INTERNET-DRAFT Geoffrey Clemm, Rational Software
draft-ietf-deltav-versioning-01.txt Chris Kaler, Microsoft
Expires April 22, 2000 October 22, 1999
Versioning Extensions to WebDAV
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet- Drafts as reference material
or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
This document specifies a set of methods, headers, and resource-types
that define the WebDAV Versioning extensions to the HTTP/1.1 protocol.
WebDAV Versioning will minimize the complexity of clients so as to
facilitate widespread deployment of applications capable of utilizing
the WebDAV Versioning services. WebDAV Versioning includes:
- Basic versioning with automatic versioning for versioning-unaware
clients,
- Activity and configuration management ,
- URL namespace versioning.
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Table of Contents
VERSIONING EXTENSIONS TO WEBDAV...........................1
STATUS OF THIS MEMO.......................................1
ABSTRACT..................................................1
TABLE OF CONTENTS.........................................2
1 INTRODUCTION...........................................5
1.1 Relationship to DAV.................................5
1.2 Terms...............................................5
1.3 Notational Conventions.............................11
2 WEBDAV VERSIONING SEMANTICS...........................11
2.1 Creating Versioned Resources.......................11
2.2 Modifying a Versioned Resource.....................11
2.3 Naming Revisions: Revision Ids and Revision Labels.12
2.4 Revision Selection and Workspaces..................13
2.5 Parallel Development and Activities <Activity>.....13
2.6 Configurations <Activity>..........................14
2.7 Versioned Collections <Versioned-Collection>.......14
2.8 Repositories <Versioned-Collection>................15
3 VERSIONING PROPERTIES BY RESOURCE TYPE................15
3.1 Property Characteristics...........................15
3.1.1 Writeable/Readonly Properties....................15
3.1.2 Mutable Properties...............................15
3.1.3 Property Resources...............................15
3.2 Common Property Values.............................16
3.2.1 boolean Syntax...................................16
3.2.2 segment Syntax...................................16
3.2.3 date-time Syntax.................................16
3.2.4 href XML Element.................................16
3.3 Resource Properties................................16
3.3.1 DAV:author.......................................16
3.3.2 DAV:comment......................................16
3.4 Versioned Resource Properties......................16
3.4.1 DAV:versioned-resource-id (readonly).............17
3.4.2 DAV:default-workspace (readonly, resource).......17
3.4.3 DAV:revisions (readonly, collection).............17
3.4.4 DAV:labeled-revisions (collection)...............17
3.4.5 DAV:single-checkout..............................17
3.4.6 DAV:auto-version.................................17
3.4.7 DAV:baselines (readonly, collection)
<Versioned-Collection>...........................18
3.4.8 DAV:repository (readonly, resource)
<Versioned-Collection>...........................18
3.5 Revision Properties................................18
3.5.1 DAV:revision-id (readonly).......................18
3.5.2 DAV:predecessor (readonly, resource).............18
3.5.3 DAV:successors (readonly, mutable, collection)...19
3.5.4 DAV:labels (readonly, mutable)...................19
3.5.5 DAV:checkin-date (readonly)......................19
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3.5.6 DAV:workspaces (readonly, collection)............19
3.5.7 DAV:versioned-resource (readonly, resource)......19
3.5.8 DAV:activity (readonly, resource) <Activity>.....19
3.5.9 DAV:merge-predecessors (mutable, collection)
<Activity>.......................................20
3.5.10DAV:merge-successors (mutable, collection)
<Activity>.......................................20
3.6 Working Resource Properties........................20
3.6.1 DAV:predecessor (read-only, resource)............20
3.6.2 DAV:checkin-policy...............................20
3.6.3 DAV:merge-predecessors (collection) <Activity>...21
3.6.4 DAV:activity (readonly, resource) <Activity>.....21
3.7 Workspace Properties...............................21
3.7.1 DAV:working-resources (readonly, collection).....21
3.7.2 DAV:revision-selection-rule......................21
3.7.3 DAV:no-checkout..................................23
3.7.4 DAV:current-label................................23
3.7.5 DAV:current-activity (resource) <Activity>.......23
3.8 Activity Properties <Activity>.....................24
3.8.1 DAV:revisions (readonly, collection).............24
3.8.2 DAV:required-activities (collection).............24
3.8.3 DAV:workspaces (readonly, collection)............24
3.9 Baseline Properties <Versioned-Collection>.........24
3.9.1 DAV:baseline-id (readonly).......................24
3.9.2 DAV:predecessor (readonly, resource).............24
3.9.3 DAV:successors (readonly, mutable, collection)...25
3.9.4 DAV:versioned-resource (readonly, resource)......25
3.9.5 DAV:merge-predecessors (mutable, collection).....25
3.9.6 DAV:merge-successors (mutable, collection).......25
3.9.7 DAV:activity (readonly, resource)................25
3.10 Repository Properties <Versioned-Collection>.......25
3.10.1DAV:versioned-resources (readonly, collection)...25
3.10.2DAV:root-versioned-collection (readonly, resource)26
3.10.3DAV:activities (collection)......................26
3.10.4DAV:configurations (collection)..................26
3.10.5DAV:workspaces (collection)......................26
3.10.6DAV:default-workspace (resource).................26
4 EXISTING METHODS......................................26
4.1 GET................................................27
4.2 PUT................................................27
4.3 PROPFIND...........................................27
4.4 PROPPATCH..........................................27
4.5 COPY...............................................28
4.6 DELETE.............................................28
4.7 BIND...............................................28
4.8 MOVE...............................................28
4.9 LOCK...............................................28
4.10 UNLOCK.............................................29
4.11 OPTIONS............................................29
5 NEW METHODS...........................................29
5.1 MKRESOURCE.........................................29
5.1.1 New DAV:resourcetype Values......................30
5.1.2 Example - MKRESOURCE.............................30
5.2 REPORT.............................................31
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5.2.1 DAV:report-request...............................32
5.2.2 DAV:report-response..............................32
5.3 Available REPORT...................................32
5.3.1 DAV:available-report-request.....................32
5.3.2 DAV:available-report-response....................32
5.3.3 Example - Available REPORT.......................32
5.4 Conflict REPORT....................................33
5.4.1 DAV:conflict-report-request......................33
5.4.2 DAV:conflict-report-response.....................33
5.4.3 DAV:conflict.....................................34
5.4.4 DAV:common-ancestor..............................34
5.4.5 DAV:contributor..................................34
5.4.6 Example - Conflict REPORT........................34
5.5 Compare REPORT.....................................35
5.5.1 DAV:compare-request..............................35
5.5.2 DAV:compare-response.............................35
5.5.3 DAV:added........................................35
5.5.4 DAV:deleted......................................36
5.5.5 DAV:changed......................................36
5.5.6 Example - Compare REPORT.........................36
6 NEW VERSIONING METHODS................................37
6.1 CHECKOUT...........................................37
6.1.1 Example - CHECKOUT...............................38
6.2 CHECKIN............................................39
6.2.1 Example - CHECKIN................................40
7 NEW VERSIONING HEADERS................................41
7.1 Target-Selector....................................41
8 INTERNATIONALIZATION CONSIDERATIONS...................42
9 SECURITY CONSIDERATIONS...............................42
10 SCALABILITY..........................................42
11 AUTHENTICATION.......................................42
12 IANA CONSIDERATIONS..................................42
13 INTELLECTUAL PROPERTY................................42
14 ACKNOWLEDGEMENTS.....................................43
15 INDEX................................................43
16 REFERENCES...........................................43
17 AUTHORS' ADDRESSES...................................43
18 OPEN ISSUES..........................................44
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1 INTRODUCTION
This document defines WebDAV Versioning extensions, an application
of HTTP/1.1 for handling resource versioning in a WebDAV
environment. [Goals] describes the motivation and requirements for
WebDAV Versioning.
WebDAV Versioning will minimize the complexity of clients so as to
facilitate widespread deployment of applications capable of
utilizing the WebDAV services. WebDAV Versioning defines three
levels of versioning functionality for versioning-aware clients:
- Basic versioning with automatic versioning for versioning-unaware
clients,
- Activity and configuration management ,
- URL namespace versioning.
1.1 Relationship to DAV
To maximize interoperability and the use of existing protocol
functionality, versioning support is designed as extensions to the
WebDAV [RFC2518] and Binding protocols [Binding]. In particular,
WebDAV Versioning relies on the resource and property model defined
by [RFC2518] and the binding model defined by [Binding]. The
versioning protocol is designed so that WebDAV LOCK/UNLOCK requests
can be mapped into versioning CHECKOUT/CHECKIN requests. This
provides interoperability between locking clients and versioning
servers.
This protocol defines three levels of versioning support: Core,
Activity, and Versioned-Collection support. Core support provides
versioning of largely independent resources. It allows authors to
concurrently create and access distinct revisions of a resource.
Activity support extends Core support with logical change tracking
and configuration management. Versioned-Collection support extends
Activity support with the ability to version the URL namespace.
Throughout this specification, the notations <Activity> and
<Versioned-Collection> indicate concepts that are introduced by
Activity and Versioned-Collection, respectively. The level of
versioning support provided by a server can be discovered via an
OPTIONS request.
1.2 Terms
This draft uses the terms defined in [RFC2068] and [RFC2518]. In
addition, the following terms are defined:
Versionable Resource
A versionable resource is a resource that can be placed under
version control.
Versioned Resource
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A versioned resource is a resource that is under version control.
A versioned resource tracks the history of its significant states,
called revisions of that versioned resource. To update a resource
under version control, it must be checked out and then subsequently
checked in.
Revision
A revision of a versioned resource is created by a CHECKIN
operation, and captures the current state of the versioned
resource.
Mutable Property
A mutable property is a property of a revision that can be changed
without checking out that revision.
Revision Name
A revision name is a name that can be used to identify a single
revision of a versioned resource. There are two types of revision
names: revision identifiers and revision labels.
Revision Identifier
A revision identifier (or revision ID) is a revision name that is
assigned by the server when the revision is created and cannot be
changed to refer to a different revision.
Revision Label
A revision label is a revision name that is assigned by a client
and may later be changed to refer to a different revision. The same
label may be assigned to many different versioned resources.
Initial Revision
An initial revision is the first revision of a versioned resource.
Predecessor, Successor
A predecessor of a revision is the previous revision that was
checked out to create the revision. A successor of a revision is a
revision whose predecessor is that revision. Each revision has a
single predecessor (except for the initial revision which has no
predecessor) and zero or more successors.
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Line Of Descent
A line of descent to a specified revision is a sequence of
revisions connected by successor relationships from the initial
revision to that revision.
The following diagram illustrates several of the previous
definitions.
Versioned ------> Foo.htm
Resource
+----+ \
Label ----> "stable" | V1 | | |
\ +----+ | |
\ | | |
\ v | |
\ +----+ | Line |
-> "beta1" | V2 | | of |
+----+ | Descent |
/ | | to |
v v | V6 |
+----+ +----+ | |
Revision Id --> | V3 | | V4 | | | History
+----+ +----+ | | of
^ | | | | Foo.htm
Predecessor | v v | |
| +----+ +----+ v |
| V5 | | V6 | |
+----+ +----+ |
| | |
Successor | v |
v +----+ |
| V7 | |
+----+ /
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Checkout/Checkin Model
The checkout/checkin model is the process by which updates are made
to a versioned resource. A versioned resource is checked out to
create an editable working resource. The working resource is
updated or augmented as desired, and then checked in to make it
part of the revision history of the versioned resource.
The following diagram illustrates the checkout/checkin process.
===CHECKOUT==> ===CHECKIN==>
Foo.htm | Foo.htm | Foo.htm
| |
+----+ | +----+ | +----+
| V1 | | | V1 | | | V1 |
+----+ | +----+ | +----+
| | | | |
v | v | v
+----+ | +----+ | +----+
| V2 | | | V2 | | | V2 |
+----+ | +----+ | +----+
| | | |
| v | v
| +----+ | +----+
| | WR | | | V3 |
| +----+ | +----+
Working Resource
A working resource is an editable resource created by checking out
a revision of a versioned resource.
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Workspace
A workspace is a resource that is used to identify working
resources. A workspace can also contain a revision selection rule
that specifies what revision of an arbitrary versioned resource
should be accessed when the resource is referenced in the context
of that workspace. A revision selection rule provides revision
selection based on criteria such as revision name, latest in an
activity, and membership in a configuration.
A workspace that does not contain a revision selection rule (and
therefore can only be used to identify working resources) is called
a basic workspace. A workspace that contains a revision selection
rule (and therefore can be used to specify revision selection) is
called an extended workspace.
The following diagram illustrates an extended workspace.
Foo.htm Bar.htm Bing.htm
+----+ +----+
| V1 | | V1 |
+----+ +----+
| |
| |
+-----------------|------------|------------------+
| v v |
| +----+ +----+ +----+ |
| | V1 | | V2 | | WR | Workspace X |
| +----+ +----+ +----+ |
| | |
+-----------------|-------------------------------+
|
v
+----+
| V3 |
+----+
Default Workspace
A server MUST provide a default workspace that is used to perform
version selection for versioning-unaware clients. The revision
selection rule of the default workspace MAY be a modifiable by a
client.
Target
Whenever a server encounters a versioned resource while it is
processing an HTTP request, it is required to act on the "target"
of the versioned resource, rather than the versioned resource
itself. Target selection is performed based on the value of the
Target-Selector header of the request. Commonly, the Target-
Selector header specifies a workspace that selects a working
resource or revision of the versioned resource to be the target. A
special Target-Selector value can be specified to select the
versioned resource itself to be the target. If no Target-Selector
header is specified, the default workspace of the versioned
resource is used to determine target selection.
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Default Target
The "default target" of a versioned resource is the target selected
by the default workspace.
Activity <Activity>
An activity is a resource that selects a set of revisions that
correspond to some unit of work or conceptual change. An activity
can contain revisions of multiple versioned resources, and multiple
revisions of the same versioned resource. If an activity contains
multiple revisions of the same versioned resource, all of those
revisions must be on a single line of descent to one of those
revisions, and this revision is called the latest revision selected
by that activity for that versioned resource.
The following diagram illustrates activities. Revision V3 is the
latest revision of Foo.htm selected by activity 2, and revision V7
is the latest revision of Bar.htm selected by activity 2.
Foo.htm | Bar.htm
|
+----+ | +----+
| V1 | | | V5 |
+----+ | +----+
| Activity | | Activity
v 1 | v 2
+----+ | +----+
| V2 | | | V6 |
+----+ | +----+
| Activity | | Activity
v 2 | v 2
+----+ | +----+
| V3 | | | V7 |
+----+ | +----+
| | Activity
| v 3
| +----+
| | V8 |
| +----+
Merge Predecessor, Merge Successor <Activity>
A merge predecessor of a revision is a revision that has been
merged into this revision. A merge successor of a revision is a
revision into which that revision has been merged. A revision can
have zero or more merge predecessors and zero or more merge
successors.
Conflict Report <Activity>
A conflict report lists all versioned resources for which the
revision selection rule of a workspace selects multiple revisions
on different lines of descent. A conflict is resolved by checking
out one of the selected revisions, modifying the resulting working
resource so that it represents the logical merge of all selected
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revisions, and then indicating these merges by adding these
revisions as merge predecessors of the working resource. Checking
in this working resource creates a new revision that resolves the
conflict.
Configuration <Activity>
A configuration is a type of collection that contains a set of
revisions, with a most one revision from any versioned resource.
Unlike a workspace, which can select both working resources and
revisions, a configuration can only select revisions. Also, while
the revision selected by a workspace for a versioned resource can
change as a result of a change to the versioned resource (such as
adding a label), the revision selected by a configuration can
change only by explicitly modifying the configuration. Unlike an
activity, a configuration can contain at most one revision of a
given versioned resource. Unlike both a workspace and an activity,
a configuration can be versioned.
The following diagram illustrates a configuration.
Foo.htm Bar.htm Bing.htm
+----+
| V1 |
+----+
|
|
+-----------------|-------------------------------+
| | |
| +----+ +----+ +----+ Configuration |
| | V1 | | V2 | | V1 | V1.1 |
| +----+ +----+ +----+ |
| | | |
+-----------------|------------|------------------+
| |
v v
+----+ +----+
| V3 | | V2 |
+----+ +----+
Versioned Collection <Versioned-Collection>
A versioned collection is a type of versioned resource that results
from placing a collection under version control. The members of a
versioned collection revision MUST be versioned resources. The
working resource that results from checking out a versioned
collection is called a working collection.
Baseline <Versioned-Collection>
A baseline is a "deep revision" of a versioned collection, where a
deep revision captures not only the revision of the versioned
collection, but also the revision of every members of that
versioned collection selected by that workspace at that moment.
More formally, a baseline contains a revision of the versioned
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collection and a revision or baseline of every member of every
versioned collection revision in that baseline.
Like a configuration, a baseline selects a particular revision for
each of a set of versioned resources. Unlike a configuration, a
baseline cannot be modified once it has been created, and may only
contain exactly those revisions needed to form a deep revision of a
particular versioned collection.
Repository <Versioned-Collection>
A repository is a type of resource that contains related versioned
resources, activities, and configurations. A repository provides a
stable namespace for versioning metadata resources, and provides
versioning unaware clients access to the versioning metadata.
1.3 Notational Conventions
The augmented BNF used by this document to describe protocol
elements is exactly the same as the one described in Section 2.1 of
[RFC2068]. Because this augmented BNF uses the basic production
rules provided in Section 2.2 of [RFC2068], those rules apply to
this document as well.
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 [RFC2119].
2 WEBDAV VERSIONING SEMANTICS
2.1 Creating Versioned Resources
A resource may or may not be versioned. When a resource is created
in an unversioned collection by a PUT or MKRESOURCE request, it is
created as an unversioned resource. When a resource is created in a
versioned collection by a PUT or MKRESOURCE request, it is created
as a versioned resource. Some unversioned resources can be put
under version control; these are called versionable resources. A
versionable resource can be put under version control with a
CHECKOUT operation, and an initial revision is created that is a
copy of the versionable resource.
2.2 Modifying a Versioned Resource
A versioned resource must be checked out before it can be modified.
Checking out a versioned resource produces a new resource, called a
working resource. A working resource is always identified by the
workspace that contains it. A working resource is a modifiable
copy of the revision, and is identical to an unversioned resource
in all respects other than that it is associated with a particular
revision of a particular versioned resource. It may be edited by
setting its properties or contents any number of times. When the
author is satisfied that the working resource is in a state that
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should be retained in the versioned resource history, the author
checks in the working resource to create a new revision of the
versioned resource. The revision that was checked out is the
predecessor of the new revision.
The use of checkout/checkin and working resources to update a
versioned resource addresses the lost update problem by ensuring
that each author is updating his or her own working resource rather
than a shared resource, and by ensuring that the predecessor of the
updated resource is reliably tracked. Authors can use
checkout/checkin to register intent to modify a versioned resource
similar to the way lock /unlock are used in WebDAV class 2, but the
underlying semantics are very different. With lock/unlock, work is
serialized and avoiding lost updates depends on clients using the
lock/unlock protocol. With checkout/checkin, work can be performed
in parallel, and the server prevents lost updates by retaining all
saved states (revisions) of the resource. Another distinction is
that an update to a locked resource is visible to all clients,
while an update to a checked out resource is only visible to other
clients after that update is checked in.
A server MAY support mutable revisions. Normally, a revision cannot
be changed and provides a stable environment for history
management, change recovery, merging, and configuration management.
A mutable revision is more suitable for situations where versioning
is treated more informally, and it is not necessary or desirable to
maintain strict version histories, or to guarantee the possibility
of backtracking to a previous saved state. If mutable revisions are
supported, the author may request that a checkin should overwrite
the revision that was checked out, instead of creating a new
revision. In this case, the previous state captured by that
revision is lost. Servers may choose not to support mutable
revisions.
2.3 Naming Revisions: Revision Ids and Revision Labels
Revision names are used to distinguish a revision of a versioned
resource from other revisions of that versioned resource. A
revision name is either a revision id or any number of revision
labels. A revision of a versioned resource is given a server
assigned revision id when it is created. This revision id acts as a
persistent, immutable identifier distinguishing this revision from
all others of the same versioned resource. The revision id cannot
be changed, assigned to another revision, or reused.
A user may assign revision labels to a revision in order to provide
a more meaningful name for the revision. A given revision label
can be assigned to at most one revision of a given versioned
resource, but may be reassigned to any revision of the versioned
resource at any time.
A revision name does not distinguish revisions from different
resources, since the same revision name can be assigned to a
revision of any versioned resource.
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2.4 Revision Selection and Workspaces
Resources, working resources, and revisions of versioned resources
are all accessed using a URL. When a client accesses a versioned
resource, it is necessary to provide additional information to
specify which working resource or which revision of the versioned
resource should be accessed. Specifying the resource URL and a
revision name can access a specific revision of the versioned
resource. However, this requires the user to add and remember
labels for each revision; it does not provide a way of accessing a
consistent set of revisions captured by an activity or contained in
a configuration; it does not enable non-versioning aware clients to
access revisions; and it does not provide a client with access to a
working resource of a versioned resource.
To address the restrictions inherent in revision-name based
revision selection, the revision selected when a specific revision
name is not specified is resolved through a workspace. A workspace
is a resource whose primary purpose is to identify working
resources. If the workspace contains no working resource for a
given versioned resource, it can also be used to select an
appropriate revision of the versioned resource. This allows
versioned resources and unversioned resources to be accessed
consistently by both versioning-aware and versioning-unaware
clients.
In order to specify revision selection, a workspace contains a
revision selection rule. A revision selection rule can specify
revision names, activities, configurations, or use operators that
combine several of these revision selectors. A revision name
selects a revision with that name. An activity selects the latest
revision that was created in that activity. Configurations select
the revision contained in the configuration. The "or" operator
contains a sequence of rule elements, and applies them in order
until the first match is found. If there is no matching revision,
then a resource-not-found status is returned.
If a request is made and no workspace is specified, a server
determined default workspace is used. This is the workspace used by
all versioning-unaware clients. A server MAY allow modifications to
the revision selection rule of the default workspace.
2.5 Parallel Development and Activities <Activity>
In a locking model, when a resource is locked for modifications by
one author, all other authors are supposed to respect that lock and
not work on a copy of that resource until the lock has been
released. To avoid the work serialization inherent in the locking
model, a versioning model allows multiple authors in different
workspaces to check out the same revision at the same time, work on
their respective working resources in parallel, check in their
respective working resources as soon as their changes are complete,
and then merge the resulting revisions at some later time.
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Although a simple versioning model works well for isolated changes
to independent resources, the required merge process becomes
unmanageable when sequences of inter-related changes are performed
on sets of related resources. To address this merge problem,
resources can be checked out in the context of an activity. An
activity captures the set of revisions that form a set of related
changes an author is making to one or more versioned resources.
Each activity represents a thread of development, where any thread
can be isolated from other threads to provide a stable environment
for parallel work. In case parallel work on isolated activities
results in branches in the underlying versioned resource histories,
the activities can be unified through a merge operation.
2.6 Configurations <Activity>
A workspace selects a volatile set of revisions. Changes to
selected activities or changes to labels may result in the
selection of different revisions. A configuration is a resource
that selects a specific set of revisions. A workspace whose
version selection rule contains a configuration will always select
the same revisions as long as the configuration is not modified and
no checkouts are performed in that workspace.
Configurations are convenient for defining a persistent set of
revisions that relate to each other in some specific way at some
point in time. This can be useful for a variety of purposes such as
publishing consistent versions of resources to deploy an
application, or for recovering a specific state for legal or
maintenance reasons.
2.7 Versioned Collections <Versioned-Collection>
A collection contains a set of named bindings to other resources
that are the members of that collection. For a versioned
collection, the bindings are to versioned resources, not to
particular revisions. To modify the state of a versioned collection
(i.e. add or remove a binding), the versioned collection must be
checked out, just like any other versioned resource. Requests that
modify the state of a collection member, such as checking it out or
checking in a new revision, have no effect on the state of the
collection. Conversely, requests that modify the state of a
versioned collection, such as deleting or adding a binding to a
resource, have no effect on the state of that resource. In
particular, the resource will remain bound in any other revisions
of the collection of which it was a member.
It is often important to capture the entire tree of revisions
selected by a workspace rooted at a given versioned collection.
This "deep revision" of a versioned collection is called a
baseline.
If a URL identifies a sequence of nested versioned collections,
revision selection is performed for each versioned collection in
the sequence, to select the versioned collection revision that will
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be used to map the next segment of the URL to the appropriate
versioned resource.
2.8 Repositories <Versioned-Collection>
When the URL namespace is being versioned by means of versioned
collections, it is important to define a mechanism that provides
stable names for the versioning metadata resources such as
versioned resources, revisions, workspaces, activities,
configurations, and baselines. In order to support stable names, a
repository resource MUST be allocated in an unversioned partition
of the URL namespace. It is possible to version the root
collection of a URL authority, but then the repository for the
versioning metadata must be located at an unversioned partition of
a different URL authority.
3 VERSIONING PROPERTIES BY RESOURCE TYPE
This section defines the new resource types and properties
introduced by WebDAV versioning.
3.1 Property Characteristics
There are several important characteristics of properties that will
be defined for every property introduced by this document.
3.1.1 riteable/Readonly Properties
A writable property can be modified by a client, while a read-only
property can only be modified by the server.
All properties defined in this document are writable unless
explicitly marked as "read-only".
3.1.2 Mutable Properties
A mutable property is a property of a revision that can be changed
without checking out that revision. A property is mutable only if
it is explicitly defined in this document as being mutable.
3.1.3 Property Resources
There are various properties whose contents are represented as an
HTTP resource. Doing so allows a client to use the full set of
HTTP methods to manipulate the contents of that property, rather
than being limited to the functionality provided by PROPFIND and
PROPPATCH. This is particularly valuable for a property value that
is naturally represented as a collection resource. An alternative
approach would be to define new methods and headers for browsing
and updating this information, but the property resource approach
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has the advantage of providing access to users with versioning
unaware clients.
All properties that are property resources are explicitly marked as
"resource". If the property resource is a collection, the property
is marked as "collection".
3.2 Common Property Values
3.2.1 boolean Syntax
Some properties take a Boolean value.
boolean = "F" | "T"
3.2.2 segment Syntax
Some properties take a value suitable for use as a segment of a
URI. The syntax of a segment is defined in section 3.3 of
[RFC2396].
3.2.3 date-time Syntax
Some properties take a date or time value. The syntax of date-time
is defined in section 23.2 of [RFC2518].
3.2.4 href XML Element
The href XML element is defined in section 12.3 of [RFC2518].
3.3 Resource Properties
WebDAV versioning introduces the following additional properties
for a resource:
3.3.1 AV:author
This property is used to track the author of a resource.
<!ELEMENT author (#PCDATA)>
3.3.2 AV:comment
This property is used to track a brief comment about a resource.
<!ELEMENT author (#PCDATA)>
3.4 Versioned Resource Properties
WebDAV versioning introduces the following additional properties
for a versioned resource:
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3.4.1 DAV:versioned-resource-id (readonly)
The DAV:versioned-resource-id is an identifier assigned to a
versioned resource by the server. A versioned resource in a
repository cannot be given a versioned resource id that has been
given to any other versioned resource in that repository, even a
versioned resource that has been deleted.
<!ELEMENT versioned-resource-id (#PCDATA)>
Value: segment
3.4.2 DAV:default-workspace (readonly, resource)
The DAV:default-workspace of a versioned resource specifies the
default workspace used to determine the target of that versioned
resource when no Target-Selector header is specified.
<!ELEMENT default-workspace (href)>
3.4.3 DAV:revisions (readonly, collection)
The DAV:revisions collection of a versioned resource contains all
revisions of that versioned resource, where the name of a revision
in the DAV:revisions collection is its DAV:revision-id.
<!ELEMENT revisions (href)>
3.4.4 DAV:labeled-revisions (collection)
The DAV:labeled-revisions collection is used to add, change, and
remove labels on revisions of a versioned resource. The
DAV:labeled-revisions collection contains a binding for each label
assigned to any revision of that versioned resource, where the
binding name is that label and the binding is to the revision
selected by that label.
A BIND request is used to add or move a revision label. When the
Destination collection of a BIND request is the DAV:labeled-
revisions of a versioned resource, the request-URL of the BIND MUST
identify a revision of that versioned resource. A DELETE request
is used to delete a revision label.
<!ELEMENT labeled-revisions (href)>
3.4.5 DAV:single-checkout
When the DAV:single-checkout property of a versioned-resource is
set, only one working resource can be checked out from that
versioned-resource at any time.
<!ELEMENT single-checkout (#PCDATA)>
Value: boolean
3.4.6 DAV:auto-version
When the DAV:auto-version property of a versioned resource is set,
a request that attempts to modify the state of a revision of that
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versioned resource (such as PUT/PROPPATCH for a basic resource or a
DELETE /MOVE for a collection) is automatically preceded by a
CHECKOUT into the default workspace and automatically followed by a
CHECKIN. This allows a versioning-unaware client to modify a
version-controlled resource. The DAV:auto-version value can take
the same values as the DAV:checkin-policy of a working resource,
and the DAV:checkin-policy of the automatically created working
resource is set to be the DAV:auto-version policy of the revision.
<!ELEMENT auto-version (checkin-policy)>
3.4.7 AV:baselines (readonly, collection) <Versioned-Collection>
The DAV:baselines collection of a versioned collection contains all
baselines of the versioned collection.
<!ELEMENT baselines (href)>
3.4.8 AV:repository (readonly, resource) <Versioned-Collection>
The DAV:repository specifies the repository that contains this
versioned resource.
<!ELEMENT repository (href)>
3.5 Revision Properties
WebDAV versioning introduces the following additional properties
for a revision:
3.5.1 AV:revision-id (readonly)
The DAV:revision-id is an identifier assigned to a revision by the
server. A revision cannot be given a DAV:revision-id that has been
given to any other revision of that versioned resource, even a
revision that has been deleted.
<!ELEMENT revision-id (#PCDATA)>
Value: segment
Since implementations are likely to use revision identifiers in
resource naming schemes, a revision identifier is constrained to be
a legal URL segment. Standard URL encoding techniques should
provide a server with sufficient flexibility in defining revision
identifier formats.
Since a revision identifier can be specified in a Target-Selector
header, the length of a revision-id should be compatible with
common header length constraints.
3.5.2 DAV:predecessor (readonly, resource)
The DAV:predecessor of a revision is the revision that was checked
out to produce a working resource that was checked in to produce
this revision.
<!ELEMENT predecessor (href)>
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3.5.3 DAV:successors (readonly, mutable, collection)
The DAV:successors collection of a revision contains the revisions
whose DAV:predecessor is that revision.
<!ELEMENT successors (href*)>
3.5.4 AV:labels (readonly, mutable)
This property is used to identify labels that are associated with a
specific revision.
<!ELEMENT labels (label*)>
<!ELEMENT label (#PCDATA)>
Value: segment
Since revision labels are only exposed to a user as a simple
mnemonic tag for selecting a specific revision, embedding advanced
XML facilities for character set tagging, character set encoding,
and language tagging would not be appropriate. For label
applications that are not exposed to a user, the standard URL
encoding techniques will provide a client with sufficient
flexibility in defining label formats.
Since a revision label can be specified in a Target-Selector
header, clients should limit the length of a revision label to be
compatible with common header length constraints.
3.5.5 AV:checkin-date (readonly)
This property contains the date when the revision was checked in.
This property is automatically assigned and is formatted using
ISO8061.
<!ELEMENT checkin-date (#PCDATA)>
Value: date-time
3.5.6 DAV:workspaces (readonly, collection)
This property is a collection of the workspaces that contain
working resources whose DAV:predecessor is this revision.
<!ELEMENT workspaces (href)>
3.5.7 DAV:versioned-resource (readonly, resource)
The DAV:versioned-resource of a revision is the versioned resource
whose DAV:revisions collection contains this revision.
<!ELEMENT versioned-resource (href)>
3.5.8 DAV:activity (readonly, resource) <Activity>
The DAV:activity property of a revision is the DAV:activity of the
working resource from which the revision was created.
<!ELEMENT activity href)>
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3.5.9 AV:merge-predecessors (mutable, collection) <Activity>
The DAV:merge-predecessors collection of a revision contains the
revisions whose contents were explicitly merged by the client into
that revision. The client is free to add or delete members to this
collection to more accurately reflect the contents of that
revision.
A BIND request is used to add a merge predecessor. When the
Destination collection of a BIND request is the DAV:merge-
predecessors of a revision of a versioned resource, the request-URL
of the BIND MUST identify a revision of that versioned resource. A
DELETE request is used to delete a merge predecessor.
<!ELEMENT merge-predecessors (href)>
3.5.10 DAV:merge-successors (mutable, collection) <Activity>
The DAV:merge-successors collection of a revision contains the
revisions whose DAV:merge-predecessors collection contains that
revision.
A BIND request is used to add a merge successor. When the
Destination collection of a BIND request is the DAV:merge-
successors of a revision of a versioned resource, the request-URL
of the BIND MUST identify a revision of that versioned resource. A
DELETE request is used to delete a merge successor.
<!ELEMENT merge-successors (href)>
3.6 Working Resource Properties
WebDAV versioning introduces the following additional properties
for a working resource:
3.6.1 DAV:predecessor (read-only, resource)
This property contains the revision that was checked out to create
this working resource.
<!ELEMENT predecessor (href)>
3.6.2 DAV:checkin-policy
The DAV:checkin-policy property of a working resource describes any
special processing that should be performed when this working
resource is checked in. The following are defined values for
DAV:checkin-policy.
DAV:identical-abort - the CHECKIN should fail if the working
resource is identical to its DAV:predecessor.
DAV:identical-uncheckout - if the working resource is identical to
its DAV:predecessor, remove the working resource without creating a
new revision.
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DAV:uncheckout - remove the working resource without creating a new
revision
DAV:overwrite - the working resource should be copied into its
DAV:predecessor instead of creating a new revision. This CHECKIN
will succeed only if the server supports mutable revisions.
DAV:keep-checked-out - create a new revision but does not delete
the working resource. The DAV:predecessor of the working resource
is changed to be the new revision.
<!ELEMENT checkin-policy (identical-abort | identical-uncheckout |
uncheckout
| overwrite | keep-checked-out | ANY)* >
<!ELEMENT identical-abort EMPTY>
<!ELEMENT identical-uncheckout EMPTY>
<!ELEMENT uncheckout EMPTY>
<!ELEMENT overwrite EMPTY>
<!ELEMENT keep-checked-out EMPTY>
3.6.3 DAV:merge-predecessors (collection) <Activity>
The DAV:merge-predecessors collection of a working resource
contains the revisions whose contents were explicitly merged by the
client into that working resource. It is identical in behavior to
the corresponding property for revisions.
3.6.4 DAV:activity (readonly, resource) <Activity>
The DAV:activity property of a working resource is the DAV:current-
activity of the workspace when the working resource was checked
out.
<!ELEMENT activity (href)>
3.7 Workspace Properties
WebDAV versioning introduces the following additional properties
for a workspace:
3.7.1 DAV:working-resources (readonly, collection)
The DAV:working-resources collection contains the working resources
that are checked out into this workspace.
<!ELEMENT working-resources (href)>
3.7.2 AV:revision-selection-rule
If there is no working resource in a workspace for a given
versioned resource, the DAV:revision-selection-rule of the
workspace specifies the revision of that versioned resource is
selected by that workspace. Since the working resources checked out
into a workspace take priority over revisions selected by the
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revision selection rule, the target of a versioned resource in a
workspace is the working resource in that workspace for that
versioned resource, else the revision selected by the workspace
revision selection rule. To ensure that working resources continue
to be visible in a workspace after they are checked in, the
DAV:current-label or DAV:current-activity of a workspace is usually
the first element of the DAV:revision-selection-rule. If the
DAV:revision-selection-rule is not set or is empty, the workspace
will select no revision for any versioned resource.
The DAV:revision-selection-rule property contains an XML element.
Semantically, a revision selection rule (or RSR) element can be
applied to an arbitrary versioned resource, and will either select
a particular revision of that versioned resource or select no
revision of that versioned resource. If it selects a particular
revision, it may also detect a conflict (e.g. when there were
multiple candidates for selection). A document describing the
conflicts can be obtained through a conflict REPORT request.
<!ELEMENT revision-selection-rule
(href | label | rsr-latest | rsr-or | rsr-merge)>
<!ELEMENT rsr-latest EMPTY>
<!ELEMENT rsr-or (href | label | rsr-or | rsr-merge)*>
<!ELEMENT rsr-merge (href | label | rsr-or | rsr-merge)*>
An href element contains the URL of a baseline, an activity, a
configuration, or a workspace.
If the href identifies a baseline, and the baseline contains a
revision of the versioned resource, that revision is selected;
otherwise, no revision is selected. A baseline never generates a
conflict.
If the href identifies an activity, and the DAV:revisions
collection of the activity contains one or more revisions of the
versioned resource, then the latest revision in that activity is
selected. The semantics of activities ensures that there always is
a unique latest revision for an activity. If the activity contains
no revisions of the versioned resource, the activity selects no
revisions of that versioned resource. If the DAV:needed-activities
collection of an activity is non-empty, then the activity acts like
a DAV:rsr-merge element that contains that activity and each of the
DAV:needed-activities. An activity element can generate conflicts
only if the DAV:needed-activities collection is non-empty.
If the href identifies a configuration, and the configuration
contains a revision of the versioned resource, that revision is
selected by the configuration; otherwise, no revision is selected.
To avoid revision selection circularities, a versioned
configuration MUST not be specified in a revision selection rule,
but a configuration revision may. A configuration never generates
a conflict.
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If the href identifies a workspace, then the behavior of that
element is identical to the behavior of the DAV:revision-selection-
rule of that workspace.
If the revision selection rule element is a label, and a revision
of the versioned resource has that label, that revision is
selected; otherwise, no revision is selected. A label element
never generates a conflict.
A DAV:rsr-latest element selects the revision of that versioned
resource with the latest DAV:creationdate. A DAV:rsr-latest
element never generates a conflict.
A DAV:rsr-or element contains a sequence of RSR elements. The
behavior of a DAV:rsr-or element is identical to the behavior of
the first element in this sequence that selects a revision of the
versioned resource. If no element selects a revision, then the
DAV:rsr-or element selects no revision of that versioned resource.
A DAV:rsr-merge element contains a sequence of RSR elements. If
one of the elements in this sequence selects a revision that is the
descendent of all of the other revisions selected by elements in
this sequence, then that revision is selected by the DAV:rsr-merge
element. If no selected revision is a descendent of all the other
selected revisions, then the result of the DAV:rsr-merge is a
"conflict". A conflicts REPORT request can be used to identify the
conflicts.
3.7.3 DAV:no-checkout
The DAV:no-checkout property of a workspace indicates that no new
working resources can be created in that workspace.
<!ELEMENT no-checkout (#PCDATA)>
Value: boolean
3.7.4 DAV:current-label
The DAV:current-label property of a workspace can contain a
revision label. When a working resource in a workspace is checked
in, it will be given this label.
<!ELEMENT current-label (#PCDATA)>
Value: segment
3.7.5 DAV:current-activity (resource) <Activity>
The DAV:current-activity property of a workspace is the activity
that is currently being performed in that workspace. A new
working resource in a workspace will have its DAV:current-activity
property set to this activity.
<!ELEMENT current-activity (href)>
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3.8 Activity Properties <Activity>
WebDAV versioning introduces the following additional properties
for an activity:
3.8.1 DAV:revisions (readonly, collection)
The DAV:revisions collection of an activity contains all revisions
whose DAV:activity property contains this activity.
<!ELEMENT revisions (href)>
3.8.2 DAV:required-activities (collection)
The DAV:required-activities collection of an activity contains the
other activities that form a part of the logical change being
captured by the activity. The DAV:needed-activities of an activity
contribute to the revision selection behavior of that activity when
it is used in a revision selection rule. The purpose of this
property is to identify other activities that are a prerequisite to
this activity.
<!ELEMENT required-activities (href)>
3.8.3 DAV:workspaces (readonly, collection)
The DAV:workspaces collection of an activity contains the
workspaces that currently have that activity as its DAV:current-
activity.
<!ELEMENT workspaces (href)>
3.9 Baseline Properties <Versioned-Collection>
WebDAV versioning introduces the following additional properties
for a baseline:
3.9.1 DAV:baseline-id (readonly)
The DAV:baseline-id is an identifier assigned to a baseline by the
server. A baseline cannot be given a DAV:baseline-id that has been
given to any other baseline of that versioned collection, even a
baseline that has been deleted.
<!ELEMENT baseline-id (#PCDATA)>
Value: segment
3.9.2 DAV:predecessor (readonly, resource)
The DAV:predecessor of a baseline is the baseline that selected by
the workspace when the baseline was created.
<!ELEMENT predecessor (href)>
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3.9.3 DAV:successors (readonly, mutable, collection)
This property identifies the baselines whose DAV:predecessor is
this baseline. It is identical in behavior to the corresponding
property for revisions.
3.9.4 DAV:versioned-resource (readonly, resource)
This property identifies the versioned collection that contains
this revision. It is identical in behavior to the corresponding
property for revisions.
3.9.5 DAV:merge-predecessors (mutable, collection)
This property identifies the baselines whose contents were
explicitly merged by the client into that baseline. It is identical
in behavior to the corresponding property for revisions.
3.9.6 DAV:merge-successors (mutable, collection)
This property identifies the baselines whose DAV:merge-predecessors
collection contains a binding to this baseline. It is identical in
behavior to the corresponding property for revisions.
3.9.7 DAV:activity (readonly, resource)
This property identifies the DAV:current-activity of the workspace
when the baseline was created.
<!ELEMENT activity (href)>
3.10 Repository Properties <Versioned-Collection>
WebDAV versioning introduces the following additional properties
for a repository:
3.10.1 DAV:versioned-resources (readonly, collection)
The DAV:versioned-resources collection of a repository contains the
set of versioned resources maintained by that repository. The name
of a versioned resource in the DAV:versioned-resources collection
is its DAV:versioned-resource-id. When a member of the
DAV:versioned-resources collection is the request-URL of a request
with no Target-Selector header, the request MUST be applied to the
versioned resource itself, and not to the default target of the
versioned resource. This provides a mechanism for versioning
unaware clients to access the properties of versioned resources.
<!ELEMENT versioned-resources (href)>
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3.10.2 DAV:root-versioned-collection (readonly, resource)
The DAV:root-versioned-collection of a repository is the member of
DAV:versioned-resources that can be exposed with a BIND operation
in another part of the URL namespace.
<!ELEMENT root-versioned-collection (href)>
3.10.3 DAV:activities (collection)
The DAV:activities collection of a repository contains the set of
activities maintained by that repository. New activities can be
added to the DAV:activities collection of a repository with a
MKRESOURCE request. A server MAY restrict the creation of new
activities to only occur in a DAV:activities collection of a
repository.
<!ELEMENT activities (href)>
3.10.4 DAV:configurations (collection)
The DAV:configurations collection of a repository contains the set
of configurations maintained by that repository. New
configurations can be added to the DAV:configurations collection of
a repository with a MKRESOURCE request. A server MAY restrict the
creation of new activities to only occur in a DAV:configurations
collection of a repository.
<!ELEMENT configurations (href)>
3.10.5 DAV:workspaces (collection)
The DAV:workspaces of a repository contains the set of workspaces
maintained by that repository. A workspace of a repository MAY be
able to perform target selection for versioned resources in another
repository. New workspaces can be added to the DAV:workspaces
collection of a repository with a MKRESOURCE request. A server MAY
restrict the creation of new workspaces to only occur in a
DAV:workspaces collection of a repository.
<!ELEMENT workspaces (href)>
3.10.6 DAV:default-workspace (resource)
The DAV:default-workspace of a repository specifies the default
workspace for all versioned resources in that repository.
<!ELEMENT default-workspace (href)>
4 EXISTING METHODS
This section describes the extensions to the existing WebDAV
methods. Under versioning, these methods have all of the WebDAV
functionality with the following extensions.
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4.1 GET
When the request-URL of a GET identifies a versioned resource, the
GET is applied to the target of that versioned resource.
4.2 PUT
When the request-URL of a PUT identifies a versioned resource, the
PUT is applied to the target of that versioned resource.
When PUT is applied to a revision of a versioned resource, the PUT
MUST fail unless the versioned resource has a DAV:auto-version
property and no Target-Selector header has been specified. In this
case, the revision is checked out into the default workspace, the
PUT is applied to the resulting working resource, and the working
resource is checked in.
When PUT is applied to a null resource that is an internal member
of a working collection, a new versioned resource is created whose
initial revision is the resource resulting from the PUT.
When PUT is applied to a null resource in a revision of a versioned
collection, the PUT MUST fail unless the versioned collection has a
DAV:auto-version property and no Workspace or Revision-Selection
header has been specified. In this case, the versioned collection
is checked out into the default workspace, a new versioned resource
is created in that working collection, the new versioned resource
is checked out into the default workspace, the PUT is applied to
the resulting working resource, the working resource is checked in,
and the working collection is checked in.
When a PUT is applied to a workspace, activity, configuration,
baseline, or versioned resource , it fails.
4.3 PROPFIND
When the request-URL of a PROPFIND identifies a versioned resource,
the PROPFIND is applied to the target of that versioned resource.
If a property is a resource property and the DAV:expand-property-
resource is specified under a DAV:prop element in a PROPFIND
request body, selected properties of the property resource URL of
that property will be returned in the PROPFIND response instead of
the href value returned by default for that property resource.
4.4 PROPPATCH
When the request-URL of a PROPPATCH identifies a versioned
resource, the behavior of the PROPATCH is similar to that of PUT.
In particular, when PROPPATCH is applied to a property of a
revision, it MUST fail unless the property is mutable or the
versioned resource has a DAV:auto-version property.
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4.5 COPY
When the request-URL or Destination collection of a COPY identifies
a versioned resource, the COPY is applied to the target of that
versioned resource.
When a COPY request is applied to a workspace, activity,
configuration, baseline, or versioned resource, it fails. An
explicit MKRESOURCE request must be used to create resources of
those types.
4.6 DELETE
When a DELETE request is applied to a member of a working
collection, the specified binding is deleted from that working
collection.
When a DELETE request with an All-Bindings header is applied to a
workspace, the workspace and all working resources of that
workspace are also deleted. When a DELETE request with an All-
Bindings header is applied to a repository, all bindings to the
versioned resources, activities, and configurations in that
repository are also deleted. When a DELETE request with an All-
Bindings header is applied to a versioned resource, all bindings to
all revisions of that versioned resource are also deleted. If any
of the specified bindings cannot be deleted, the DELETE request
MUST fail.
4.7 BIND
When the request-URL of a BIND identifies a versioned resource, the
BIND is applied to that versioned resource, not to the target of
that versioned resource. When the Destination collection of the
BIND is a versioned collection, the request-URL MUST identify a
versioned resource, and the new binding is made in the target of
that versioned collection.
When the Destination collection of the BIND is a configuration, the
request-URL MUST identify a revision, and the Destination binding
name MUST be the versioned-resource-id of that revision.
4.8 MOVE
When the request-URL of a MOVE identifies a versioned resource,
the MOVE is applied to that versioned resource, not to the target
of that versioned resource. When the Destination collection of the
BIND is a versioned collection, the new binding is made in the
target of that versioned collection.
4.9 LOCK
A write lock on a versioned resource checks out the target of that
versioned resource into the default workspace.
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4.10 UNLOCK
An UNLOCK of a write lock checks in the working resource that was
created by the LOCK request.
4.11 OPTIONS
The OPTIONS method allows the client to discover the level of
versioning support provided by a server.
The following defines the BNF for the Versioning header:
Versioning := "Versioning" ":" Ver-level
Ver-level := "Core"
| "Activity"
| "Versioned-Collection"
5 NEW METHODS
WebDAV versioning introduces two new methods, MKRESOURCE and
REPORT, that are not specific to versioning but are needed to
support the versioning extensions.
5.1 MKRESOURCE
The MKRESOURCE method requests the creation of a resource and
initialization of its properties. It allows resources other than
standard data containers and collections to be created and their
properties initialized in one atomic operation.
Preconditions:
If the Overwrite header is not present or is set to 'F', a resource
MUST NOT exist at the Request-URL.
If the Overwrite header is set to 'T' and a resource exists at the
Request-URL, a DELETE request on that Request-URL MUST succeed.
It MUST be possible to atomically create the resource at the
Request-URL and initialize its properties as specified in the
request body of the MKRESOURCE request.
Request Marshalling:
The location of the new resource to be created is specified by the
Request-URL.
An Overwrite header MAY be specified.
The request body of the MKRESOURCE method MUST consist of the
DAV:propertyupdate XML element defined in Section 12.13 of
[WebDAV].
Semantics:
A new resource with an empty body is created at the request-URL.
Property initialization is carried out using PROPPATCH semantics.
The type of resource to create is specified by the DAV:resourcetype
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property. If the DAV:resourcetype property is not specified, the
resource created will be a standard data container.
If the Overwrite header is set to 'T' and MKRESOURCE is applied to
an existing resource, a DELETE request is applied to the request-
URL prior to MKRESOURCE processing.
Postconditions:
After the successful execution of MKRESOURCE, a new resource
exists. The body of the new resource is empty, and the initial
values of the properties of the new resource are those specified in
the property update directives in the request body.
Response Marshalling:
Responses from a MKRESOURCE request SHOULD NOT be cached, as
MKRESOURCE has non-idempotent semantics.
The following status codes can be expected in responses to
MKRESOURCE:
201 (Created): The new resource was successfully created.
207 (Multi-Status): This response is generated if (1) the deletion
of a resource other than the one identified by the Request-URL
could not be completed, in which case the response is as defined in
Section 8.6.2 of [WebDAV], or (2) an error was encountered while
initializing the properties of the resource, in which case the
response is as defined in Section 8.2.1 of [WebDAV].
403 (Forbidden): The server does not allow the creation of the
requested resource type at the requested location, or the parent
collection of the request-URL exists but cannot accept members.
409 (Conflict): A resource cannot be created at the request-URL
until one or more intermediate collections have been created.
412 (Precondition Failed): The Overwrite header is not present or
is set to 'F', and a resource exists at the request-URL.
423 (Locked): A locked resource exists at the request-URL and the
lock token was not passed in with the request.
507 (Insufficient Storage): The server does not have sufficient
space to record the state of the resource.
5.1.1 New DAV:resourcetype Values
The DAV:resourcetype property for a versioned resource, workspace,
activity, baseline, and configuration resource must be
DAV:versioned-resource-resourcetype, DAV:workspace-resourcetype,
DAV:activity-resourcetype, DAV:baseline-resourcetype,
DAV:configuration-resourcetype, respectively.
5.1.2 Example - MKRESOURCE
MKRESOURCE /project1 HTTP/1.1
Host: www.foo.com
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Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:propertyupdate xmlns:D="DAV:">
<D:set>
<D:prop>
<D:resourcetype>workspace</D:resourcetype>
</D:prop>
</D:set>
</D:propertyupdate>
>>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.foo.com/bar.html</D:href>
<D:propstat>
<D:prop><D:resourcetype/></D:prop>
<D:status>HTTP/1.1 409 Conflict</D:status>
</D:propstat>
<D:responsedescription>Existing resource could not be
deleted</D:responsedescription>
</D:response>
</D:multistatus>
5.2 REPORT
The REPORT request is an extensible mechanism for obtaining
information about a resource. This differs from OPTIONS in that
the information provided is dynamic. This document defines three
report types: DAV:available-report, DAV:compare-report and
DAV:conflict-report. The REPORT method MUST not change the state
of any resource managed by the server.
Request Marshalling:
The resource that is the target of the report is specified by the
request-URL.
A Depth header MAY be specified.
The request body of the REPORT method MUST consist of a DAV:report-
request XML element.
Response Marshalling:
The response body of the REPORT method MUST consist of a
DAV:report-response XML element.
The following status codes are used to transmit MKRESOURCE results
back to the client.
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200 (OK) û Generated on successful completion of the requested
report. The body of the response is marshaled as a DAV:report-
response.
5.2.1 DAV:report-request
Describes a report request.
<!ELEMENT report-request
(DAV:available-report-request
| DAV:conflict-report-request
| DAV:compare-report-request
| ANY)>
5.2.2 DAV:report-response
A DAV:report-response contains an entire report. A response can be
for one of the standard reports (reports, conflicts, or compare) or
for a server-defined report. The form of server-defined requests
is not specified.
<!ELEMENT report-response status
(available-report-response
| conflicts-report-response
| compare-report-response
| ANY)>
5.3 Available REPORT
The list of reports supported by the resource identified by the
request-URL.
5.3.1 DAV:available-report-request
No additional information is required for available-report
requests.
<!ELEMENT available-report-request EMPTY>
5.3.2 DAV:available-report-response
A DAV:available-report-response is a comma separated list of the
supported reports.
<!ELEMENT available-reports-response
(DAV:available-report-request
| DAV:conflict-report-request
| DAV:compare-report-request
| ANY)>
5.3.3 Example - Available REPORT
>>Request
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REPORT http://www.webdav.org/myCollection HTTP/1.1
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Target-Selector: workspace
http://www.webdav.org/repo/workspaces/public
<?xml version="1.0" encoding="utf-8" ?>
<D:report-request xmlns:D="DAV:">
<D:available-report-request/>
</D:report-request>
>>Response
HTTP/1.1 200 OK
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Target-Selector: workspace
http://www.webdav.org/repo/workspaces/public
<?xml version="1.0" encoding="utf-8" ?>
<D:report-response xmlns:D="DAV:">
<D:available-report-response>
<DAV:available-report-request/>
<DAV:conflict-report-request/>
</D:reports-response>
</D:report-response>
5.4 Conflict REPORT
A conflict report describes the conflicts in a specified workspace
for a specified resource or for all the members of a specified
versioned collection. Conflicts occur when the workspace revision
selection rule selects more than one revision of a particular
versioned resource, resulting in ambiguous revision selection. The
resource to test is specified by the request-URL. Conflicts are
checked in the workspace specified in the Target-Selector header.
The Target-Selector, if given, MUST be a workspace URL. If the
Target-Selector header is not given, the default workspace is used.
Conflicts for all resources transitively reachable from the
request-URL are reported according to the value of the Depth
header. If the Depth header is not specified, the value infinity
is assumed. Conflicts in resources reachable only via a versioned
collection which is itself ambiguous are not reported.
5.4.1 DAV:conflict-report-request
<!ELEMENT conflict-report-request EMPTY>
5.4.2 DAV:conflict-report-response
A DAV:conflict-report-response contains a DAV:conflict element for
each versioned resource for which the workspace produced a
conflict.
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<!ELEMENT conflicts-report-response (conflict*)>
5.4.3 DAV:conflict
The DAV:conflict element contains the URL of a versioned resource
for which the revision selection rule generated a conflict, a
DAV:common-ancestor for the conflict, and two or more
DAV:contributor elements for the conflict.
<!ELEMENT conflict (href, common-ancestor, contributor,
contributor+)>
5.4.4 DAV:common-ancestor
The DAV:common-ancestor element identifies the revision id of a
revision that is a common ancestor of all the DAV:contributor
elements for a particular conflict.
<!ELEMENT common-ancestor (#PCDATA)>
Value: segment
5.4.5 DAV:contributor
The DAV:contributor element identifies the revision id of a
revision that is selected by an element of the revision selection
rule but that is not an ancestor of any of the other revisions
selected by the revision selection rule.
<!ELEMENT contributor(#PCDATA)>
Value: segment
5.4.6 Example - Conflict REPORT
>>Request
REPORT http://www.webdav.org/myCollection HTTP/1.1
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Target-Selector: workspace
http://www.webdav.org/repo/workspaces/public
<?xml version="1.0" encoding="utf-8" ?>
<D:report-request xmlns:D="DAV:">
<D:conflicts-report-request/>
</D:report-request>
>>Response
HTTP/1.1 200 OK
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Target-Selector: workspace
http://www.webdav.org/repo/workspaces/public
<?xml version="1.0" encoding="utf-8" ?>
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<D:report-response xmlns:D="DAV:">
<D:conflicts-report-response>
<D:conflict>
<D:href>http://www.webdav.org/repo/vr/vr732</D:href>
<D:common-ancestor>revisionid:3</D:common-ancestor>
<D:contributor>revisionid:5</D:contributor>
<D:contributor>revisionid:4</D:contributor>
</D:conflict>
</D:conflicts-report-response>
</D:report-response>
5.5 Compare REPORT
A compare REPORT identifies the differences between the resource
identified by the request-URL (base) and the resources specified in
the body of the request (targets). The comparison is carried out
transitively on any children of the resources according to the
value of the Depth header. If the Depth header is not specified,
the value infinity is assumed. Resources appearing in a target but
not in the base are described by DAV:added elements, resources
appearing in the base but not a target are described by DAV:deleted
elements, and resources appearing in both base and target but
having different states are described by DAV:changed elements.
Resource content comparison is not specified, though servers MAY
provide it.
5.5.1 DAV:compare-request
A DAV:compare- request contains the URL's of the resources to be
compared with the resource identified by the request URL..
<!ELEMENT compare-request (href*)>
5.5.2 DAV:compare-response
A DAV:compare-response identifies the differences between two
resources. These differences are indicated by appropriate
DAV:added, DAV:deleted, and DAV:changed elements. For example, if
a DAV:compare-request is applied to two baselines, the DAV:compare-
response contains the revisions that are selected by one baseline
but not the other.
<!ELEMENT compare-response (added*, deleted*, changed*)>
5.5.3 DAV:added
A DAV:added element identifies something that appears in a
particular target resource but not in the base.
<!ELEMENT added (href, ANY>
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5.5.4 DAV:deleted
A DAV:deleted element identifies something that appears in the base
resource but not in a particular target.
<!ELEMENT deleted (href, ANY)>
5.5.5 DAV:changed
A DAV:changed element identifies information that is in both the
base and the target but that has changed in some way. For example,
when two baselines are being compared, a DAV:changed element can
identify a versioned resource if the baseline select different
revisions of that versioned resource.
<!ELEMENT changed (href, ANY)>
5.5.6 Example - Compare REPORT
>>Request
REPORT /myCollection HTTP/1.1
Host: www.foo.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
Depth: 1
<?xml version="1.0" encoding="utf-8" ?>
<D:report-request xmlns:D="DAV:">
<D:compare-request>
<href>http://www.foo.com/myOtherCollection</href>
</D:compare-request>
</D:report-request>
>>Response
HTTP/1.1 200 OK
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:report-response xmlns:D="DAV:">
<D:compare-response>
<D:added>
<href>http://www.foo.com/myOtherCollection</href>
<href>http://www.foo.com/myOtherCollection/foo.html</href>
</D:added>
<D:deleted>
<href>http://www.foo.com/myOtherCollection</href>
<href>http://www.foo.com/myCollection/bar.html</href>
</D:deleted>
</D:compare-response>
</D:report-response>
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6 NEW VERSIONING METHODS
WebDAV versioning introduces a CHECKOUT and a CHECKIN method.
6.1 CHECKOUT
The CHECKOUT method can be applied to a revision of a versioned
resource to produce a working resource that is a modifiable copy of
that revision. If the workspace for the working resource is not
specified in the Target-Selector header, the server will select a
workspace for it. After a CHECKOUT on a request-URL succeeds, a
subsequent request on that request-URL that specifies that
workspace in a Target-Selector header will be applied to that
working resource. A CHECKIN request applied to that working
resource can be used to create a new revision of that working
resource.
Preconditions:
The request-URL MUST identify either a revision or a versioned
resource whose target is a revision. This is the "selected
revision". The versioned resource for the revision is the
"selected versioned resource".
If the DAV:single-checkout property of the selected versioned
resource is set, the DAV:workspaces collection of the selected
revision MUST have no members.
If the Target-Selector header specifies a workspace, the DAV:no-
checkout property of that workspace MUST not be set.
If the Target-Selector header specifies a workspace, at least one
of the DAV:current-activity or the DAV:current-label property of
that workspace MUST be set.
If the Target-Selector header specifies a workspace with a
DAV:current-activity property, the DAV:workspaces collection of
that activity must be empty.
If the Target-Selector header specifies a workspace, the
DAV:workspaces collection of the revision MUST not contain that
workspace.
Request Marshalling:
The request-URL specifies the revision to check out.
The workspace for the working resource MAY be specified in the
Target-Selector header.
Semantics:
The CHECKOUT method creates a working resource that is a copy of
the revision. If a workspace for the working resource is not
specified in the Target-Selector header, the server allocates a
workspace for the new working resource. The workspace containing
the working resource is the "selected workspace".
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Postconditions:
The DAV:predecessor of the new working resource is set to the
selected revision.
The DAV:workspace of the new working resource is set to the
selected workspace.
The selected workspace is added to the DAV:workspaces collection of
the selected revision.
The selected versioned resource is added to the DAV:checked-out
collection of the selected workspace.
If the DAV:current-activity property of the selected workspace is
set, the DAV:activity property of the working resource is set to
that activity.
Response Marshalling:
Results from a CHECKOUT request MUST NOT be cached as CHECKOUT has
non-idempotent semantics.
The CHECKOUT request response MUST contain a DAV:response XML
element, as defined in section 12.9.1 of [RFC2518]. The
DAV:response MUST contain a DAV:href containing the DAV:versioned-
resource property of the selected revision, followed by either a
DAV:status containing an error status or a DAV:propstat element
describing properties of the new working resource. The
DAV:workspace property of the working resource must be included in
the DAV:prop element.
The following status codes can appear in the DAV:status element.
201 (Created) - The working resource was successfully created.
404 (Not Found) û The request-URL did not identify a resource.
405 (Method Not Allowed) û The selected resource is not a revision
or the specified Target-Selector is invalid.
409 (Conflict) û Any other violated pre-condition of the CHECKOUT
request.
6.1.1 Example - CHECKOUT
>> REQUEST
CHECKOUT http://www.webdav.org/file HTTP/1.1
Target-Selector: http://www.webdav.org/workspaces/mywksp
Content-type: text/xml; charset="utf-8"
<? xml version="1.0" encoding="utf-8" ?>
<D:propertyupdate xmlns:D="DAV:">
<D:set>
<D:prop>
<D:checkin-policy>
<D:keep-checked-out/> </D:checkin-policy>
<D:comment>
Add animated logo. </D:comment> </D:prop> </D:set>
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</D:propertyupdate>
>> RESPONSE
HTTP/1.1 201 Created
Target-Selector: http://www.webdav.org/workspaces/mywksp
Content-type: text/xml; charset="utf-8"
<?xml version="1.0" encoding="utf-8" ?>
<D:response xmlns:D="DAV:">
<D:href>http://www.webdav.org/file</D:href>
<D:propstat>
<D:prop>
<D:workspace>
<D:href>http://www.webdav.org/workspaces/mywksp</D:href>
</D:workspace>
<D:status>HTTP/1.1 201 Created</D:status>
</D:propstat>
</D:response>
6.2 CHECKIN
The CHECKIN method can be applied to a working resource of a
versioned resource to produce a new revision that is a copy of that
working resource. This working resource is the "selected working
resource". The DAV:predecessor of the selected working resource is
the "predecessor revision". The versioned resource that contains
the predecessor revision is the "selected versioned resource". The
DAV:activity of the selected working resource is the "selected
activity". CHECKIN can also be used to cancel the CHECKOUT, and if
the server supports mutable revisions, it can also be used to
overwrite the value of the revision that is the predecessor of the
working resource.
Preconditions:
A CHECKIN request MUST specify a workspace in a Target-Selector
header. This is the "selected workspace".
The request-URL MUST identify a versioned resource whose target in
the selected workspace is a working resource. This is the
"selected working resource".
If DAV:identical-abort is a DAV:checkin-policy, then the selected
working resource MUST not be a copy of the predecessor revision
(ignoring live properties).
Request Marshalling:
The request-URL specifies the working resource.
The Target-Selector header specifies the workspace that contains
the selected working resource. This workspace is the "selected
workspace".
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If a CHECKIN request body is specified, it MUST contain a
DAV:propertyupdate XML element.
Semantics:
The property updates specified in the CHECKIN request body are
applied to the selected working resource.
If DAV:uncheckout is specified, a new revision is not created.
If DAV:identical-uncheckout is specified, a new revision is created
only if the selected working resource is a copy of the predecessor
revision (ignoring live properties).
A copy of the selected working resource (without the DAV:checkin-
policy property) is made a new revision of the selected versioned
resource.
If DAV:keep-checked-out is specified, the working-resource is not
deleted, but the DAV:predecessor property of the working resource
is modified to contain the new revision. Otherwise, the selected
working resource is removed from the selected workspace.
Postconditions:
The selected workspace is deleted from the DAV:workspaces
collection of the predecessor revision.
If the CHECKIN created a new revision, the new revision is added to
the DAV:successors collection of the predecessor revision.
If the CHECKIN created a new revision and there is a selected
activity, the new revision is added to the DAV:revisions collection
of the selected activity.
Response Marshalling:
The following status codes can appear in the DAV:status element.
201 (Created) - The revision was successfully created.
404 (Not Found) û The request-URL did not identify a resource.
405 (Method Not Allowed) û The selected resource is not a working
resource, the specified Target-Selector is invalid, or the
specified properties in the DAV:propertyupdate element are invalid.
409 (Conflict) û Any other violated pre-condition of the CHECKIN
request.
6.2.1 Example - CHECKIN
>> REQUEST
CHECKIN http://www.webdav.org/file HTTP/1.1
Target-Selector: http://www.webdav.org/workspaces/mywksp
Content-type: text/xml; charset="utf-8"
<? xml version="1.0" encoding="utf-8" ?>
<D:propertyupdate xmlns:D="DAV:">
<D:set>
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<D:prop>
<D:checkin-policy>
<D:identical-abort/> </D:checkin-policy>
</D:prop> </D:set>
</D:propertyupdate>
>> RESPONSE
HTTP/1.1 201 Created
Target-Selector: http://www.webdav.org/workspaces/mywksp
Content-type: text/xml; charset="utf-8"
<?xml version="1.0" encoding="utf-8" ?>
<D:response xmlns:D="DAV:">
<D:href>http://www.webdav.org/file</D:href>
<D:status>HTTP/1.1 201 Created</D:status>
</D:response>
7 NEW VERSIONING HEADERS
7.1 Target-Selector
Whenever a server encounters a versioned resource while it is
processing an HTTP request, it is required to act on the target of
the versioned resource, rather than the versioned resource itself.
The Target-Selector header is used to specify how the target is
determined. In particular, the Target-Selector header can specify
a workspace, a revision-id, or a label.
Target-Selector: workspace
"http://www.webdav.org/workspaces/public"
Target-Selector: id "Rev178AE8"
Target-Selector: label "released"
Target-Selector: metadata
When the Target-Selector specifies a workspace, then the working
resource in that workspace for a versioned resource is selected, if
there is one. Otherwise, the revision selected by the
DAV:revision-selection-rule property of that workspace is selected.
When the Target-Selector header specifies a revision-id or a label,
then the specified revision is selected for the versioned resource
identified by the request-URL, but for any other versioned resource
encountered by the server while processing the request, the default
workspace of that versioned resource is used.
When the Target-Selector header specifies metadata, the versioned
resource itself is selected. This allows a client to access the
properties of the versioned resource.
If no Target-Selector header is specified, the DAV:default-
workspace of a versioned-resource is used to perform target
selection for that versioned-resource. An exception to this is the
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DAV:versioned-resources collection of a repository, in which the
versioned resource itself is the target of the versioned resource.
8 INTERNATIONALIZATION CONSIDERATIONS
To be supplied.
9 SECURITY CONSIDERATIONS
To be supplied.
10 SCALABILITY
To be supplied.
11 AUTHENTICATION
Authentication mechanisms defined in WebDAV will also apply to
WebDAV Versioning.
12 IANA CONSIDERATIONS
This document uses the namespace defined by [RFC2518] for XML
elements. All other IANA considerations mentioned in [RFC2518]
also applicable to WebDAV Versioning.
13 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 IETF's procedures 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
Clemm, Kaler [Page 42]
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rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF
Executive Director.
14 ACKNOWLEDGEMENTS
This protocol is the collaborative product of the Delta-V design
team: Jim Amsden (IBM, DeltaV Chair), Geoffrey Clemm (Rational),
Bruce Cragun (Novell), David Durand (INSO), Chris Kaler
(Microsoft), Jeff McAffer (OTI), Bradley Sergeant (Merant), and Jim
Whitehead (UC Irvine). 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.
15 INDEX
To be supplied.
16 REFERENCES
[RFC2026] S.Bradner, "The Internet Standards Process", Harvard,
1996, <http://www.ietf.org/rfc/rfc2026.txt>.
[RFC2068] R.Fielding, J.Gettys, J.C.Mogul, H.Frystyk, and
T.Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2068,
U.C. Irvine, DEC, MIT/LCS, 1997,
<http://www.ietf.org/rfc/rfc2068.txt >.
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", Harvard, 1997,
<http://www.ietf.org/rfc/rfc2119.txt >.
[RFC2396] T.Berners-Lee, R.Fielding, L.Masinter, ôUniform Resource
Identifiers (URI): Generic Syntaxö, MIT/LCS, U.C. Irvine, Xerox,
1998, <http://www.ietf.org/rfc/rfc2396.txt>.
[RFC2518] Y. Goland, E.Whitehead, A.Faizi, S.R.Carter, D.Jensen,
"HTTP Extensions for Distributed Authoring - WEBDAV", Microsoft,
U.C.Irvine, Netscape, Novell, 1999
<http://www.ietf.org/rfc/rfc2518.txt>.
[Binding] J.Slein, E.Whitehead, J.Davis, G.Clemm, C.Fay,
J.Crawford, T.Chihaya, "WebDAV Bindings", Xerox, U.C.Irvine,
CourseNet, Rational, FileNet, DataChannel, 1999,
<http://www.ietf.org/internet-drafts/draft-ietf-webdav-binding-
protocol-01.txt>
[Goals] J.Amsden, C.Kaler, J.Stracke, "Goals for Web Versioning",
IBM, Microsoft, Netscape, 1999, <http://www.ietf.org/internet-
drafts/draft-ietf-webdav-version-goals-01.txt>
17 AUTHORS' ADDRESSES
Clemm, Kaler [Page 43]
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Geoffrey Clemm
Rational Software
20 Maguire Road
Lexington, MA
Email: geoffrey.clemm@rational.com
Christopher Kaler
Microsoft
One Microsoft Way
Redmond WA, 9085-6933
Email: ckaler@microsoft.com
18 OPEN ISSUES
The following list identifies key open issues against this
document:
@ TODO: Allow activity and workspace as CHECKIN request-URL.
@ TODO: Allow CHECKOUT to apply to a versionable resource (like
LOCK).
@ TODO: Describe how MKRESOURCE can be used to create a baseline.
@ TODO: Describe how BIND can mount the root versioned collection
of a repository at an arbitrary URL, even at another authority.
@ Does Versioning have to be a header, or can it be the body of the
OPTIONS response?
@ Couldn't MKRESOURCE be handled just by allowing PROPPATCH to be
applied to a null resource?
@ Do members of a versioned collection revision have to be
versioned resources?
@ Should the server be allowed to restrict where activities,
workspaces, and configurations are located in the URL namespace?
@ Are revision-id's and revision labels in the same namespace (so
that the do not need to be disambiguated in the DAV:revision-
selection-rule and the Target-Selector header)?
@ Do we require locking support for workspace, activity,
configuration, baseline, versioned resource?
@ Should we use the collection protocol to access the "property
collections", or define a separate special add/delete/query for
each?
@ Should we support the "document" variant for properties that
contain a resource URL (i.e. a "property resource")
@ Should we separate the Target-Selector into a Workspace and a
Revision-Selector?
@ Should we allow Depth CHECKOUT?
@ Is there a problem with encoding labels and revision-id's as
segments?
Clemm, Kaler [Page 44]
INTERNET-DRAFT WebDAV Versioning October 22, 1999
@ Can there be any working resources under a collection when a
baseline for that collection is created?
METHOD Template
Preconditions:
{What are the expected preconditions of the method, and what
happens if these preconditions are violated. For example, a common
precondition is the resource identified by the Request-URI must
exist.}
Request Marshalling:
{How are the arguments for the method marshalled. For WebDAV, this
includes stating which headers must be present, and which XML
elements are present in the request body.}
Semantics:
{It clearly states the semantics of the method's operation.}
Postconditions:
{It states the postconditions of the method, giving easily
validated postconditions. Some examples of postconditions are
effects on the state of the resource, including body and
properties, and effects on the resource's parent collection.
Postconditions will often vary depending on the type of the
resource executing the method.}
Response Marshalling:
{It states how the results of the method are marshalled, including
the response for success, and the responses which are generated
when the postconditions cannot be achieved.}
Effect on Existing Resource Types:
{How does this method work on all the different types of resources
defined so far (collections, redirect references, ordinary
resources, etc.)}
Clemm, Kaler [Page 45]