:auto-checkin): If the request-URL identified a checked-out
version-controlled resource that had been automatically checked
out because of its DAV:auto-version property, the request MUST
have created a new version in the version history of the
DAV:checked-out version. The request MUST have allocated a URL
for the version that MUST NOT have previously identified any other
resource, and MUST NOT ever identify a resource other than this
version. The content, dead properties, DAV:resourcetype, and
DAV:predecessor-set of the new version MUST be copied from the
checked-out resource. The DAV:version-name of the new version
MUST be set to a server-defined value distinct from all other
DAV:version-name values of other versions in the same version
history. The request MUST have removed the DAV:checked-out
property of the version-controlled resource, and MUST have added a
DAV:checked-in property that identifies the new version.
4 CHECKOUT-IN-PLACE FEATURE
With the version-control feature, WebDAV locking can be used to avoid
the proliferation of versions that would result if every modification
to a version-controlled resource produced a new version. The
checkout-in-place feature provides an alternative mechanism that
allows a client to explicitly check out and check in a resource to
create a new version.
4.1 Additional Version Properties
The checkout-in-place feature introduces the following REQUIRED
properties for a version.
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4.1.1 DAV:checkout-fork
This property controls the behavior of CHECKOUT when a version
already is checked out or has a successor. If the DAV:checkout-fork
of a version is DAV:forbidden, a CHECKOUT request MUST fail if it
would result in that version appearing in the DAV:predecessor-set or
DAV:checked-out property of more than one version or checked-out
resource. If DAV:checkout-fork is DAV:discouraged, such a CHECKOUT
request MUST fail unless DAV:fork-ok is specified in the CHECKOUT
request body.
A server MAY reject attempts to modify the DAV:checkout-fork of a
version.
<!ELEMENT checkout-fork ANY>
ANY value: A sequence of elements with at most one DAV:discouraged
or DAV:forbidden element.
<!ELEMENT discouraged EMPTY>
<!ELEMENT forbidden EMPTY>
4.1.2 DAV:checkin-fork
This property controls the behavior of CHECKIN when a version already
has a successor. If the DAV:checkin-fork of a version is
DAV:forbidden, a CHECKIN request MUST fail if it would result in that
version appearing in the DAV:predecessor-set of more than one
version. If DAV:checkin-fork is DAV:discouraged, such a CHECKIN
request MUST fail unless DAV:fork-ok is specified in the CHECKIN
request body.
A server MAY reject attempts to modify the DAV:checkout-fork of a
version.
<!ELEMENT checkin-fork ANY>
ANY value: A sequence of elements with at most one DAV:discouraged
or DAV:forbidden element.
<!ELEMENT discouraged EMPTY>
<!ELEMENT forbidden EMPTY>
4.2 Checked-Out Resource Properties
The checkout-in-place feature introduces the following REQUIRED
properties for a checked-out resource.
4.2.1 DAV:checkout-fork
This property determines the DAV:checkout-fork property of the
version that results from checking in this resource.
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4.2.2 DAV:checkin-fork
This property determines the DAV:checkin-fork property of the version
that results from checking in this resource.
4.3 CHECKOUT Method (applied to a version-controlled resource)
A CHECKOUT request can be applied to a checked-in version-controlled
resource to allow modifications to the content and dead properties of
that version-controlled resource.
If a CHECKOUT request fails, the server state preceding the request
MUST be restored.
Marshalling:
If a request body is included, it MUST be a DAV:checkout XML
element.
<!ELEMENT checkout ANY>
ANY value: A sequence of elements with at most one DAV:fork-ok
element.
<!ELEMENT fork-ok EMPTY>
If a response body for a successful request is included, it MUST
be a DAV:checkout-response XML element.
<!ELEMENT checkout-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:must-be-checked-in): If a version-controlled resource is
being checked out, it MUST have a DAV:checked-in property.
(DAV:checkout-of-version-with-descendant-is-forbidden): If the
DAV:checkout-fork property of the version being checked out is
DAV:forbidden, the request MUST fail if a version identifies that
version in its DAV:predecessor-set.
(DAV:checkout-of-version-with-descendant-is-discouraged): If the
DAV:checkout-fork property of the version being checked out is
DAV:discouraged, the request MUST fail if a version identifies
that version in its DAV:predecessor-set unless DAV:fork-ok is
specified in the request body.
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(DAV:checkout-of-checked-out-version-is-forbidden): If the
DAV:checkout-fork property of the version being checked out is
DAV:forbidden, the request MUST fail if a checked-out resource
identifies that version in its DAV:checked-out property.
(DAV:checkout-of-checked-out-version-is-discouraged): If the
DAV:checkout-fork property of the version being checked out is
DAV:discouraged, the request MUST fail if a checked-out resource
identifies that version in its DAV:checked-out property unless
DAV:fork-ok is specified in the request body.
Postconditions:
(DAV:is-checked-out): The checked-out resource MUST have a
DAV:checked-out property that identifies the DAV:checked-in
version preceding the checkout. The version-controlled resource
MUST NOT have a DAV:checked-in property.
(DAV:initialize-predecessor-set): The DAV:predecessor-set property
of the checked-out resource MUST be initialized to be the
DAV:checked-out version.
4.3.1 Example - CHECKOUT of a version-controlled resource
>>REQUEST
CHECKOUT /foo.html HTTP/1.1
Host: www.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 200 OK
Cache-Control: no-cache
In this example, the version-controlled resource /foo.html is checked
out.
4.4 CHECKIN Method (applied to a version-controlled resource)
A CHECKIN request can be applied to a checked-out version-controlled
resource to produce a new version whose content and dead properties
are copied from the checked-out resource.
If a CHECKIN request fails, the server state preceding the request
MUST be restored.
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Marshalling:
If a request body is included, it MUST be a DAV:checkin XML
element.
<!ELEMENT checkin ANY>
ANY value: A sequence of elements with at most one
DAV:keep-checked-out element and at most one DAV:fork-ok element.
<!ELEMENT keep-checked-out EMPTY>
<!ELEMENT fork-ok EMPTY>
If a response body for a successful request is included, it MUST
be a DAV:checkin-response XML element.
<!ELEMENT checkin-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:must-be-checked-out): The request-URL MUST identify a
resource with a DAV:checked-out property.
(DAV:version-history-is-tree) The versions identified by the
DAV:predecessor-set of the checked-out resource MUST be
descendants of the root version of the version history for the
DAV:checked-out version.
(DAV:checkin-fork-forbidden): A CHECKIN request MUST fail if it
would cause a version whose DAV:checkin-fork is DAV:forbidden to
appear in the DAV:predecessor-set of more than one version.
(DAV:checkin-fork-discouraged): A CHECKIN request MUST fail if it
would cause a version whose DAV:checkin-fork is DAV:discouraged to
appear in the DAV:predecessor-set of more than one version, unless
DAV:fork-ok is specified in the request body.
Postconditions:
(DAV:create-version): The request MUST have created a new version
in the version history of the DAV:checked-out version. The
request MUST have allocated a distinct new URL for the new
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version, and that URL MUST NOT ever identify any resource other
than that version. The URL for the new version MUST be returned in
a Location response header.
(DAV:initialize-version-content-and-properties): The content, dead
properties, DAV:resourcetype, and DAV:predecessor-set of the new
version MUST be copied from the checked-out resource. The
DAV:version-name of the new version MUST be set to a server-
defined value distinct from all other DAV:version-name values of
other versions in the same version history.
(DAV:checked-in): If the request-URL identifies a version-
controlled resource and DAV:keep-checked-out is not specified in
the request body, the DAV:checked-out property of the version-
controlled resource MUST have been removed and a DAV:checked-in
property that identifies the new version MUST have been added.
(DAV:keep-checked-out): If DAV:keep-checked-out is specified in
the request body, the DAV:checked-out property of the checked-out
resource MUST have been updated to identify the new version.
4.4.1 Example - CHECKIN
>>REQUEST
CHECKIN /foo.html HTTP/1.1
Host: www.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 201 Created
Location: http://repo.webdav.org/his/23/ver/32
Cache-Control: no-cache
In this example, version-controlled resource /foo.html is checked in,
and a new version is created at http://repo.webdav.org/his/23/ver/32.
4.5 UNCHECKOUT Method
An UNCHECKOUT request can be applied to a checked-out version-
controlled resource to cancel the CHECKOUT and restore the pre-
CHECKOUT state of the version-controlled resource.
If an UNCHECKOUT request fails, the server MUST undo any partial
effects of the UNCHECKOUT request.
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Marshalling:
If a request body is included, it MUST be a DAV:uncheckout XML
element.
<!ELEMENT uncheckout ANY>
If a response body for a successful request is included, it MUST
be a DAV:uncheckout-response XML element.
<!ELEMENT uncheckout-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:must-be-checked-out-version-controlled-resource): The
request-URL MUST identify a version-controlled resource with a
DAV:checked-out property.
Postconditions:
(DAV:cancel-checked-out): The value of the DAV:checked-in property
is that of the DAV:checked-out property prior to the request, and
the DAV:checked-out property has been removed.
(DAV:restore-content-and-dead-properties): The content and dead
properties of the version-controlled resource are copies of its
DAV:checked-in version.
4.5.1 Example - UNCHECKOUT
>>REQUEST
UNCHECKOUT /foo.html HTTP/1.1
Host: www.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 200 OK
Cache-Control: no-cache
In this example, the content and dead properties of the version-
controlled resource identified by http://www.webdav.org/foo.html are
restored to their values preceding the most recent CHECKOUT of that
version-controlled resource.
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4.6 Additional OPTIONS Semantics
If a server supports the checkout-in-place feature, it MUST include
"checkout-in-place" as a field in the DAV response header from an
OPTIONS request on any resource that supports any versioning
properties, reports, or methods.
5 Version-History Feature
It is often useful to have access to a version history even after all
version-controlled resources for that version history have been
deleted. A server can provide this functionality by supporting
version history resources. A version history resource is a resource
that exists in a server defined namespace and therefore is unaffected
by any deletion or movement of version-controlled resources. A
version history resource is an appropriate place to add a property
that logically applies to all states of a resource. The DAV:expand-
property report (see Section 3.8) can be applied to the DAV:version-
set of a version history resource to provide a variety of useful
reports on all versions in that version history.
5.1 Version History Properties
The DAV:resourcetype of a version history MUST be DAV:version-
history.
The version-history feature introduces the following REQUIRED
properties for a version history.
5.1.1 DAV:version-set (protected)
This property identifies each version of this version history.
<!ELEMENT version-set (href+)>
5.1.2 DAV:root-version (computed)
This property identifies the root version of this version history.
<!ELEMENT root-version (href)>
5.2 Additional Version-Controlled Resource Properties
The version-history feature introduces the following REQUIRED
property for a version-controlled resource.
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5.2.1 DAV:version-history (computed)
This property identifies the version history resource for the
DAV:checked-in or DAV:checked-out version of this version-controlled
resource.
<!ELEMENT version-history (href)>
5.3 Additional Version Properties
The version-history feature introduces the following REQUIRED
property for a version.
5.3.1 DAV:version-history (computed)
This property identifies the version history that contains this
version.
<!ELEMENT version-history (href)>
5.4 DAV:locate-by-history Report
Many properties identify a version from some version history. It is
often useful to be able to efficiently locate a version-controlled
resource for that version history. The DAV:locate-by-history report
can be applied to a collection to locate the collection member that
is a version-controlled resource for a specified version history
resource.
Marshalling:
The request body MUST be a DAV:locate-by-history XML element.
<!ELEMENT locate-by-history (version-history-set, prop)>
<!ELEMENT version-history-set (href+)>
prop: see RFC 2518, Section 12.11
The response body for a successful request MUST be a
DAV:multistatus XML element containing every version-controlled
resource that is a member of the collection identified by the
request-URL, and whose DAV:version-history property identifies one
of the version history resources identified by the request body.
The DAV:prop element in the request body identifies which
properties should be reported in the DAV:prop elements in the
response body.
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Preconditions:
(DAV:must-be-version-history): Each member of the DAV:version-
history-set element in the request body MUST identify a version
history resource.
5.4.1 Example - DAV:locate-by-history Report
>>REQUEST
REPORT /ws/public HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:locate-by-history xmlns:D="DAV:">
<D:version-history-set>
<D:href>http://repo.webdav.org/his/23</D:href>
<D:href>http://repo.webdav.org/his/84</D:href>
<D:href>http://repo.webdav.org/his/129</D:href>
<D:version-history-set/>
<D:prop>
</D:version-history>
</D:prop>
</D:locate-by-history>
>>RESPONSE
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>http://www.webdav.org/ws/public/x/test.html</D:href>
<D:propstat>
<D:prop>
<D:version-history>
<D:href>http://repo.webdav.org/his/23</D:href>
</D:version-history>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
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In this example, there is only one version-controlled member of
/ws/public that is a version-controlled resource for one of the three
specified version history resources. In particular,
/ws/public/x/test.html is the version-controlled resource for
http://repo.webdav.org/his/23.
5.5 Additional OPTIONS Semantics
If the server supports the version-history feature, it MUST include
"version-history" as a field in the DAV response header from an
OPTIONS request on any resource that supports any versioning
properties, reports, or methods.
A DAV:version-history-collection-set element MAY be included in the
request body to identify collections that may contain version history
resources.
Additional Marshalling:
If an XML request body is included, it MUST be a DAV:options XML
element.
<!ELEMENT options ANY>
ANY value: A sequence of elements with at most one
DAV:version-history-collection-set element.
If an XML response body for a successful request is included, it
MUST be a DAV:options-response XML element.
<!ELEMENT options-response ANY>
ANY value: A sequence of elements with at most one
DAV:version-history-collection-set element.
<!ELEMENT version-history-collection-set (href*)>
If DAV:version-history-collection-set is included in the request
body, the response body for a successful request MUST contain a
DAV:version-history-collection-set element identifying collections
that may contain version histories. An identified collection MAY
be the root collection of a tree of collections, all of which may
contain version histories. Since different servers can control
different parts of the URL namespace, different resources on the
same host MAY have different DAV:version-history-collection-set
values. The identified collections MAY be located on different
hosts from the resource.
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5.6 Additional DELETE Semantics
Additional Postconditions:
(DAV:delete-version-set): If the request deleted a version
history, the request MUST have deleted all versions in the
DAV:version-set of that version history, and MUST have satisfied
the postconditions for version deletion (see Section 3.13).
(DAV:version-history-has-root): If the request deleted the root
version of a version history, the request MUST have updated the
DAV:root-version of the version history to refer to another
version that is an ancestor of all other remaining versions in
that version history. A result of this postcondition is that
every version history will have at least one version, and the only
way to delete all versions is to delete the version history
resource.
5.7 Additional COPY Semantics
Additional Preconditions:
(DAV:cannot-copy-history): If the request-URL identifies a version
history, the request MUST fail. In order to create another
version history whose versions have the same content and dead
properties, the appropriate sequence of VERSION-CONTROL, CHECKOUT,
PUT, PROPPATCH, and CHECKIN requests must be made.
5.8 Additional MOVE Semantics
Additional Preconditions:
(DAV:cannot-rename-history): If the request-URL identifies a
version history, the request MUST fail.
5.9 Additional VERSION-CONTROL Semantics
Additional Postconditions:
(DAV:new-version-history): If the request created a new version
history, the request MUST have allocated a new server-defined URL
for that version history that MUST NOT have previously identified
any other resource, and MUST NOT ever identify a resource other
than this version history.
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5.10 Additional CHECKIN Semantics
Additional Postconditions:
(DAV:add-to-history): A URL for the new version resource MUST have
been added to the DAV:version-set of the version history of the
DAV:checked-out version.
6 Workspace Feature
In order to allow multiple users to work concurrently on adding
versions to the same version history, it is necessary to allocate on
the server multiple checked-out resources for the same version
history. Even if only one user is making changes to a resource, that
user will sometimes wish to create a "private" version, and then to
expose that version at a later time. One way to provide this
functionality depends on the client keeping track of its current set
of checked-out resources. This is the working-resource feature
defined in Section 8. The other way to provide this functionality
avoids the need for persistent state on the client, and instead has
the server maintain a human meaningful namespace for related sets of
checked-out resources. This is the workspace feature defined in this
section.
The workspace feature introduces a "workspace resource". A workspace
resource is a collection whose members are related version-controlled
and non-version-controlled resources. Multiple workspaces may be
used to expose different versions and configurations of a set of
version-controlled resources concurrently. In order to make changes
to a version-controlled resource in one workspace visible in another
workspace, that version-controlled resource must be checked in, and
then the corresponding version-controlled resource in the other
workspace can be updated to display the content and dead properties
of the new version.
In order to ensure unambiguous merging (see Section 11) and
baselining (see Section 12) semantics, a workspace may contain at
most one version-controlled resource for a given version history.
This is required for unambiguous merging because the MERGE method
must identify which version-controlled resource is to be the merge
target of a given version. This is required for unambiguous
baselining because a baseline can only select one version for a given
version-controlled resource.
Initially, an empty workspace can be created. Non-version-controlled
resources can then be added to the workspace with standard WebDAV
requests such as PUT and MKCOL. Version-controlled resources can be
added to the workspace with VERSION-CONTROL requests. If the
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RFC 3253 Versioning Extensions to WebDAV March 2002
baseline feature is supported, collections in the workspace can be
placed under baseline control, and then initialized by existing
baselines.
6.1 Workspace Properties
The workspace feature introduces the following REQUIRED property for
a workspace.
6.1.1 DAV:workspace-checkout-set (computed)
This property identifies each checked-out resource whose
DAV:workspace property identifies this workspace.
<!ELEMENT workspace-checkout-set (href*)>
6.2 Additional Resource Properties
The workspace feature introduces the following REQUIRED property for
a WebDAV resource.
6.2.1 DAV:workspace (protected)
The DAV:workspace property of a workspace resource MUST identify
itself. The DAV:workspace property of any other type of resource
MUST be the same as the DAV:workspace of its parent collection.
<!ELEMENT workspace (href)>
6.3 MKWORKSPACE Method
A MKWORKSPACE request creates a new workspace resource. A server MAY
restrict workspace creation to particular collections, but a client
can determine the location of these collections from a
DAV:workspace-collection-set OPTIONS request (see Section 6.4).
If a MKWORKSPACE request fails, the server state preceding the
request MUST be restored.
Marshalling:
If a request body is included, it MUST be a DAV:mkworkspace XML
element.
<!ELEMENT mkworkspace ANY>
If a response body for a successful request is included, it MUST
be a DAV:mkworkspace-response XML element.
Clemm, et al. Standards Track PAGE 48
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<!ELEMENT mkworkspace-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:resource-must-be-null): A resource MUST NOT exist at the
request-URL.
(DAV:workspace-location-ok): The request-URL MUST identify a
location where a workspace can be created.
Postconditions:
(DAV:initialize-workspace): A new workspace exists at the
request-URL. The DAV:resourcetype of the workspace MUST be
DAV:collection. The DAV:workspace of the workspace MUST identify
the workspace.
6.3.1 Example - MKWORKSPACE
>>REQUEST
MKWORKSPACE /ws/public HTTP/1.1
Host: www.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 201 Created
Cache-Control: no-cache
In this example, a new workspace is created at
http://www.webdav.org/ws/public.
6.4 Additional OPTIONS Semantics
If a server supports the workspace feature, it MUST include
"workspace" as a field in the DAV response header from an OPTIONS
request on any resource that supports any versioning properties,
reports, or methods.
If a server supports the workspace feature, it MUST also support the
checkout-in-place feature and the version-history feature.
A DAV:workspace-collection-set element MAY be included in the request
body to identify collections that may contain workspace resources.
Clemm, et al. Standards Track PAGE 49
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Additional Marshalling:
If an XML request body is included, it MUST be a DAV:options XML
element.
<!ELEMENT options ANY>
ANY value: A sequence of elements with at most one
DAV:workspace-collection-set element.
If an XML response body for a successful request is included, it
MUST be a DAV:options-response XML element.
<!ELEMENT options-response ANY>
ANY value: A sequence of elements with at most one
DAV:workspace-collection-set element.
<!ELEMENT workspace-collection-set (href*)>
If DAV:workspace-collection-set is included in the request body,
the response body for a successful request MUST contain a
DAV:workspace-collection-set element identifying collections that
may contain workspaces. An identified collection MAY be the root
collection of a tree of collections, all of which may contain
workspaces. Since different servers can control different parts
of the URL namespace, different resources on the same host MAY
have different DAV:workspace-collection-set values. The
identified collections MAY be located on different hosts from the
resource.
Clemm, et al. Standards Track PAGE 50
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6.4.1 Example - OPTIONS
>>REQUEST
OPTIONS /doc HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:options xmlns:D="DAV:">
<D:version-history-collection-set/>
<D:workspace-collection-set/>
</D:options>
>>RESPONSE
HTTP/1.1 200 OK
DAV: 1
DAV: version-control,checkout-in-place,version-history,workspace
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:options-response xmlns:D="DAV:">
<D:version-history-collection-set>
<D:href>http://repo.webdav.org/his</D:href>
</D:version-history-collection-set>
<D:workspace-collection-set>
<D:href>http://www.webdav.org/public/ws</D:href>
<D:href>http://www.webdav.org/private/ws</D:href>
</D:workspace-collection-set>
</D:options-response>
In this example, the server indicates that it provides Class 1 DAV
support and basic-server-workspace versioning support. In addition,
the server indicates the requested locations of the version history
resources and the workspace resources.
6.5 Additional DELETE Semantics
Additional Postconditions:
(DAV:delete-workspace-members): If a workspace is deleted, any
resource that identifies that workspace in its DAV:workspace
property MUST be deleted.
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6.6 Additional MOVE Semantics
Additional Postconditions:
(DAV:workspace-member-moved): If the request-URL did not identify
a workspace, the DAV:workspace of the destination MUST have been
updated to have the same value as the DAV:workspace of the parent
collection of the destination.
(DAV:workspace-moved): If the request-URL identified a workspace,
any reference to that workspace in a DAV:workspace property MUST
have been updated to refer to the new location of that workspace.
6.7 Additional VERSION-CONTROL Semantics
A VERSION-CONTROL request can be used to create a new version-
controlled resource for an existing version history. This allows the
creation of version-controlled resources for the same version history
in multiple workspaces.
Additional Marshalling:
<!ELEMENT version-control ANY>
ANY value: A sequence of elements with at most one DAV:version
element.
<!ELEMENT version (href)>
Additional Preconditions:
(DAV:cannot-add-to-existing-history): If the DAV:version-control
request body element contains a DAV:version element, the request-
URL MUST NOT identify a resource.
(DAV:must-be-version): The DAV:href of the DAV:version element
MUST identify a version.
(DAV:one-version-controlled-resource-per-history-per-workspace):
If the DAV:version-control request body specifies a version, and
if the request-URL is a member of a workspace, then there MUST NOT
already be a version-controlled member of that workspace whose
DAV:checked-in or DAV:checked-out property identifies any version
from the version history of the version specified in the request
body.
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Additional Postconditions:
(DAV:new-version-controlled-resource): If the request-URL did NOT
identify a resource, a new version-controlled resource exists at
the request-URL whose content and dead properties are initialized
by those of the version in the request body, and whose
DAV:checked-in property identifies that version.
6.7.1 Example - VERSION-CONTROL (using an existing version history)
>>REQUEST
VERSION-CONTROL /ws/public/bar.html HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:version-control xmlns:D="DAV:">
<D:version>
<D:href>http://repo.webdav.org/his/12/ver/V3</D:href>
</D:version>
</D:version-control>
>>RESPONSE
HTTP/1.1 201 Created
Cache-Control: no-cache
In this example, a new version-controlled resource is created at
/ws/public/bar.html. The content and dead properties of the new
version-controlled resource are initialized to be the same as those
of the version identified by http://repo.webdav.org/his/12/ver/V3.
7 UPDATE Feature
The update feature provides a mechanism for changing the state of a
checked-in version-controlled resource to be that of another version
from the version history of that resource.
7.1 UPDATE Method
The UPDATE method modifies the content and dead properties of a
checked-in version-controlled resource (the "update target") to be
those of a specified version (the "update source") from the version
history of that version-controlled resource.
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The response to an UPDATE request identifies the resources modified
by the request, so that a client can efficiently update any cached
state it is maintaining. Extensions to the UPDATE method allow
multiple resources to be modified from a single UPDATE request (see
Section 12.13).
Marshalling:
The request body MUST be a DAV:update element.
<!ELEMENT update ANY>
ANY value: A sequence of elements with at most one DAV:version
element and at most one DAV:prop element.
<!ELEMENT version (href)>
prop: see RFC 2518, Section 12.11
The response for a successful request MUST be a 207 Multi-Status,
where the DAV:multistatus XML element in the response body
identifies all resources that have been modified by the request.
multistatus: see RFC 2518, Section 12.9
The response MUST include a Cache-Control:no-cache header.
Postconditions:
(DAV:update-content-and-properties): If the DAV:version element in
the request body identified a version that is in the same version
history as the DAV:checked-in version of a version-controlled
resource identified by the request-URL, then the content and dead
properties of that version-controlled resource MUST be the same as
those of the version specified by the DAV:version element, and the
DAV:checked-in property of the version-controlled resource MUST
identify that version. The request-URL MUST appear in a
DAV:response element in the response body.
(DAV:report-properties): If DAV:prop is specified in the request
body, the properties specified in the DAV:prop element MUST be
reported in the DAV:response elements in the response body.
Clemm, et al. Standards Track PAGE 54
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7.1.1 Example - UPDATE
>>REQUEST
UPDATE /foo.html HTTP/1.1
Host: www.webdav.org
Content-type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:update xmlns:D="DAV:">
<D:version>
<D:href>http://repo.webdav.org/his/23/ver/33</D:href>
</D:version>
</D:update>
>>RESPONSE
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Cache-Control: no-cache
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>http://www.webdav.org/foo.html</D:href>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
In this example, the content and dead properties of
http://repo.webdav.org/his/23/ver/33 are copied to the version-
controlled resource /foo.html, and the DAV:checked-in property of
/foo.html is updated to refer to
http://repo.webdav.org/his/23/ver/33.
7.2 Additional OPTIONS Semantics
If the server supports the update feature, it MUST include "update"
as a field in the DAV response header from an OPTIONS request on any
resource that supports any versioning properties, reports, or
methods.
Clemm, et al. Standards Track PAGE 55
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8 Label Feature
A version "label" is a string that distinguishes one version in a
version history from all other versions in that version history. A
label can automatically be assigned by a server, or it can be
assigned by a client in order to provide a meaningful name for that
version. A given version label can be assigned to at most one
version of a given version history, but client assigned labels can be
reassigned to another version at any time. Note that although a
given label can be applied to at most one version from the same
version history, the same label can be applied to versions from
different version histories.
For certain methods, if the request-URL identifies a version-
controlled resource, a label can be specified in a Label request
header (see Section 8.3) to cause the method to be applied to the
version selected by that label from the version history of that
version-controlled resource.
8.1 Additional Version Properties
The label feature introduces the following REQUIRED property for a
version.
8.1.1 DAV:label-name-set (protected)
This property contains the labels that currently select this version.
<!ELEMENT label-name-set (label-name*)>
<!ELEMENT label-name (#PCDATA)>
PCDATA value: string
8.2 LABEL Method
A LABEL request can be applied to a version to modify the labels that
select that version. The case of a label name MUST be preserved when
it is stored and retrieved. When comparing two label names to decide
if they match or not, a server SHOULD use a case-sensitive URL-
escaped UTF-8 encoded comparison of the two label names.
If a LABEL request is applied to a checked in version-controlled
resource, the operation MUST be applied to the DAV:checked-in version
of that version-controlled resource.
Clemm, et al. Standards Track PAGE 56
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Marshalling:
The request body MUST be a DAV:label element.
<!ELEMENT label ANY>
ANY value: A sequence of elements with at most one DAV:add,
DAV:set, or DAV:remove element.
<!ELEMENT add (label-name)>
<!ELEMENT set (label-name)>
<!ELEMENT remove (label-name)>
<!ELEMENT label-name (#PCDATA)>
PCDATA value: string
The request MAY include a Label header.
The request MAY include a Depth header. If no Depth header is
included, Depth:0 is assumed. Standard depth semantics apply, and
the request is applied to the collection identified by the
request-URL and to all members of the collection that satisfy the
Depth value. If a Depth header is included and the request fails
on any resource, the response MUST be a 207 Multi-Status that
identifies all resources for which the request has failed.
If a response body for a successful request is included, it MUST
be a DAV:label-response XML element.
<!ELEMENT label-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:must-be-checked-in): If the request-URL identifies a
version-controlled resource, the version-controlled resource MUST
be checked in.
(DAV:must-select-version-in-history): If a Label request header is
included and the request-URL identifies a version-controlled
resource, the specified label MUST select a version in the version
history of the version-controlled resource.
(DAV:add-must-be-new-label): If DAV:add is specified in the
request body, the specified label MUST NOT appear in the
DAV:label-name-set of any version in the version history of that
version-controlled resource.
Clemm, et al. Standards Track PAGE 57
RFC 3253 Versioning Extensions to WebDAV March 2002
(DAV:label-must-exist): If DAV:remove is specified in the request
body, the specified label MUST appear in the DAV:label-name-set of
that version.
Postconditions:
(DAV:add-or-set-label): If DAV:add or DAV:set is specified in the
request body, the specified label MUST appear in the DAV:label-
name-set of the specified version, and MUST NOT appear in the
DAV:label-name-set of any other version in the version history of
that version.
(DAV:remove-label): If DAV:remove is specified in the request
body, the specified label MUST NOT appear in the DAV:label-name-
set of any version in the version history of that version.
8.2.1 Example - Setting a label
>>REQUEST
LABEL /foo.html HTTP/1.1
Host: www.webdav.org
Content-type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:label xmlns:D="DAV:">
<D:set>
<D:label-name>default</D:label-name>
</D:set>
</D:label>
>>RESPONSE
HTTP/1.1 200 OK
Cache-Control: no-cache
In this example, the label "default" is applied to the DAV:checked-in
version of /foo.html.
8.3 Label Header
For certain methods (e.g. GET, PROPFIND), if the request-URL
identifies a version-controlled resource, a label can be specified in
a Label request header to cause the method to be applied to the
version selected by that label from the version history of that
version-controlled resource.
Clemm, et al. Standards Track PAGE 58
RFC 3253 Versioning Extensions to WebDAV March 2002
The value of a label header is the name of a label, encoded using
URL-escaped UTF-8. For example, the label "release B.3" is
identified by the following header:
Label: release%20B.3
A Label header MUST have no effect on a request whose request-URL
does not identify a version-controlled resource. In particular, it
MUST have no effect on a request whose request-URL identifies a
version or a version history.
A server MUST return an HTTP-1.1 Vary header containing Label in a
successful response to a cacheable request (e.g., GET) that includes
a Label header.
8.4 Additional OPTIONS Semantics
If the server supports the label feature, it MUST include "label" as
a field in the DAV response header from an OPTIONS request on any
resource that supports any versioning properties, reports, or
methods.
8.5 Additional GET Semantics
Additional Marshalling:
The request MAY include a Label header.
Additional Preconditions:
(DAV:must-select-version-in-history): If a Label request header is
included and the request-URL identifies a version-controlled
resource, the specified label MUST select a version in the version
history of the version-controlled resource.
Additional Postconditions:
(DAV:apply-request-to-labeled-version): If the request-URL
identifies a version-controlled resource and a Label request
header is included, the response MUST contain the content of the
specified version rather than that of the version-controlled
resource.
8.6 Additional PROPFIND Semantics
Additional Marshalling:
The request MAY include a Label header.
Clemm, et al. Standards Track PAGE 59
RFC 3253 Versioning Extensions to WebDAV March 2002
Additional Preconditions:
(DAV:must-select-version-in-history): If a Label request header is
included and the request-URL identifies a version-controlled
resource, the specified label MUST select a version in the version
history of the version-controlled resource.
Additional Postconditions:
(DAV:apply-request-to-labeled-version): If the request-URL
identifies a version-controlled resource and a Label request
header is included, the response MUST contain the properties of
the specified version rather than that of the version-controlled
resource.
8.7 Additional COPY Semantics
Additional Marshalling:
The request MAY include a Label header.
Additional Preconditions:
(DAV:must-select-version-in-history): If a Label request header is
included and the request-URL identifies a version-controlled
resource, the specified label MUST select a version in the version
history of the version-controlled resource.
Additional Postconditions:
(DAV:apply-request-to-labeled-version): If the request-URL
identifies a version-controlled resource and a Label request
header is included, the request MUST have copied the properties
and content of the specified version rather than that of the
version-controlled resource.
8.8 Additional CHECKOUT Semantics
If the server supports the working-resource option, a LABEL header
may be included to check out the version selected by the specified
label.
Additional Marshalling:
The request MAY include a Label header.
Clemm, et al. Standards Track PAGE 60
RFC 3253 Versioning Extensions to WebDAV March 2002
Additional Preconditions:
(DAV:must-select-version-in-history): If a Label request header is
included and the request-URL identifies a version-controlled
resource, the specified label MUST select a version in the version
history of the version-controlled resource.
(DAV:must-not-have-label-and-apply-to-version): If a Label request
header is included, the request body MUST NOT contain a
DAV:apply-to-version element.
Additional Postconditions:
(DAV:apply-request-to-labeled-version): If the request-URL
identifies a checked-in version-controlled resource, and a Label
request header is included, the CHECKOUT MUST have been applied to
the version selected by the specified label, and not to the
version-controlled resource itself.
8.9 Additional UPDATE Semantics
If the request body of an UPDATE request contains a DAV:label-name
element, the update target is the resource identified by the
request-URL, and the update source is the version selected by the
specified label from the version history of the update target.
Additional Marshalling:
<!ELEMENT update ANY>
ANY value: A sequence of elements with at most one DAV:label-name
or DAV:version element (but not both).
<!ELEMENT label-name (#PCDATA)>
PCDATA value: string
The request MAY include a Depth header. If no Depth header is
included, Depth:0 is assumed. Standard depth semantics apply, and
the request is applied to the collection identified by the
request-URL and to all members of the collection that satisfy the
Depth value. If a Depth header is included and the request fails
on any resource, the response MUST be a 207 Multi-Status that
identifies all resources for which the request has failed.
Additional Preconditions:
(DAV:must-select-version-in-history): If the request includes a
DAV:label-name element in the request body, the label MUST select
a version in the version history of the version-controlled
resource identified by the request-URL.
Clemm, et al. Standards Track PAGE 61
RFC 3253 Versioning Extensions to WebDAV March 2002
(DAV:depth-update): If the request includes a Depth header,
standard depth semantics apply, and the request is applied to the
collection identified by the request-URL and to all members of the
collection that satisfy the Depth value. The request MUST be
applied to a collection before being applied to any members of
that collection, since an update of a version-controlled
collection might change the membership of that collection.
Additional Postconditions:
(DAV:apply-request-to-labeled-version): If a DAV:label-name
element appears in the request body, the content and dead
properties of the version-controlled resource must have been
updated to be those of the version selected by that label.
9 Working-Resource Feature
The working-resource feature provides an alternative to the workspace
feature for supporting parallel development. Unlike the workspace
feature, where the desired configuration of versions and checked-out
resources is maintained on the server, the working-resource feature
maintains the configuration on the client. This simplifies the
server implementation, but does not allow a user to access the
configuration from clients in different physical locations, such as
from another office, from home, or while traveling. Another
difference is that the workspace feature isolates clients from a
logical change that involves renaming shared resources, until that
logical change is complete and tested; with the working resource
feature, all clients use a common set of shared version-controlled
resources and every client sees the result of a MOVE as soon as it
occurs.
If a server supports the working-resource feature but not the
checkout-in-place feature, a CHECKOUT request can only be used to
create a working resource, and cannot be used to check out a
version-controlled resource. If a server supports the checkout-in-
place feature, but not the working-resource feature, a CHECKOUT can
only be used to change the state of a version-controlled resource
from checked-in to checked-out.
9.1 Additional Version Properties
The working-resource feature introduces the following REQUIRED
properties for a version.
9.1.1 DAV:checkout-fork
This property is defined in Section 4.1.1.
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9.1.2 DAV:checkin-fork
This property is defined in Section 4.1.2.
9.2 Working Resource Properties
The working-resource feature introduces the following REQUIRED
properties for a working resource. Since a working resource is a
checked-out resource, it also has any property defined in this
document for a checked-out resource.
9.2.1 DAV:auto-update (protected)
This property identifies the version-controlled resource that will be
updated when the working resource is checked in.
<!ELEMENT auto-update (href)>
9.2.2 DAV:checkout-fork
This property is defined in Section 4.2.1.
9.2.3 DAV:checkin-fork
This property is defined in Section 4.2.2.
9.3 CHECKOUT Method (applied to a version)
A CHECKOUT request can be applied to a version to create a new
working resource. The content and dead properties of the working
resource are a copy of the version that was checked out.
Marshalling:
If a request body is included, it MUST be a DAV:checkout XML
element.
<!ELEMENT checkout ANY>
ANY value: A sequence of elements with at most one DAV:apply-to-
version and at most one DAV:fork-ok element.
<!ELEMENT apply-to-version EMPTY>
<!ELEMENT fork-ok EMPTY>
If a response body for a successful request is included,
it MUST be a DAV:checkout-response XML element.
Clemm, et al. Standards Track PAGE 63
RFC 3253 Versioning Extensions to WebDAV March 2002
<!ELEMENT checkout-response ANY>
The response MUST include a Location header.
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:checkout-of-version-with-descendant-is-forbidden): See
Section 4.3.
(DAV:checkout-of-version-with-descendant-is-discouraged): See
Section 4.3.
(DAV:checkout-of-checked-out-version-is-forbidden): See Section
4.3.
(DAV:checkout-of-checked-out-version-is-discouraged): See Section
4.3.
Postconditions:
(DAV:create-working-resource): If the request-URL identified a
version, the Location response header MUST contain the URL of a
new working resource. The DAV:checked-out property of the new
working resource MUST identify the version that was checked out.
The content and dead properties of the working resource MUST be
copies of the content and dead properties of the DAV:checked-out
version. The DAV:predecessor-set property of the working resource
MUST be initialized to be the version identified by the request-
URL. The DAV:auto-update property of the working resource MUST
NOT exist.
(DAV:create-working-resource-from-checked-in-version): If the
request-URL identified a version-controlled resource, and
DAV:apply-to-version is specified in the request body, the
CHECKOUT is applied to the DAV:checked-in version of the version-
controlled resource, and not the version-controlled resource
itself. A new working resource is created and the version-
controlled resource remains checked-in. The DAV:auto-update
property of the working resource MUST identify the version-
controlled resource.
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9.3.1 Example - CHECKOUT of a version
>>REQUEST
CHECKOUT /his/12/ver/V3 HTTP/1.1
Host: repo.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 201 Created
Location: http://repo.webdav.org/wr/157
Cache-Control: no-cache
In this example, the version identified by
http://repo.webdav.org/his/12/ver/V3 is checked out, and the new
working resource is located at http://repo.webdav.org/wr/157.
9.4 CHECKIN Method (applied to a working resource)
A CHECKIN request can be applied to a working resource to produce a
new version whose content and dead properties are a copy of those of
the working resource. If the DAV:auto-update property of the working
resource was set because the working resource was created by applying
a CHECKOUT with the DAV:apply-to-version flag to a version-controlled
resource, the CHECKIN request will also update the content and dead
properties of that version-controlled resource to be those of the new
version.
Marshalling:
If a request body is included, it MUST be a DAV:checkin XML
element.
<!ELEMENT checkin ANY>
ANY value: A sequence of elements with at most one DAV:fork-ok
element.
<!ELEMENT fork-ok EMPTY>
If a response body for a successful request is included, it MUST
be a DAV:checkin-response XML element.
<!ELEMENT checkin-response ANY>
The response MUST include a Cache-Control:no-cache header.
Clemm, et al. Standards Track PAGE 65
RFC 3253 Versioning Extensions to WebDAV March 2002
Preconditions:
(DAV:must-be-checked-out): See Section 4.4.
(DAV:version-history-is-tree) See Section 4.4.
(DAV:checkin-fork-forbidden): See Section 4.4.
(DAV:checkin-fork-discouraged): See Section 4.4.
(DAV:no-overwrite-by-auto-update): If the DAV:auto-update property
for the checked-out resource identifies a version-controlled
resource, at least one of the versions identified by the
DAV:predecessor-set property of the checked-out resource MUST
identify a version that is either the same as or a descendant of
the version identified by the DAV:checked-in property of that
version-controlled resource.
Postconditions:
(DAV:create-version): See Section 4.4.
(DAV:initialize-version-content-and-properties): See Section 4.4.
(DAV:auto-update): If the DAV:auto-update property of the
checked-out resource identified a version-controlled resource, an
UPDATE request with the new version MUST have been applied to that
version-controlled resource.
(DAV:delete-working-resource): If the request-URL identifies a
working resource and if DAV:keep-checked-out is not specified in
the request body, the working resource is deleted.
9.4.1 Example - CHECKIN of a working resource
>>REQUEST
CHECKIN /wr/157 HTTP/1.1
Host: repo.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 201 Created
Location: http://repo.webdav.org/his/23/ver/15
Cache-Control: no-cache
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In this example, the working resource /wr/157 checked in, and a new
version is created at http://repo.webdav.org/his/23/ver/15.
9.5 Additional OPTIONS Semantics
If the server supports the working-resource feature, it MUST include
"working-resource" as a field in the DAV response header from an
OPTIONS request on any resource that supports any versioning
properties, reports, or methods.
9.6 Additional COPY Semantics
Additional Postconditions:
(DAV:copy-creates-new-resource): The result of copying a working
resource is a new non-version-controlled resource at the
destination of the COPY. The new resource MAY automatically be
put under version control, but the resulting version-controlled
resource MUST be associated with a new version history created for
that new version-controlled resource.
9.7 Additional MOVE Semantics
Additional Preconditions:
(DAV:cannot-rename-working-resource): If the request-URL
identifies a working resource, the request MUST fail.
Additional Postconditions:
(DAV:update-auto-update): If the request-URL identified a
version-controlled resource, any DAV:auto-update properties that
identified that version-controlled resource MUST have been updated
to contain the new location of that version-controlled resource.
10 Advanced Versioning Features
Advanced versioning addresses the problems of parallel development
and configuration management of multiple sets of interrelated
resources. Traditionally, artifacts of software development,
including requirements, design documents, code, and test cases, have
been a focus of configuration management. Web sites, comprising
multiple inter-linked resources (HTML, graphics, sound, CGI, and
others), are another class of complex information artifacts that
benefit from the application of configuration management. The
advanced versioning capabilities for coordinating concurrent change
provide the infrastructure for efficient and controlled management of
large evolving web sites.
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10.1 Advanced Versioning Packages
Although a server MAY support any combination of advanced versioning
features, in order to minimize the complexity of a WebDAV advanced
versioning client, a WebDAV advanced versioning server SHOULD support
one of the following packages:
Advanced-Server-Workspace Package: basic-server-workspace package
plus all advanced features
Advanced-Client-Workspace Package: basic-client-workspace package
plus all advanced features
The advanced-server-workspace package supports advanced versioning
capabilities for a client with no persistent state. The advanced-
client-workspace package supports advanced versioning capabilities
for a client that maintains configuration state on the client. A
server that supports both advanced workspace packages will
interoperate with all versioning clients.
10.2 Advanced Versioning Terms
The following additional terms are used by the advanced versioning
features.
Collection
A "collection" is a resource whose state consists of not only
content and properties, but also a set of named "bindings", where
a binding identifies what RFC 2518 calls an "internal member" of
the collection. Note that a binding is not a resource, but rather
is a part of the state of a collection that defines a mapping from
a binding name (a URL segment) to a resource (an internal member
of the collection).
Collection Version Resource
A "collection version resource", or simply "collection version",
captures the dead properties of a version-controlled collection,
as well as the names of its version-controlled bindings (see
Section 14). A version-controlled binding is a binding to a
version-controlled resource. If the checkout-in-place feature is
supported, a collection version can be created by checking out and
then checking in a version-controlled collection. If the
working-resource feature is supported, a collection version can be
created by checking out a collection version (to create a "working
collection") and then checking in the working collection.
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Configuration
A "configuration" is a set of resources that consists of a root
collection and all members (not just internal members) of that
root collection that are not members of another configuration.
The root collection is called the "configuration root", and the
members of this set are called the "members of the configuration".
Note that a collection (which is a single resource) is very
different from a configuration (which is a set of resources).
Baseline Resource
A "baseline resource", or simply "baseline", of a collection is a
version of the configuration that is rooted at that collection
(see Section 12). In particular, a baseline captures the
DAV:checked-in version of every version-controlled member of that
configuration. Note that a collection version (which captures the
state of a single resource) is very different from a collection
baseline (which captures the state of a set of resources).
Baseline-Controlled Collection
A "baseline-controlled collection" is a collection from which
baselines can be created (see Section 12).
Version-Controlled Configuration Resource
A "version-controlled configuration resource", or simply
"version-controlled configuration", is a special kind of version-
controlled resource that is associated with a baseline-controlled
collection, and is used to create and access baselines of that
collection (see Section 12). When a collection is both version-
controlled and baseline-controlled, a client can create a new
version of the collection by checking out and checking in that
collection, and it can create a new baseline of that collection by
checking out and checking in the version-controlled configuration
of that collection.
Activity Resource
An "activity resource", or simply "activity", is a resource that
selects a set of versions that correspond to a single logical
change, where the versions selected from a given version history
form a single line of descent through that version history (see
Section 13).
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11 Merge Feature
When a user wants to accept the changes (new versions) created by
someone else, it is important not just to update the version-
controlled resources in the user's workspace with those new versions,
since this could result in "backing out" changes the user has made to
those version-controlled resources. Instead, the versions created in
another workspace should be "merged" into the user's version-
controlled resources.
The version history of a version-controlled resource provides the
information needed to determine the result of the merge. In
particular, the merge should select whichever version is later in the
line of descent from the root version. In case the versions to be
merged are on different lines of descent (neither version is a
descendant of the other), neither version should be selected, but
instead, a new version should be created that contains the logical
merge of the content and dead properties of those versions. The
MERGE request can be used to check out each version-controlled
resource that requires such a merge, and set the DAV:merge-set
property of each checked-out resource to identify the version to be
merged. The user is responsible for modifying the content and dead
properties of the checked-out resource so that it represents the
logical merge of that version, and then adding that version to the
DAV:predecessor-set of the checked-out resource.
If the server is capable of automatically performing the merge, it
MAY update the content, dead properties, and DAV:predecessor-set of
the checked-out resource itself. Before checking in the
automatically merged resource, the user is responsible for verifying
that the automatic merge is correct.
11.1 Additional Checked-Out Resource Properties
The merge feature introduces the following REQUIRED properties for a
checked-out resource.
11.1.1 DAV:merge-set
This property identifies each version that is to be merged into this
checked-out resource.
<!ELEMENT merge-set (href*)>
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11.1.2 DAV:auto-merge-set
This property identifies each version that the server has merged into
this checked-out resource. The client should confirm that the merge
has been performed correctly before moving a URL from the DAV:auto-
merge-set to the DAV:predecessor-set of a checked-out resource.
<!ELEMENT auto-merge-set (href*)>
11.2 MERGE Method
The MERGE method performs the logical merge of a specified version
(the "merge source") into a specified version-controlled resource
(the "merge target"). If the merge source is neither an ancestor nor
a descendant of the DAV:checked-in or DAV:checked-out version of the
merge target, the MERGE checks out the merge target (if it is not
already checked out) and adds the URL of the merge source to the
DAV:merge-set of the merge target. It is then the client's
responsibility to update the content and dead properties of the
checked-out merge target so that it reflects the logical merge of the
merge source into the current state of the merge target. The client
indicates that it has completed the update of the merge target, by
deleting the merge source URL from the DAV:merge-set of the checked-
out merge target, and adding it to the DAV:predecessor-set. As an
error check for a client forgetting to complete a merge, the server
MUST fail an attempt to CHECKIN a version-controlled resource with a
non-empty DAV:merge-set.
When a server has the ability to automatically update the content and
dead properties of the merge target to reflect the logical merge of
the merge source, it may do so unless DAV:no-auto-merge is specified
in the MERGE request body. In order to notify the client that a
merge source has been automatically merged, the MERGE request MUST
add the URL of the auto-merged source to the DAV:auto-merge-set
property of the merge target, and not to the DAV:merge-set property.
The client indicates that it has verified that the auto-merge is
valid, by deleting the merge source URL from the DAV:auto-merge-set,
and adding it to the DAV:predecessor-set.
Multiple merge sources can be specified in a single MERGE request.
The set of merge sources for a MERGE request is determined from the
DAV:source element of the MERGE request body as follows:
- If DAV:source identifies a version, that version is a merge
source.
- If DAV:source identifies a version-controlled resource, the
DAV:checked-in version of that version-controlled resource is a
merge source.
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- If DAV:source identifies a collection, the DAV:checked-in version
of each version-controlled resource that is a member of that
collection is a merge source.
The request-URL identifies the set of possible merge targets. If the
request-URL identifies a collection, any member of the configuration
rooted at the request-URL is a possible merge target. The merge
target of a particular merge source is the version-controlled or
checked-out resource whose DAV:checked-in or DAV:checked-out version
is from the same version history as the merge source. If a merge
source has no merge target, that merge source is ignored.
The MERGE response identifies the resources that a client must modify
to complete the merge. It also identifies the resources modified by
the request, so that a client can efficiently update any cached state
it is maintaining.
Marshalling:
The request body MUST be a DAV:merge element.
The set of merge sources is determined by the DAV:source element
in the request body.
<!ELEMENT merge ANY>
ANY value: A sequence of elements with one DAV:source element, at
most one DAV:no-auto-merge element, at most one DAV:no-checkout
element, at most one DAV:prop element, and any legal set of
elements that can occur in a DAV:checkout element.
<!ELEMENT source (href+)>
<!ELEMENT no-auto-merge EMPTY>
<!ELEMENT no-checkout EMPTY>
prop: see RFC 2518, Section 12.11
The response for a successful request MUST be a 207 Multi-Status,
where the DAV:multistatus XML element in the response body
identifies all resources that have been modified by the request.
multistatus: see RFC 2518, Section 12.9
The response to a successful request MUST include a Location
header containing the URL for the new version created by the
checkin.
The response MUST include a Cache-Control:no-cache header.
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Preconditions:
(DAV:cannot-merge-checked-out-resource): The DAV:source element
MUST NOT identify a checked-out resource. If the DAV:source
element identifies a collection, the collection MUST NOT have a
member that is a checked-out resource.
(DAV:checkout-not-allowed): If DAV:no-checkout is specified in the
request body, it MUST be possible to perform the merge without
checking out any of the merge targets.
All preconditions of the CHECKOUT operation apply to the checkouts
performed by the request.
Postconditions:
(DAV:ancestor-version): If a merge target is a version-controlled
or checked-out resource whose DAV:checked-in version or
DAV:checked-out version is the merge source or is a descendant of
the merge source, the merge target MUST NOT have been modified by
the MERGE.
(DAV:descendant-version): If the merge target was a checked-in
version-controlled resource whose DAV:checked-in version was an
ancestor of the merge source, an UPDATE operation MUST have been
applied to the merge target to set its content and dead properties
to be those of the merge source. If the UPDATE method is not
supported, the merge target MUST have been checked out, the
content and dead properties of the merge target MUST have been set
to those of the merge source, and the merge source MUST have been
added to the DAV:auto-merge-set of the merge target. The merge
target MUST appear in a DAV:response XML element in the response
body.
(DAV:checked-out-for-merge): If the merge target was a checked-in
version-controlled resource whose DAV:checked-in version was
neither a descendant nor an ancestor of the merge source, a
CHECKOUT MUST have been applied to the merge target. All XML
elements in the DAV:merge XML element that could appear in a
DAV:checkout XML element MUST have been used as arguments to the
CHECKOUT request. The merge target MUST appear in a DAV:response
XML element in the response body.
(DAV:update-merge-set): If the DAV:checked-out version of the
merge target is neither equal to nor a descendant of the merge
source, the merge source MUST be added to either the DAV:merge-set
or the DAV:auto-merge-set of the merge target. The merge target
MUST appear in a DAV:response XML element in the response body.
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If a merge source has been added to the DAV:auto-merge-set, the
content and dead properties of the merge target MUST have been
modified by the server to reflect the result of a logical merge of
the merge source and the merge target. If a merge source has been
added to the DAV:merge-set, the content and dead properties of the
merge target MUST NOT have been modified by the server. If
DAV:no-auto-merge is specified in the request body, the merge
source MUST NOT have been added to the DAV:auto-merge-set.
(DAV:report-properties): If DAV:prop is specified in the request
body, the properties specified in the DAV:prop element MUST be
reported in the DAV:response elements in the response body.
11.2.1 Example - MERGE
>>REQUEST
MERGE /ws/public HTTP/1.1
Host: www.webdav.org
Content-type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:merge xmlns:D="DAV:">
<D:source>
<D:href>http://www.webdav.org/ws/dev/sally</D:href>
</D:source>
</D:merge>
>>RESPONSE
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Cache-Control: no-cache
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>http://www.webdav.org/ws/public/src/parse.c</D:href>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
<D:response>
<D:href>http://www.webdav.org/ws/public/doc/parse.html</D:href>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
</D:multistatus>
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In this example, the DAV:checked-in versions from the workspace
http://www.webdav.org/ws/dev/sally are merged into the version-
controlled resources in the workspace
http://www.webdav.org/ws/public. The resources
/ws/public/src/parse.c and /ws/public/doc/parse.html were modified by
the request.
11.3 DAV:merge-preview Report
A merge preview describes the changes that would result if the
versions specified by the DAV:source element in the request body were
to be merged into the resource identified by the request-URL
(commonly, a collection).
Marshalling:
The request body MUST be a DAV:merge-preview XML element.
<!ELEMENT merge-preview (source)>
<!ELEMENT source (href)>
The response body for a successful request MUST be a
DAV:merge-preview-report XML element.
<!ELEMENT merge-preview-report
(update-preview | conflict-preview | ignore-preview)*>
A DAV:update-preview element identifies a merge target whose
DAV:checked-in property would change as a result of the MERGE, and
identifies the merge source for that merge target.
<!ELEMENT update-preview (target, version)>
<!ELEMENT target (href)>
<!ELEMENT version (href)>
A DAV:conflict-preview element identifies a merge target that
requires a merge.
<!ELEMENT conflict-preview (target, common-ancestor, version)>
A DAV:common-ancestor element identifies the version that is a
common ancestor of both the merge source and the DAV:checked-in or
DAV:checked-out version of the merge target.
<!ELEMENT common-ancestor (href)>
A DAV:ignore-preview element identifies a version that has no
merge target and therefore would be ignored by the merge.
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<!ELEMENT ignore-preview (version)>
11.3.1 Example - DAV:merge-preview Report
>>REQUEST
REPORT /ws/public HTTP/1.1
Host: www.webdav.org
Content-type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:merge-preview xmlns:D="DAV:">
<D:source>
<D:href>http://www.webdav.org/ws/dev/fred</D:href>
</D:source>
</D:merge-preview>
>>RESPONSE
HTTP/1.1 200 OK
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:merge-preview-report xmlns:D="DAV:">
<D:conflict-preview>
<D:target>
<D:href>http://www.webdav.org/ws/public/foo.html</D:href>
</D:target>
<D:common-ancestor>
<D:href>http://repo.webdav.org/his/23/ver/18</D:href>
</D:common-ancestor>
<D:version>
<D:href>http://repo.webdav.org/his/23/ver/42</D:href>
</D:version>
</D:conflict-preview>
<D:update-preview>
<D:target>
<D:href>http://www.webdav.org/ws/public/bar.html</D:href>
</D:target>
<D:version>
<D:href>http://www.repo/his/42/ver/3</D:href>
</D:version>
</D:update-preview>
</D:merge-preview-report>
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In this example, the merge preview report indicates that version
/his/23/ver/42 would be merged in /ws/public/foo.html, and version
/his/42/ver/3 would update /ws/public/bar.html if the workspace
http://www.webdav.org/ws/dev/fred was merged into the workspace
http://www.webdav.org/ws/public.
11.4 Additional OPTIONS Semantics
If the server supports the merge feature, it MUST include "merge" as
a field in the DAV response header from an OPTIONS request on any
resource that supports any versioning properties, reports, or
methods.
11.5 Additional DELETE Semantics
Additional Postconditions:
(DAV:delete-version-reference): If a version is deleted, any
reference to that version in a DAV:merge-set or DAV:auto-merge-set
property MUST be removed.
11.6 Additional CHECKIN Semantics
Additional Preconditions:
(DAV:merge-must-be-complete): The DAV:merge-set and DAV:auto-
merge-set of the checked-out resource MUST be empty or not exist.
12 Baseline Feature
A configuration is a set of resources that consists of a root
collection and all members of that root collection except those
resources that are members of another configuration. A configuration
that contains a large number of resources can consume a large amount
of space on a server. This can make it prohibitively expensive to
remember the state of an existing configuration by creating a
Depth:infinity copy of its root collection.
A baseline is a version resource that captures the state of each
version-controlled member of a configuration. A baseline history is
a version history whose versions are baselines. New baselines are
created by checking out and then checking in a special kind of
version-controlled resource called a version-controlled
configuration.
A collection that is under baseline control is called a baseline-
controlled collection. In order to allow efficient baseline
implementation, the state of a baseline of a collection is limited to
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be a set of versions and their names relative to the collection, and
the operations on a baseline are limited to the creation of a
baseline from a collection, and restoring or merging the baseline
back into a collection. A server MAY automatically put a collection
under baseline control when it is created, or a client can use the
BASELINE-CONTROL method to put a specified collection under baseline
control.
As a configuration gets large, it is often useful to break it up into
a set of smaller configurations that form the logical "components" of
that configuration. In order to capture the fact that a baseline of
a configuration is logically extended by a component configuration
baseline, the component configuration baseline is captured as a
"subbaseline" of the baseline.
The root collection of a configuration is unconstrained with respect
to its relationship to the root collection of any of its components.
In particular, the root collection of a configuration can have a
member that is the root collection of one of its components (e.g.,
configuration /sys/x can have a component /sys/x/foo), can be a
member of the root collection of one of its components (e.g.,
configuration /sys/y/z can have a component /sys/y), or neither
(e.g., configuration /sys/x can have a component /comp/bar).
12.1 Version-Controlled Configuration Properties
Since a version-controlled configuration is a version-controlled
resource, it has all the properties of a version-controlled resource.
In addition, the baseline feature introduces the following REQUIRED
property for a version-controlled configuration.
12.1.1 DAV:baseline-controlled-collection (protected)
This property identifies the collection that contains the version-
controlled resources whose DAV:checked-in versions are being tracked
by this version-controlled configuration. The DAV:version-
controlled-configuration of the DAV:baseline-controlled-collection of
a version-controlled configuration MUST identify that version-
controlled configuration.
<!ELEMENT baseline-controlled-collection (href)>
12.2 Checked-Out Configuration Properties
Since a checked-out configuration is a checked-out resource, it has
all the properties of a checked-out resource. In addition, the
baseline feature introduces the following REQUIRED property for a
checked-out configuration.
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12.2.1 DAV:subbaseline-set
This property determines the DAV:subbaseline-set property of the
baseline that results from checking in this resource.
A server MAY reject attempts to modify the DAV:subbaseline-set of a
checked-out configuration.
<!ELEMENT subbaseline-set (href*)>
12.3 Baseline Properties
The DAV:resourcetype of a baseline MUST be DAV:baseline. Since a
baseline is a version resource, it has all the properties of a
version resource. In addition, the baseline feature introduces the
following REQUIRED properties for a baseline.
12.3.1 DAV:baseline-collection (protected)
This property contains a server-defined URL for a collection, where
each member of this collection MUST either be a version-controlled
resource with the same DAV:checked-in version and relative name as a
version-controlled member of the baseline-controlled collection at
the time the baseline was created, or be a collection needed to
provide the relative name for a version-controlled resource.
<!ELEMENT baseline-collection (href)>
12.3.2 DAV:subbaseline-set (protected)
The URLs in the DAV:subbaseline-set property MUST identify a set of
other baselines. The subbaselines of a baseline are the baselines
identified by its DAV:subbaseline-set and all subbaselines of the
baselines identified by its DAV:subbaseline-set.
<!ELEMENT subbaseline-set (href*)>
12.4 Additional Resource Properties
The baseline feature introduces the following REQUIRED property for a
resource.
12.4.1 DAV:version-controlled-configuration (computed)
If the resource is a member of a version-controlled configuration
(i.e. the resource is a collection under baseline control or is a
member of a collection under baseline control), this property
identifies that version-controlled configuration.
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<!ELEMENT version-controlled-configuration (href)>
12.5 Additional Workspace Properties
The baseline feature introduces the following REQUIRED property for a
workspace.
12.5.1 DAV:baseline-controlled-collection-set (computed)
This property identifies each member of the workspace that is a
collection under baseline control (as well as the workspace itself,
if it is under baseline control).
<!ELEMENT baseline-controlled-collection-set (href*)>
12.6 BASELINE-CONTROL Method
A collection can be placed under baseline control with a
BASELINE-CONTROL request. When a collection is placed under baseline
control, the DAV:version-controlled-configuration property of the
collection is set to identify a new version-controlled configuration.
This version-controlled configuration can be checked out and then
checked in to create a new baseline for that collection.
If a baseline is specified in the request body, the DAV:checked-in
version of the new version-controlled configuration will be that
baseline, and the collection is initialized to contain version-
controlled members whose DAV:checked-in versions and relative names
are determined by the specified baseline.
If no baseline is specified, a new baseline history is created
containing a baseline that captures the state of the version-
controlled members of the collection, and the DAV:checked-in version
of the version-controlled configuration will be that baseline.
Marshalling:
If a request body is included, it MUST be a DAV:baseline-control
XML element.
<!ELEMENT baseline-control ANY>
ANY value: A sequence of elements with at most one DAV:baseline
element.
<!ELEMENT baseline (href)>
If a response body for a successful request is included, it MUST
be a DAV:baseline-control-response XML element.
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<!ELEMENT baseline-control-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:version-controlled-configuration-must-not-exist): The
DAV:version-controlled-configuration property of the collection
identified by the request-URL MUST not exist.
(DAV:must-be-baseline): The DAV:href of the DAV:baseline element
in the request body MUST identify a baseline.
(DAV:must-have-no-version-controlled-members): If a DAV:baseline
element is specified in the request body, the collection
identified by the request-URL MUST have no version-controlled
members.
(DAV:one-baseline-controlled-collection-per-history-per-
workspace): If the request-URL identifies a workspace or a member
of a workspace, and if a baseline is specified in a DAV:baseline
element in the request body, then there MUST NOT be another
collection in that workspace whose DAV:version-controlled-
configuration property identifies a version-controlled
configuration for the baseline history of that baseline.
Postconditions:
(DAV:create-version-controlled-configuration): A new version-
controlled configuration is created, whose DAV:baseline-
controlled-collection property identifies the collection.
(DAV:reference-version-controlled-configuration): The
DAV:version-controlled-configuration of the collection identifies
the new version-controlled configuration.
(DAV:select-existing-baseline): If the request body specifies a
baseline, the DAV:checked-in property of the new version-
controlled configuration MUST have been set to identify this
baseline. A version-controlled member of the collection will be
created for each version in the baseline, where the version-
controlled member will have the content and dead properties of
that version, and will have the same name relative to the
collection as the corresponding version-controlled resource had
when the baseline was created. Any nested collections that are
needed to provide the appropriate name for a version-controlled
member will be created.
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(DAV:create-new-baseline): If no baseline is specified in the
request body, the request MUST have created a new baseline history
at a server-defined URL, and MUST have created a new baseline in
that baseline history. The DAV:baseline-collection of the new
baseline MUST identify a collection whose members have the same
relative name and DAV:checked-in version as the version-controlled
members of the request collection. The DAV:checked-in property of
the new version-controlled configuration MUST identify the new
baseline.
12.6.1 Example - BASELINE-CONTROL
>>REQUEST
BASELINE-CONTROL /src HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:baseline-control xmlns:D="DAV:">
<D:href>http://www.webdav.org/repo/blh/13/ver/8</D:href>
</D:baseline-control>
>>RESPONSE
HTTP/1.1 200 OK
Cache-Control: no-cache
Content-Length: 0
Clemm, et al. Standards Track PAGE 82
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In this example, the collection /src is placed under baseline
control, and is populated with members from an existing baseline. A
new version-controlled configuration (/repo/vcc/128) is created and
associated with /src, and /src is initialized with version-controlled
members whose DAV:checked-in versions are those selected by the
DAV:baseline-collection (/repo/bc/15) of the specified baseline
(/repo/blh/13/ver/8). The following diagram illustrates the
resulting state on the server.
+-------------------------------------+
|Baseline-Controlled Collection |<------+
|/src | |
|-------------------------------------| |
|DAV:version-controlled-configuration +---+ |
+-------------------------------------+ | |
| |
| |
+-------------------------------------+ | |
|Version-Controlled Configuration |<--+ |
|/repo/vcc/128 | |
|-------------------------------------| |
|DAV:baseline-controlled-collection +-------+
|-------------------------------------|
|DAV:checked-in +-------+
+-------------------------------------+ |
|DAV:version-history +---+ |
+-------------------------------------+ | |
| |
| |
+------------------------+ | |
|Baseline History |<---------------+ |
|/repo/blh/13 | |
|------------------------+ |
|DAV:version-set +----------------+ |
+------------------------+ | | | | |
v | v v |
| |
+------------------------+ | |
|Baseline |<-------+-----------+
|/repo/blh/13/ver/8 |
|------------------------+ +--------------+
|DAV:baseline-collection +---->|Collection |
+------------------------+ |/repo/bc/15 |
+--------------+
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In order to create new baselines of /src, /repo/vcc/128 can be
checked out, new versions can be created or selected by the version-
controlled members of /src, and then /repo/vcc/128 can be checked in
to capture the current state of those version-controlled members.
12.7 DAV:compare-baseline Report
A DAV:compare-baseline report contains the differences between the
baseline identified by the request-URL (the "request baseline") and
the baseline specified in the request body (the "compare baseline").
Marshalling:
The request body MUST be a DAV:compare-baseline XML element.
<!ELEMENT compare-baseline (href)>
The response body for a successful request MUST be a DAV:compare-
baseline-report XML element.
<!ELEMENT compare-baseline-report
(added-version | deleted-version | changed-version)*>
A DAV:added-version element identifies a version that is the
DAV:checked-in version of a member of the DAV:baseline-collection
of the compare baseline, but no version in the version history of
that version is the DAV:checked-in version of a member of the
DAV:baseline-collection of the request baseline.
<!ELEMENT added-version (href)>
A DAV:deleted-version element identifies a version that is the
DAV:checked-in version of a member of the DAV:baseline-collection
of the request baseline, but no version in the version history of
that version is the DAV:checked-in version of a member of the
DAV:baseline-collection of the compare baseline.
<!ELEMENT deleted-version (href)>
A DAV:changed-version element identifies two different versions
from the same version history that are the DAV:checked-in version
of the DAV:baseline-collection of the request baseline and the
compare baseline, respectively.
<!ELEMENT changed-version (href, href)>
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Preconditions:
(DAV:must-be-baseline): The DAV:href in the request body MUST
identify a baseline.
(DAV:baselines-from-same-history): A server MAY require that the
baselines being compared be from the same baseline history.
12.7.1 Example - DAV:compare-baseline Report
>>REQUEST
REPORT /bl-his/12/bl/14 HTTP/1.1
Host: repo.webdav.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:compare-baseline xmlns:D="DAV:">
<D:href>http://repo.webdav.org/bl-his/12/bl/15</D:href>
</D:compare-baseline>
>>RESPONSE
HTTP/1.1 200 OK
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:compare-baseline-report xmlns:D="DAV:">
<D:added-version>
<D:href>http://repo.webdav.org/his/23/ver/8</D:href>
</D:added-version>
<D:changed-version>
<D:href>http://repo.webdav.org/his/29/ver/12</D:href>
<D:href>http://repo.webdav.org/his/29/ver/19</D:href>
</D:changed-version>
<D:deleted-version>
<D:href>http://repo.webdav.org/his/12/ver/4</D:href>
</D:deleted-version>
</D:compare-baseline-report>
In this example, the differences between baseline 14 and baseline 15
of http://repo.webdav.org/bl-his/12 are identified.
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12.8 Additional OPTIONS Semantics
If a server supports the baseline feature, it MUST include "baseline"
as a field in the DAV response header from an OPTIONS request on any
resource that supports any versioning properties, reports, or
methods.
12.9 Additional MKCOL Semantics
Additional Postconditions:
If a server automatically puts a newly created collection under
baseline control, all postconditions for BASELINE-CONTROL apply to
the MKCOL.
12.10 Additional COPY Semantics
Additional Postconditions:
If the request creates a new collection at the Destination, and a
server automatically puts a newly created collection under
baseline control, all postconditions for BASELINE-CONTROL apply to
the COPY.
12.11 Additional CHECKOUT Semantics
Additional Preconditions:
(DAV:must-not-update-baseline-collection): If the request-URL
identifies a member of the configuration rooted at the
DAV:baseline-collection of a baseline, the request MUST fail.
12.12 Additional CHECKIN Semantics
Additional Preconditions:
(DAV:no-checked-out-baseline-controlled-collection-members): If
the request-URL identifies a version-controlled configuration, all
version-controlled members of the DAV:baseline-controlled-
collection of the version-controlled configuration MUST be
checked-in.
(DAV:one-version-per-history-per-baseline): If the request-URL
identifies a version-controlled configuration, the set of versions
selected by that version-controlled configuration MUST contain at
most one version from any version history, where a version is
selected by a version-controlled configuration if the version is
identified by the DAV:checked-in property of any member of the
Clemm, et al. Standards Track PAGE 86
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configuration rooted at the DAV:baseline-controlled collection of
that version-controlled configuration, or is identified by the
DAV:checked-in property of any member of the configuration rooted
at the DAV:baseline-collection of any subbaseline of that
version-controlled configuration.
(DAV:cannot-modify-version-controlled-configuration): If the
request-URL identifies a version-controlled member of a baseline-
controlled collection whose version-controlled configuration is
checked-in, the request MUST fail unless the DAV:auto-version
property of the version-controlled configuration will
automatically check out that version-controlled configuration when
it is modified.
Additional Postconditions:
(DAV:create-baseline-collection): If the request-URL identifies a
version-controlled configuration, the DAV:baseline-collection of
the new baseline identifies a collection whose members have the
same relative name and DAV:checked-in version as the members of
the DAV:baseline-controlled-collection of the version-controlled
configuration at the time of the request.
(DAV:modify-configuration): If the request-URL identifies a
version-controlled member of a baseline-controlled collection,
this is a modification to the version-controlled configuration of
that baseline-controlled collection, and standard auto-versioning
semantics apply.
12.13 Additional UPDATE Semantics
Additional Preconditions:
(DAV:baseline-controlled-members-must-be-checked-in): If the
request-URL identifies a version-controlled configuration, then
all version-controlled members of the DAV:baseline-controlled-
collection of that version-controlled configuration MUST be
checked-in.
(DAV:must-not-update-baseline-collection): If the request-URL
identifies a member of the configuration rooted at the
DAV:baseline-collection of a baseline, the request MUST fail.
(DAV:cannot-modify-version-controlled-configuration): If the
request updates the DAV:checked-in property of any version-
controlled member of a baseline-controlled collection whose
version-controlled configuration is checked-in, the request MUST
Clemm, et al. Standards Track PAGE 87
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fail unless the DAV:auto-version property of the version-
controlled configuration will automatically check out that
version-controlled configuration when it is modified.
Additional Postconditions:
(DAV:set-baseline-controlled-collection-members): If the request
updated the DAV:checked-in property of a version-controlled
configuration, then the version-controlled members of the
DAV:baseline-controlled-collection of that version-controlled
configuration MUST have been updated so that they have the same
relative name, content, and dead properties as the members of the
DAV:baseline-collection of the baseline. In particular:
- A version-controlled member for a given version history MUST
have been deleted if there is no version-controlled member for
that version history in the DAV:baseline-collection of the
baseline.
- A version-controlled member for a given version history MUST
have been renamed if its name relative to the baseline-
controlled collection is different from that of the version-
controlled member for that version history in the
DAV:baseline-collection of the baseline.
- A new version-controlled member MUST have been created for each
member of the DAV:baseline-collection of the baseline for which
there is no corresponding version-controlled member in the
baseline-controlled collection.
- An UPDATE request MUST have been applied to each version-
controlled member for a given version history whose
DAV:checked-in version is not the same as that of the version-
controlled member for that version history in the
DAV:baseline-collection of the baseline.
(DAV:update-subbaselines): If the request updated a version-
controlled configuration whose DAV:baseline-controlled-collection
contains a baseline-controlled member for one of the subbaselines
of the request baseline, then the DAV:checked-in property of the
version-controlled configuration of that baseline-controlled
member MUST have been updated to be that subbaseline. If the
request updated a version-controlled configuration whose
DAV:baseline-controlled-collection is a member of a workspace that
contains a baseline-controlled member for one of the subbaselines
of the request baseline, then the DAV:checked-in property of the
version-controlled configuration of that baseline-controlled
member MUST have been updated to be that subbaseline.
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(DAV:modify-configuration): If the request updated the
DAV:checked-in property of any version-controlled member of a
baseline-controlled collection, and if this DAV:checked-in
property differs from the DAV:checked-in property of the
corresponding version-controlled member of the DAV:baseline-
collection of the DAV:checked-in baseline of the DAV:version-
controlled-configuration of the baseline-controlled collection,
then this is a modification to that version-controlled
configuration, and standard auto-versioning semantics apply.
12.14 Additional MERGE Semantics
If the merge source is a baseline, the merge target is a version-
controlled configuration for the baseline history of that baseline,
where the baseline-controlled collection of that version-controlled
configuration is a member of the collection identified by the
request-URL.
Additional Preconditions:
(DAV:must-not-update-baseline-collection): Same semantics as
UPDATE (see Section 12.13).
(DAV:cannot-modify-version-controlled-configuration): Same
semantics as UPDATE (see Section 12.13).
Additional Postconditions:
(DAV:merge-baseline): If the merge target is a version-controlled
configuration whose DAV:checked-out baseline is not a descendant
of the merge baseline, then the merge baseline MUST have been
added to the DAV:auto-merge-set of a version-controlled
configuration. The DAV:checked-in version of each member of the
DAV:baseline-collection of that baseline MUST have been merged
into the DAV:baseline-controlled-collection of that version-
controlled configuration.
(DAV:merge-subbaselines): If the merge target is a version-
controlled configuration whose DAV:baseline-controlled-collection
contains a baseline-controlled member for one of the subbaselines
of the merge baseline, then that subbaseline MUST have been merged
into the version-controlled configuration of that baseline-
controlled member. If the merge target is a version-controlled
configuration whose DAV:baseline-controlled-collection is a member
of a workspace that contains a baseline-controlled member for one
of the subbaselines of the merge baseline, then that subbaseline
MUST have been merged into the version-controlled configuration of
that baseline-controlled member.
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RFC 3253 Versioning Extensions to WebDAV March 2002
(DAV:set-baseline-controlled-collection-members): Same semantics
as UPDATE (see Section 12.13).
(DAV:modify-configuration): Same semantics as UPDATE (see Section
12.13).
13 Activity Feature
An activity is a resource that selects a set of versions that are on
a single "line of descent", where a line of descent is a sequence of
versions connected by successor relationships. If an activity
selects versions from multiple version histories, the versions
selected in each version history must be on a single line of descent.
A common problem that motivates the use of activities is that it is
often desirable to perform several different logical changes in a
single workspace, and then selectively merge a subset of those
logical changes to other workspaces. An activity can be used to
represent a single logical change, where an activity tracks all the
resources that were modified to effect that single logical change.
When a version-controlled resource is checked out, the user specifies
which activity should be associated with a new version that will be
created when that version-controlled resource is checked in. It is
then possible to select a particular logical change for merging into
another workspace, by specifying the appropriate activity in a MERGE
request.
Another common problem is that although a version-controlled resource
may need to have multiple lines of descent, all work done by members
of a given team must be on a single line of descent (to avoid merging
between team members). An activity resource provides the mechanism
for addressing this problem. When a version-controlled resource is
checked out, a client can request that an existing activity be used
or that a new activity be created. Activity semantics then ensure
that all versions in a given version history that are associated with
an activity are on a single line of descent. If all members of a
team share a common activity (or sub-activities of a common
activity), then all changes made by members of that team will be on a
single line of descent.
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The following diagram illustrates activities. Version V5 is the
latest version of foo.html selected by activity Act-2, and version V8
is the latest version of bar.html selected by activity Act-2.
foo.html History bar.html History
+---+ +---+
Act-1| |V1 Act-1| |V6
+---+ +---+
| |
| |
+---+ +---+
Act-1| |V2 Act-2| |V7
+---+ +---+
/ \ |
/ \ |
+---+ +---+ +---+
Act-1| |V3 Act-2| |V4 Act-2| |V8
+---+ +---+ +---+
| |
| |
+---+ +---+
Act-2| |V5 Act-3| |V9
+---+ +---+
Activities appear under a variety of names in existing versioning
systems. When an activity is used to capture a logical change, it is
commonly called a "change set". When an activity is used to capture
a line of descent, it is commonly called a "branch". When a system
supports both branches and change sets, it is often useful to require
that a particular change set occur on a particular branch. This
relationship can be captured by making the change set activity be a
"subactivity" of the branch activity.
13.1 Activity Properties
The DAV:resourcetype of an activity MUST be DAV:activity.
The activity feature introduces the following REQUIRED properties for
an activity.
13.1.1 DAV:activity-version-set (computed)
This property identifies each version whose DAV:activity-set property
identifies this activity. Multiple versions of a single version
history can be selected by an activity's DAV:activity-version-set
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property, but all DAV:activity-version-set versions from a given
version history must be on a single line of descent from the root
version of that version history.
<!ELEMENT activity-version-set (href*)>
13.1.2 DAV:activity-checkout-set (computed)
This property identifies each checked-out resource whose
DAV:activity-set identifies this activity.
<!ELEMENT activity-checkout-set (href*)>
13.1.3 DAV:subactivity-set
This property identifies each activity that forms a part of the
logical change being captured by this activity. An activity behaves
as if its DAV:activity-version-set is extended by the DAV:activity-
version-set of each activity identified in the DAV:subactivity-set.
In particular, the versions in this extended set MUST be on a single
line of descent, and when an activity selects a version for merging,
the latest version in this extended set is the one that will be
merged.
A server MAY reject attempts to modify the DAV:subactivity-set of an
activity.
<!ELEMENT subactivity-set (href*)>
13.1.4 DAV:current-workspace-set (computed)
This property identifies each workspace whose DAV:current-activity-
set identifies this activity.
<!ELEMENT current-workspace-set (href*)>
13.2 Additional Version Properties
The activity feature introduces the following REQUIRED property for a
version.
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13.2.1 DAV:activity-set
This property identifies the activities that determine to which
logical changes this version contributes, and on which lines of
descent this version appears. A server MAY restrict the
DAV:activity-set to identify a single activity. A server MAY refuse
to allow the value of the DAV:activity-set property of a version to
be modified.
<!ELEMENT activity-set (href*)>
13.3 Additional Checked-Out Resource Properties
The activity feature introduces the following REQUIRED properties for
a checked-out resource.
13.3.1 DAV:unreserved
This property of a checked-out resource indicates whether the
DAV:activity-set of another checked-out resource associated with the
version history of this version-controlled resource can have an
activity that is in the DAV:activity-set property of this checked-out
resource.
A result of the requirement that an activity must form a single line
of descent through a given version history is that if multiple
checked-out resources for a given version history are checked out
unreserved into a single activity, only the first CHECKIN will
succeed. Before another of these checked-out resources can be
checked in, the user will first have to merge into that checked-out
resource the latest version selected by that activity from that
version history, and then modify the DAV:predecessor-set of that
checked-out resource to identify that version.
<!ELEMENT unreserved (#PCDATA)>
PCDATA value: boolean
13.3.2 DAV:activity-set
This property of a checked-out resource determines the DAV:activity-
set property of the version that results from checking in this
resource.
13.4 Additional Workspace Properties
The activity feature introduces the following REQUIRED property for a
workspace.
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13.4.1 DAV:current-activity-set
This property identifies the activities that currently are being
performed in this workspace. When a member of this workspace is
checked out, if no activity is specified in the checkout request, the
DAV:current-activity-set will be used. This allows an activity-
unaware client to update a workspace in which activity tracking is
required. The DAV:current-activity-set MAY be restricted to identify
at most one activity.
<!ELEMENT current-activity-set (href*)>
13.5 MKACTIVITY Method
A MKACTIVITY request creates a new activity resource. A server MAY
restrict activity creation to particular collections, but a client
can determine the location of these collections from a DAV:activity-
collection-set OPTIONS request.
Marshalling:
If a request body is included, it MUST be a DAV:mkactivity XML
element.
<!ELEMENT mkactivity ANY>
If a response body for a successful request is included, it MUST
be a DAV:mkactivity-response XML element.
<!ELEMENT mkactivity-response ANY>
The response MUST include a Cache-Control:no-cache header.
Preconditions:
(DAV:resource-must-be-null): A resource MUST NOT exist at the
request-URL.
(DAV:activity-location-ok): The request-URL MUST identify a
location where an activity can be created.
Postconditions:
(DAV:initialize-activity): A new activity exists at the request-
URL. The DAV:resourcetype of the activity MUST be DAV:activity.
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13.5.1 Example - MKACTIVITY
>>REQUEST
MKACTIVITY /act/test-23 HTTP/1.1
Host: repo.webdav.org
Content-Length: 0
>>RESPONSE
HTTP/1.1 201 Created
Cache-Control: no-cache
In this example, a new activity is created at
http://repo.webdav.org/act/test-23.
13.6 DAV:latest-activity-version Report
The DAV:latest-activity-version report can be applied to a version
history to identify the latest version that is selected from that
version history by a given activity.
Marshalling:
The request body MUST be a DAV:latest-activity-version XML
element.
<!ELEMENT latest-activity-version (href)>
The response body for a successful request MUST be a DAV:latest-
activity-version-report XML element.
<!ELEMENT latest-activity-version-report (href)>
The DAV:href of the response body MUST identify the version of the
given version history that is a member of the DAV:activity-
version-set of the given activity and has no descendant that is a
member of the DAV:activity-version-set of that activity.
Preconditions:
(DAV:must-be-activity): The DAV:href in the request body MUST
identify an activity.
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13.7 Additional OPTIONS Semantics
If the server supports the activity feature, it MUST include
"activity" as a field in the DAV response header from an OPTIONS
request on any resource that supports any versioning properties,
reports, or methods.
A DAV:activity-collection-set element MAY be included in the request
body to identify collections that may contain activity resources.
Additional Marshalling:
If an XML request body is included, it MUST be a DAV:options XML
element.
<!ELEMENT options ANY>
ANY value: A sequence of elements with at most one
DAV:activity-collection-set element.
If an XML response body for a successful request is included, it
MUST be a DAV:options-response XML element.
<!ELEMENT options-response ANY>
ANY value: A sequence of elements with at most one
DAV:activity-collection-set element.
<!ELEMENT activity-collection-set (href*)>
If DAV:activity-collection-set is included in the request body,
the response body for a successful request MUST contain a
DAV:activity-collection-set element identifying collections that
may contain activities. An identified collection MAY be the root
collection of a tree of collections, all of which may contain
activities. Since different servers can control different parts
of the URL namespace, different resources on the same host MAY
have different DAV:activity-collection-set values. The identified
collections MAY be located on different hosts from the resource.
13.8 Additional DELETE Semantics
Additional Postconditions:
(DAV:delete-activity-reference): If an activity is deleted, any
reference to that activity in a DAV:activity-set,
DAV:subactivity-set, or DAV:current-activity-set MUST be removed.
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13.9 Additional MOVE Semantics
Additional Postconditions:
(DAV:update-checked-out-reference): If a checked-out resource is
moved, any reference to that resource in a DAV:activity-checkout-
set property MUST be updated to refer to the new location of that
resource.
(DAV:update-activity-reference): If the request-URL identifies an
activity, any reference to that activity in a DAV:activity-set,
DAV:subactivity-set, or DAV:current-activity-set MUST be updated
to refer to the new location of that activity.
(DAV:update-workspace-reference): If the request-URL identifies a
workspace, any reference to that workspace in a DAV:current-
workspace-set property MUST be updated to refer to the new
location of that workspace.
13.10 Additional CHECKOUT Semantics
A CHECKOUT request MAY specify the DAV:activity-set for the checked-
out resource.
Additional Marshalling:
<!ELEMENT checkout ANY> ANY value: A sequence of elements with at
most one DAV:activity-set and at most one DAV:unreserved.
<!ELEMENT activity-set (href+ | new)>
<!ELEMENT new EMPTY>
<!ELEMENT unreserved EMPTY>
Additional Preconditions:
(DAV:one-checkout-per-activity-per-history): If there is a request
activity set, unless DAV:unreserved is specified, another checkout
from a version of that version history MUST NOT select an activity
in that activity set.
(DAV:linear-activity): If there is a request activity set, unless
DAV:unreserved is specified, the selected version MUST be a
descendant of all other versions of that version history that
select that activity.
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Additional Postconditions:
(DAV:initialize-activity-set): The DAV:activity-set of the
checked-out resource is set as follows:
- If DAV:new is specified as the DAV:activity-set in the request
body, then a new activity created by the server is used.
- Otherwise, if activities are specified in the request body,
then those activities are used.
- Otherwise, if the version-controlled resource is a member of a
workspace and the DAV:current-activity-set of the workspace is
set, then those activities are used.
- Otherwise, the DAV:activity-set of the DAV:checked-out version
is used.
(DAV:initialize-unreserved): If DAV:unreserved was specified in
the request body, then the DAV:unreserved property of the
checked-out resource MUST be "true".
13.10.1 Example - CHECKOUT with an activity
>>REQUEST
CHECKOUT /ws/public/foo.html HTTP/1.1
Host: www.webdav.org
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:checkout xmlns:D="DAV:">
<D:activity-set>
<D:href>http://repo.webdav.org/act/fix-bug-23</D:href>
</D:activity-set>
</D:checkout>
>>RESPONSE
HTTP/1.1 200 OK
Cache-Control: no-cache
In this example, the CHECKOUT is being performed in the
http://repo.webdav.org/act/fix-bug-23 activity.
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13.11 Additional CHECKIN Semantics
Additional Preconditions:
(DAV:linear-activity): Any version which is in the version history
of the checked-out resource and whose DAV:activity-set identifies
an activity from the DAV:activity-set of the checked-out resource
MUST be an ancestor of the checked-out resource.
(DAV:atomic-activity-checkin): If the request-URL identifies an
activity, the server MAY fail the request if any of the checked-
out resources in the DAV:activity-checkout-set of either that
activity or any subactivity of that activity cannot be checked in.
Additional Postconditions:
(DAV:initialize-activity-set): The DAV:activity-set of the new
version MUST have been initialized to be the same as the
DAV:activity-set of the checked-out resource.
(DAV:activity-checkin): If the request-URL identified an activity,
the server MUST have successfully applied the CHECKIN request to
each checked-out resource in the DAV:activity-checkout-set of both
that activity and any subactivity of that activity.
13.12 Additional MERGE Semantics
If the DAV:source element of the request body identifies an activity,
then for each version history containing a version selected by that
activity, the latest version selected by that activity is a merge
source. Note that the versions selected by an activity are the
versions in its DAV:activity-version-set unioned with the versions
selected by the activities in its DAV:subactivity-set.
Additional Marshalling:
<!ELEMENT checkin-activity EMPTY>
Additional Postconditions:
(DAV:checkin-activity): If DAV:checkin-activity is specified in
the request body, and if the DAV:source element in the request
body identifies an activity, a CHECKIN request MUST have been
successfully applied to that activity before the merge sources
were determined.
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14 Version-Controlled-Collection Feature
As with any versionable resource, when a collection is put under
version control, a version history resource is created to contain
versions for that version-controlled collection. In order to
preserve standard versioning semantics (a version of a collection
should not be modifiable), a collection version only records
information about the version-controlled bindings of that collection.
In order to cleanly separate a modification to the namespace from a
modification to content or dead properties, a version of a collection
has no members, but instead records in its DAV:version-controlled-
binding-set property the binding name and version history resource of
each version-controlled internal member of that collection. If,
instead, a collection version contained bindings to other versions,
creating a new version of a resource would require creating a new
version of all the collection versions that contain that resource,
which would cause activities to become entangled. For example,
suppose a "feature-12" activity created a new version of /x/y/a.html.
If a collection version contained bindings to versions of its
members, a new version of /x/y would have to be created to contain
the new version of /x/y/a.html, and a new version of /x would have to
be created to contain the new version of /x/y. Now suppose a
"bugfix-47" activity created a new version of /x/z/b.html. Again, a
new version of /x/z and a new version of /x would have to be created
to contain the new version of /x/y/b.html. But now it is impossible
to merge just "bugfix-47" into another workspace without "feature-
12", because the version of /x that contains the desired version of
/x/z/b.html also contains version of /x/y/a.html created for
"feature-12". If, instead, a collection version just records the
binding name and version history resource of each version-controlled
internal member, changing the version selected by a member of that
collection would not require a new version of the collection. The
new version is still in the same version history so no new collection
version is required, and "feature-12" and "bugfix-47" would not
become entangled.
In the following example, there are three version histories, named
VH14, VH19, and VH24, where VH14 contains versions of a collection.
The version-controlled collection /x has version V2 of version
history VH14 as its DAV:checked-in version. Since V2 has recorded
two version controlled bindings, one with binding name "a" to version
history VH19, and the other with binding name "b" to version history
VH24, /x MUST have two version-controlled bindings, one named "a" to
a version-controlled resource for history VH19, and the other named
"b" to a version-controlled resource for history VH24. The version-
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controlled resource /x/a currently has V4 of VH19 as its
DAV:checked-in version, while /x/b has V8 of VH24 as its
DAV:checked-in version.
VH19
+---------+
| +---+ |
| | |V4 |
| +---+ |
| | |
| | |
| +---+ |
| | |V5 |
VH14 | +---+ |
+---------+ | | |
| +---+ | | | |
a +---+ | | |V1 | | +---+ |
---->| |checked-in=V4 | +---+ | a | | |V6 |
/ +---+ | | ------>| +---+ |
/ | | / | +---------+
+---+ | +---+ |
/x | |checked-in=V2 | | |V2 |
+---+ | +---+ | VH24
\ | | \ | b +---------+
\ b +---+ | | ------>| +---+ |
---->| |checked-in=V8 | +---+ | | | |V7 |
+---+ | | |V3 | | +---+ |
| +---+ | | | |
+---------+ | | |
| +---+ |
| | |V8 |
| +---+ |
| | |
| | |
| +---+ |
| | |V9 |
| +---+ |
+---------+
For any request (e.g., DELETE, MOVE, COPY) that modifies a version-
controlled binding of a checked-in version-controlled collection, the
request MUST fail unless the version-controlled collection has a
DAV:auto-version property that will automatically check out the
version-controlled collection when it is modified.
Although a collection version only records the version-controlled
bindings of a collection, a version-controlled collection MAY contain
both version-controlled and non-version-controlled bindings. Non-
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version-controlled bindings are not under version control, and
therefore can be added or deleted without checking out the version-
controlled collection.
Note that a collection version captures only a defined subset of the
state of a collection. In particular, a version of a collection
captures its dead properties and its bindings to version-controlled
resources, but not its live properties or bindings to non-version-
controlled resources.
When a server supports the working-resource feature, a client can
check out a collection version to create a working collection.
Unlike a version-controlled collection, which contains bindings to
version-controlled resources and non-version-controlled resources, a
working collection contains bindings to version history resources and
non-version-controlled resources. In particular, a working
collection is initialized to contain bindings to the version history
resources specified by the DAV:version-controlled-binding-set of the
checked out collection version. The members of a working collection
can then be deleted or moved to another working collection. Non-
version-controlled resources can be added to a working collection
with methods such as PUT, COPY, and MKCOL. When a working collection
is checked in, a VERSION-CONTROL request is automatically applied to
every non-version-controlled member of the working collection, and
each non-version-controlled member is replaced by its newly created
version history. The DAV:version-controlled-binding-set of the new
version resulting from checking in a working collection contains the
binding name and version history URL for each member of the working
collection.
14.1 Version-Controlled Collection Properties
A version-controlled collection has all the properties of a
collection and of a version-controlled resource. In addition, the
version-controlled-collection feature introduces the following
REQUIRED property for a version-controlled collection.
14.1.1 DAV:eclipsed-set (computed)
This property identifies the non-version-controlled internal members
of the collection that currently are eclipsing a version-controlled
internal member of the collection.
!ELEMENT eclipsed-set (binding-name*)>
<!ELEMENT binding-name (#PCDATA)>
PCDATA value: URL segment
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An UPDATE or MERGE request can give a version-controlled collection a
version-controlled internal member that has the same name as an
existing non-version-controlled internal member. In this case, the
non-version-controlled internal member takes precedence and is said
to "eclipse" the new versioned-controlled internal member. If the
non-version-controlled internal member is removed (e.g., by a DELETE
or MOVE), the version-controlled internal member is exposed.
14.2 Collection Version Properties
A collection version has all the properties of a version. In
addition, the version-controlled-collection feature introduces the
following REQUIRED property for a collection version.
14.2.1 DAV:version-controlled-binding-set (protected)
This property captures the name and version-history of each version-
controlled internal member of a collection.
<!ELEMENT version-controlled-binding-set
(version-controlled-binding*)>
<!ELEMENT version-controlled-binding
(binding-name, version-history)>
<!ELEMENT binding-name (#PCDATA)>
PCDATA value: URL segment
<!ELEMENT version-history (href)>
14.3 Additional OPTIONS Semantics
If the server supports the version-controlled-collection feature, it
MUST include "version-controlled-collection" as a field in the DAV
response header from an OPTIONS request on any resource that supports
any versioning properties, reports, or methods.
14.4 Additional DELETE Semantics
Additional Preconditions:
(DAV:cannot-modify-checked-in-parent): If the request-URL
identifies a version-controlled resource, the DELETE MUST fail
when the collection containing the version-controlled resource is
a checked-in version-controlled collection, unless DAV:auto-
version semantics will automatically check out the version-
controlled collection.
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14.5 Additional MKCOL Semantics
Additional Preconditions:
If the request creates a new resource that is automatically placed
under version control, all preconditions for VERSION-CONTROL apply
to the request.
Additional Postconditions:
If the new collection is automatically put under version control,
all postconditions for VERSION-CONTROL apply to the request.
14.6 Additional COPY Semantics
Additional Preconditions:
(DAV:cannot-copy-collection-version): If the source of the request
is a collection version, the request MUST fail.
14.7 Additional MOVE Semantics
Additional Preconditions:
(DAV:cannot-modify-checked-in-parent): If the source of the
request is a version-controlled resource, the request MUST fail
when the collection containing the source is a checked-in
version-controlled collection, unless DAV:auto-version semantics
will automatically check out that version-controlled collection.
(DAV:cannot-modify-destination-checked-in-parent): If the source
of the request is a version-controlled resource, the request MUST
fail when the collection containing the destination is a checked-
in version-controlled collection, unless DAV:auto-version
semantics will automatically check out that version-controlled
collection.
14.8 Additional VERSION-CONTROL Semantics
Additional Preconditions:
(DAV:cannot-modify-checked-in-parent): If the parent of the
request-URL is a checked-in version-controlled collection, the
request MUST fail unless DAV:auto-version semantics will
automatically check out that version-controlled collection.
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Additional Postconditions:
(DAV:new-version-controlled-collection): If the request body
identified a collection version, the collection at the request-URL
MUST contain a version-controlled internal member for each
DAV:version-controlled-binding specified in the DAV:version-
controlled-binding-set of the collection version, where the name
and DAV:version-history of the internal member MUST be the
DAV:binding-name and the DAV:version-history specified by the
DAV:version-controlled-binding. If the internal member is a
member of a workspace, and there is another member of the
workspace for the same version history, those two members MUST
identify the same version-controlled resource; otherwise, a
VERSION-CONTROL request with a server selected version of the
version history MUST have been applied to the URL for that
internal member.
14.9 Additional CHECKOUT Semantics
Additional Postconditions:
(DAV:initialize-version-history-bindings): If the request has been
applied to a collection version, the new working collection MUST
be initialized to contain a binding to each of the history
resources identified in the DAV:version-controlled-binding-set of
that collection version.
14.10 Additional CHECKIN Semantics
Additional Postconditions:
(DAV:initialize-version-controlled-bindings): If the request-URL
identified a version-controlled collection, then the DAV:version-
controlled-binding-set of the new collection version MUST contain
a DAV:version-controlled-binding that identifies the binding name
and version history for each version-controlled binding of the
version- controlled collection.
(DAV:version-control-working-collection-members): If the request-
URL identified a working collection, a VERSION-CONTROL request
MUST have been automatically applied to every non-version-
controlled member of the working collection, and each non-
version-controlled member MUST have been replaced by its newly
created version history. If a working collection member was a
non-version-controlled collection, every member of the non-
version-controlled collection MUST have been placed under version
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control before the non-version-controlled collection was placed
under version control. The DAV:version-controlled-binding-set of
the new collection version MUST contain a DAV:version-controlled-
binding that identifies the binding name and the version history
URL for each member of the working collection.
14.11 Additional UPDATE and MERGE Semantics
Additional Postconditions:
(DAV:update-version-controlled-collection-members): If the request
modified the DAV:checked-in version of a version-controlled
collection, then the version-controlled members of that version-
controlled collection MUST have been updated. In particular:
- A version-controlled internal member MUST have been deleted if
its version history is not identified by the DAV:version-
controlled-binding-set of the new DAV:checked-in version.
- A version-controlled internal member for a given version
history MUST have been renamed if its binding name differs from
the DAV:binding-name for that version history in the
DAV:version-controlled-binding-set of the new DAV:checked-in
version.
- A new version-controlled internal member MUST have been created
when a version history is identified by the DAV:version-
controlled-binding-set of the DAV:checked-in version, but there
was no member of the version-controlled collection for that
version history. If a new version-controlled member is in a
workspace that already has a version-controlled resource for
that version history, then the new version-controlled member
MUST be just a binding (i.e., another name for) that existing
version-controlled resource. Otherwise, the content and dead
properties of the new version-controlled member MUST have been
initialized to be those of the version specified for that
version history by the request. If no version is specified for
that version history by the request, the version selected is
server defined.
15 Internationalization Considerations
This specification has been designed to be compliant with the IETF
Policy on Character Sets and Languages [RFC 2277]. Specifically,
where human-readable strings exist in the protocol, either their
charset is explicitly stated, or XML mechanisms are used to specify
the charset used. Additionally, these human-readable strings all
have the ability to express the natural language of the string.
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Most of the human-readable strings in this protocol appear in
properties, such as DAV:creator-displayname. As defined by RFC 2518,
properties have their values marshaled as XML. XML has explicit
provisions for character set tagging and encoding, and requires that
XML processors read XML elements encoded, at minimum, using the UTF-8
[RFC 2279] encoding of the ISO 10646 multilingual plane. The charset
parameter of the Content-Type header, together with the XML
"encoding" attribute, provide charset identification information for
MIME and XML processors. Proper use of the charset header with XML
is described in RFC 3023. XML also provides a language tagging
capability for specifying the language of the contents of a
particular XML element. XML uses either IANA registered language
tags (see RFC 3066) or ISO 639 language tags in the "xml:lang"
attribute of an XML element to identify the language of its content
and attributes.
DeltaV applications, since they build upon WebDAV, are subject to the
internationalization requirements specified in RFC 2518, Section 16.
In brief, these requirements mandate the use of XML character set
tagging, character set encoding, and language tagging capabilities.
Additionally, they strongly recommend reading RFC 3023 for
instruction on the use of MIME media types for XML transport and the
use of the charset header.
Within this specification, a label is a human-readable string that is
marshaled in the Label header and as XML in request entity bodies.
When used in the Label header, the value of the label is URL-escaped
and encoded using UTF-8.
16 Security Considerations
All of the security considerations of WebDAV discussed in RFC 2518,
Section 17 also apply to WebDAV versioning. Some aspects of the
versioning protocol help address security risks introduced by WebDAV,
but other aspects can increase these security risks. These issues
are detailed below.
16.1 Auditing and Traceability
WebDAV increases the ease with which a remote client can modify
resources on a web site, but this also increases the risk of
important information being overwritten and lost, either through user
error or user maliciousness. The use of WebDAV versioning can help
address this problem by guaranteeing that previous information is
saved in the form of immutable versions, and therefore is easily
available for retrieval or restoration. In addition, the version
history provides a log of when changes were made, and by whom. When
requests are appropriately authenticated, the history mechanism
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provides a clear audit trail for changes to web resources. This can
often significantly improve the ability to identify the source of the
security problem, and thereby help guard against it in the future.
16.2 Increased Need for Access Control
WebDAV versioning provides a variety of links between related pieces
of information. This can increase the risk that authentication or
authorization errors allow a client to locate sensitive information.
For example, if version history is not appropriately protected by
access control, a client can use the version history of a public
resource to identify later versions of that resource that the user
intended to keep private. This increases the need for reliable
authentication and accurate authorization.
A WebDAV versioning client should be designed to handle a mixture of
200 (OK) and 403 (Forbidden) responses on attempts to access the
properties and reports that are supported by a resource. For
example, a particular user may be authorized to access the content
and dead properties of a version-controlled resource, but not be
authorized to access the DAV:checked-in, DAV:checked-out, or
DAV:version-history properties of that resource.
16.3 Security Through Obscurity
While it is acknowledged that "obscurity" is not an effective means
of security, it is often a good technique to keep honest people
honest. Within this protocol, version URLs, version history URLs,
and working resource URLs are generated by the server and can be
properly obfuscated so as not to draw attention to them. For
example, a version of "http://foobar.com/reviews/salaries.html" might
be assigned a URL such as "http://foobar.com/repo/4934943".
16.4 Denial of Service
The auto-versioning mechanism provided by WebDAV can result in a
large number of resources being created on the server, since each
update to a resource could potentially result in the creation of a
new version resource. This increases the risk of a denial of service
attack that exhausts the storage capability of a server. This risk
is especially significant because it can be an unintentional result
of something like an aggressive auto-save feature provided by an
editing client. A server can decrease this risk by using delta
storage techniques to minimize the cost of additional versions, and
by limiting auto-versioning to a locking client, and thereby
decreasing the number of inadvertent version creations.
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17 IANA Considerations
This document uses the namespace defined by RFC 2518 for XML
elements. All other IANA considerations from RFC 2518 are also
applicable to WebDAV Versioning.
18 Intellectual Property
The following notice is copied from RFC 2026, Section 10.4, and
describes the position of the IETF concerning intellectual property
claims made against this document.
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use other technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
procedures of the IETF with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementers or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
19 Acknowledgements
This protocol is the collaborative product of the authors and the
rest of the DeltaV design team: Boris Bokowski, Bruce Cragun
(Novell), Jim Doubek (Macromedia), David Durand (INSO), Lisa
Dusseault (Xythos), Chuck Fay (FileNet), Yaron Goland, Mark Hale
(Interwoven), Henry Harbury (Merant), James Hunt, Jeff McAffer (OTI),
Peter Raymond (Merant), Juergen Reuter, Edgar Schwarz (Marconi), Eric
Sedlar (Oracle), Bradley Sergeant, Greg Stein, and John Vasta
(Rational). We would like to acknowledge the foundation laid for us
by the authors of the WebDAV and HTTP protocols upon which this
protocol is layered, and the invaluable feedback from the WebDAV and
DeltaV working groups.
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20 References
[ISO639] ISO, "Code for the representation of names of languages",
ISO 639:1988, 1998.
[RFC 2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 2277] Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, January 1998.
[RFC 2279] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 2279, January 1998.
[RFC 2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
[RFC 2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S. and D.
Jensen, "HTTP Extensions for Distributed Authoring -
WEBDAV", RFC 2518, February 1999.
[RFC 2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,
L., Leach, P. and T.Berners-Lee, "Hypertext Transfer
Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC 3023] Murata, M., St.Laurent, S. and D. Kohn, "XML Media Types",
RFC 3023, January 2001.
[RFC 3066] Alvestrand, H., "Tags for the Identification of Languages",
BCP 47, RFC 3066, January 2001.
Clemm, et al. Standards Track PAGE 110
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Appendix A - Resource Classification
This document introduces several different kinds of versioning
resources, such as version-controlled resources, versions, checked-
out resources, and version history resources. As clients discover
resources on a server, they may find it useful to classify those
resources (for example, to make UI decisions on choice of icon and
menu options).
Clients should classify a resource by examining the values of the
DAV:supported-method-set (see Section 3.1.3) and DAV:supported-live-
property-set (see Section 3.1.4) properties of that resource.
The following list shows the supported live properties and methods
for each kind of versioning resource. Where an optional feature
introduces a new kind of versioning resource, that feature is noted
in parentheses following the name of that kind of versioning
resource. If a live property or method is optional for a kind of
versioning resource, the feature that introduces that live property
or method is noted in parentheses following the live property or
method name.
A.1 DeltaV-Compliant Unmapped URL (a URL that identifies no resource)
Supported methods:
- PUT [RFC 2616]
- MKCOL [RFC 2518]
- MKACTIVITY (activity)
- VERSION-CONTROL (workspace)
- MKWORKSPACE (workspace)
A.2 DeltaV-Compliant Resource
Supported live properties:
- DAV:comment
- DAV:creator-displayname
- DAV:supported-method-set
- DAV:supported-live-property-set
- DAV:supported-report-set
- all properties defined in WebDAV [RFC 2518].
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Supported methods:
- REPORT
- all methods defined in WebDAV [RFC 2518]
- all methods defined in HTTP/1.1 [RFC 2616].
A.3 DeltaV-Compliant Collection
Supported live properties:
- all DeltaV-compliant resource properties.
Supported methods:
- BASELINE-CONTROL (baseline)
- all DeltaV-compliant resource methods.
A.4 Versionable Resource
Supported live properties:
- DAV:workspace (workspace)
- DAV:version-controlled-configuration (baseline)
- all DeltaV-compliant resource properties.
Supported methods:
- VERSION-CONTROL
- all DeltaV-compliant resource methods.
A.5 Version-Controlled Resource
Supported live properties:
- DAV:auto-version
- DAV:version-history (version-history)
- DAV:workspace (workspace)
- DAV:version-controlled-configuration (baseline)
- all DeltaV-compliant resource properties.
Supported methods:
- VERSION-CONTROL
- MERGE (merge)
- all DeltaV-compliant resource methods.
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A.6 Version
Supported live properties:
- DAV:predecessor-set
- DAV:successor-set
- DAV:checkout-set
- DAV:version-name
- DAV:checkout-fork (in-place-checkout or working resource)
- DAV:checkin-fork (in-place-checkout or working resource)
- DAV:version-history (version-history)
- DAV:label-name-set (label)
- DAV:activity-set (activity)
- all DeltaV-compliant resource properties.
Supported methods:
- LABEL (label)
- CHECKOUT (working-resource)
- all DeltaV-compliant resource methods.
A.7 Checked-In Version-Controlled Resource
Supported live properties:
- DAV:checked-in
- all version-controlled resource properties.
Supported methods:
- CHECKOUT (checkout-in-place)
- UPDATE (update)
- all version-controlled resource methods.
A.8 Checked-Out Resource
Supported live properties:
- DAV:checked-out
- DAV:predecessor-set
- DAV:checkout-fork (in-place-checkout or working resource)
- DAV:checkin-fork (in-place-checkout or working resource)
- DAV:merge-set (merge)
- DAV:auto-merge-set (merge)
- DAV:unreserved (activity)
- DAV:activity-set (activity)
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Supported methods:
- CHECKIN (checkout-in-place or working-resource)
- all DeltaV-compliant resource methods.
A.9 Checked-Out Version-Controlled Resource (checkout-in-place)
Supported live properties:
- all version-controlled resource properties.
- all checked-out resource properties.
Supported methods:
- UNCHECKOUT
- all version-controlled resource methods.
- all checked-out resource methods.
A.10 Working Resource (working-resource)
Supported live properties:
- all DeltaV-compliant resource properties
- all checked-out resource properties
- DAV:auto-update.
Supported methods:
- all checked-out resource methods.
A.11 Version History (version-history)
Supported live properties:
- DAV:version-set
- DAV:root-version
- all DeltaV-compliant resource properties.
Supported methods:
- all DeltaV-compliant resource methods.
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A.12 Workspace (workspace)
Supported live properties:
- DAV:workspace-checkout-set
- DAV:baseline-controlled-collection-set (baseline)
- DAV:current-activity-set (activity)
- all DeltaV-compliant collection properties.
Supported methods:
- all DeltaV-compliant collection methods.
A.13 Activity (activity)
Supported live properties:
- DAV:activity-version-set
- DAV:activity-checkout-set
- DAV:subactivity-set
- DAV:current-workspace-set
- all DeltaV-compliant resource properties.
Supported methods:
- all DeltaV-compliant resource methods.
A.14 Version-Controlled Collection (version-controlled-collection)
Supported live properties:
- DAV:eclipsed-set
- all version-controlled resource properties.
Supported methods:
- all version-controlled resource methods.
A.15 Collection Version (version-controlled-collection)
Supported live properties:
- DAV:version-controlled-binding-set
- all version properties.
Supported methods:
- all version methods.
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A.16 Version-Controlled Configuration (baseline)
Supported live properties:
- DAV:baseline-controlled-collection
- all version-controlled resource properties.
Supported methods:
- all version-controlled resource methods.
A.17 Baseline (baseline)
Supported live properties:
- DAV:baseline-collection
- DAV:subbaseline-set
- all version properties.
Supported methods:
- all version methods.
A.18 Checked-Out Version-Controlled Configuration (baseline)
Supported live properties:
- DAV:subbaseline-set
- all version-controlled configuration properties.
Supported methods:
- all version-controlled configuration methods.
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Authors' Addresses
Geoffrey Clemm
Rational Software
20 Maguire Road, Lexington, MA 02421
EMail: geoffrey.clemm@rational.com
Jim Amsden
IBM
3039 Cornwallis, Research Triangle Park, NC 27709
EMail: jamsden@us.ibm.com
Tim Ellison
IBM
Hursley Park, Winchester, UK S021 2JN
EMail: tim_ellison@uk.ibm.com
Christopher Kaler
Microsoft
One Microsoft Way, Redmond, WA 90852
EMail: ckaler@microsoft.com
Jim Whitehead
UC Santa Cruz, Dept. of Computer Science
1156 High Street, Santa Cruz, CA 95064
EMail: ejw@cse.ucsc.edu
Clemm, et al. Standards Track PAGE 117
RFC 3253 Versioning Extensions to WebDAV March 2002
Full Copyright Statement
Copyright © The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
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included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
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This document and the information contained herein is provided on an
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Clemm, et al. Standards Track PAGE 118
Versioning Extensions to WebDAV (Web Distributed Authoring and Versioning)
RFC TOTAL SIZE: 245514 bytes
PUBLICATION DATE: Monday, March 4th, 2002
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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