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Versions: (draft-whitehead-webdav-versioning) 00 01 02

   INTERNET-DRAFT                        Chris Kaler, Microsoft, Editor
   draft-ietf-webdav-versioning-01.txt   Jim Amsden, IBM
                                         Goeff Clemm, Rational
                                         Bruce Cragun, Novell
                                         David Durand, BU
                                         Bradley Sergeant, Microfocus
                                         Jim Whitehead, UC Irvine
  
  
   Expires June 20, 1999                 January 20, 1999
  
  
                       Versioning Extensions to WebDAV
  Status of this Memo
  
       This document is an Internet draft. 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 information as Internet drafts.
  
       Internet Drafts are draft documents valid for a maximum of six
       months and can 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 as other than as "work in
       progress".
  
       To learn the current status of any Internet draft please check the
       "lid-abstracts.txt" listing contained in the Internet drafts shadow
       directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
       munnari.oz.au (Pacific Rim), ftp.isi.edu (US East coast) or
       ftp.isi.edu (US West coast).  Further information about the IETF
       can be found at URL: http://www.ietf.org/
  
       Distribution of this document is unlimited.  Please send comments
       to the mailing list at <ietf-dav-versioning@w3.org>, which may be
       joined by sending a message with subject "subscribe" to <ietf-dav-
       versioning-request@w3.org>.
  
       Discussions of the list are archived at
       <URL:http://www.w3.org/Archives/Public/ietf-dav-versioning/>.
  
  Abstract
  
       This document specifies a set of methods, headers, and content-
       types composing DAV Versioning extensions, an application of the
       HTTP/1.1 protocol to version DAV resources.
  
  
  
  
  
  
  
  
  
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                              Table of Contents
  
  VERSIONING EXTENSIONS TO WEBDAV ...........................1
  
  TABLE OF CONTENTS .........................................2
  
  1.  INTRODUCTION ..........................................4
  1.1.DAV Versioning ........................................4
  1.2.Relationship to DAV ...................................4
  1.3.Terms .................................................4
  1.4.Definitions ...........................................4
  1.5.Notational Conventions ................................5
  
  2.  BASIC VERSIONING ......................................5
  2.1.Discovery .............................................6
  2.2.Immutable and Mutable Properties ......................7
  2.3.Versioning a Resource .................................8
  2.4.Immutable and Mutable Revisions .......................8
  2.5.Versioning and COPY/MOVE ..............................9
  2.6.Sharing ...............................................9
  2.7.Default Revision .....................................10
  2.8.Collection Versioning ................................11
  2.9.Basic Revision Properties ............................11
  2.10. Basic Versioning Headers ...........................13
   2.10.1. Revision-Id .....................................13
   2.10.2. Branch-Id .......................................14
   2.10.3. Override-Checkin ................................14
   2.10.4. Revision-Path ...................................14
  
  3.  CHECKING OUT/IN RESOURCES ............................15
  3.1.Checkout .............................................15
  3.2.Checkin ..............................................17
  3.3.Cancelling Checkout ..................................17
  3.4.Enumeration ..........................................18
  
  4.  BRANCHING RESOURCES ..................................18
  
  5.  RESOURCE REPORTS .....................................19
  5.1.Available Reports ....................................20
  5.2.Default History ......................................21
  5.3.Active Checkouts .....................................22
  5.4.Direct Lineage .......................................23
  5.5.Full Lineage .........................................24
  
  6.  CONFIGURATION BASICS .................................26
  6.1.Discovery ............................................27
  6.2.Creating Configurations ..............................28
  6.3.Access Using Configurations ..........................30
  6.4.Deleting Configurations ..............................30
  6.5.Resolution Queues ....................................30
  6.6.Configuration Properties .............................31
  6.7.Headers ..............................................32
  
  7.  CONFIGURATION REPORTS ................................33
  
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  7.1.Configuration Derivation .............................33
  7.2.Configuration Merge Graph ............................34
  
  8.  DYNAMIC CONFIGURATIONS ...............................35
  
  9.  WORKSPACE CONFIGURATIONS .............................37
  9.1.Managing Configuration Content .......................37
  9.2.Default Workspace Configurations .....................38
  
  10. CHECKIN SETS .........................................38
  
  11. VERSION MAPPING ......................................39
  11.1. Discovery ..........................................40
  11.2. Mapping Configurations .............................41
  11.3. Mapping Resource Versions ..........................41
  
  12. THE DAV VERSIONING GRAMMAR ...........................42
  
  13. INTERNATIONALIZATION CONSIDERATIONS ..................42
  
  14. SECURITY CONSIDERATIONS ..............................43
  
  15. SCALABILITY ..........................................43
  
  16. AUTHENTICATION .......................................43
  
  17. IANA CONSIDERATIONS ..................................43
  
  18. COPYRIGHT ............................................43
  
  19. INTELLECTUAL PROPERTY ................................43
  
  20. REFERENCES ...........................................43
  
  21. AUTHOR'S ADDRESSES ...................................44
  
  22. OPEN ISSUES ..........................................44
  
  23. CHANGE HISTORY .......................................45
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  1. INTRODUCTION
  
  
  1.1. DAV Versioning
  
       This document defines DAV Versioning extensions, an application of
       HTTP/1.1 for handling resource versioning in a DAV environment.
       [DAVVERREQ] describes the motivation and requirements for DAV
       Versioning.
  
       DAV Versioning will minimize the complexity of clients so as to
       facilitate widespread deployment of applications capable of
       utilizing the DAV services.  As well, DAV Versioning supports a
       rich level of versioning options for versioning-aware clients.
  
       DAV Versioning consists of:
  
       -  Automatic versioning support for HTTP/1.1-based clients,
  
       -  Basic versioning for DAV Versioning-aware clients,
  
       -  File branching for basic parallel development, and
  
       -  Configuration support for sophisticated  parallel development.
  
  
  1.2. Relationship to DAV
  
       DAV Versioning relies on the resource and property model defined by
       [WebDAV].  DAV Versioning does not alter this model.  Instead, DAV
       Versioning allows clients to version and access DAV-modeled
       resources and histories.
  
  
  1.3. Terms
  
       This draft uses the terms defined in [RFC2068], [WebDAV], and
       [DAVVERREQ].
  
  
  1.4. Definitions
  
       The section defines several terms that are used throughout the
       document specific to DAV versioning.
  
       Versioned Resource - This refers to a resource that is subject to
       versioning (independent of any specific version)
  
       Revision - This refers to a specific version of a versioned
       resource
  
       Revision History - This refers to the set of changes to a versioned
       resource
  
  
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       Working Resource - This refers to a resource that is an
       intermediate revision of a versioned resource.  That is, the
       versioned resource has been "checked out" and this is where changes
       are made until it is ready to be "checked in".  Note that working
       resources are not versioned.
  
       Revision Thread - This refers to a sequence of revisions that have
       been branched for a specific purpose.
  
       Line of Descent - This refers to the sequence of revisions that
       have occurred from the initial revision to a specified revision.
  
  
  1.5. 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. BASIC VERSIONING
  
       The base level of versioning support defined by this specification
       includes both automatic versioning and the basic versioning
       properties defined for all resources.  To support basic versioning,
       resources MUST allow for versioning to occur automatically on
       selected resources whenever immutable aspects are changed, and
       support the properties defined in this section.
  
       Resources that support DAV:versioning MUST also provide additional
       versioning semantics for versioning-aware clients.  This section
       describes these new semantics which include enhancements to
       existing DAV methods, new headers, and new versioning-specific
       methods.
  
       Although the semantics can vary, most versioning systems support
       the notion of indicating intent to modify a document (check-out)
       and then submission of the modified version (check-in).  Typically
       this involves some form of locking (either shared or exclusive).
       As well, many systems support the ability to cancel a check-out or
       undo a recent check-in.  These options are available to the owner
       or to the Administrator.
  
       Users can generally enumerate the current check-outs although they
       may not be able to determine the user in all cases.  Likewise,
       users can review check-ins to see the change history.  Most systems
       allow users to select different versions from the change history
       and present a comparison of the versions.
  
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       Note that locks are not covered in this specification as they are
       addressed by [WebDAV].
  
  
  2.1. Discovery
  
       The OPTIONS method allows the client to discover if a resource
       supports versioning.  The presence of Versioning in the response
       header indicates support for DAV versioning.  This header indicates
       the level of support.
  
       The following defines the BNF for the Versioning header:
  
            Versioning   := "Versioning" ":" URI
  
       The valid values of the URI are:
  
       -  DAV:basicversioning
  
       -  TBD
  
  
  
       This example shows that the /somefolder resource supports
       versioning.
  
       >> Request
  
       OPTIONS /somefolder/ HTTP/1.1
       Host: foobar.com
       Content-Length: 0
  
       >> Response
  
       HTTP/1.1 200 OK
       Date: Tue, 20 Jan 1998 20:52:29 GMT
       Connection: close
       Accept-Ranges: none
       Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Public: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Versioning: DAV:basicversioning
       Content-Length: 0
  
       Since some aspects of DAV versioning require clients to know
       additional information, clients can include a request body that
       specifies that DAV versioning information is desired.  The
       information is returned in the response body, formatted in XML.
  
  
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       >> Request
  
       OPTIONS /somefolder/ HTTP/1.1
       Host: foobar.com
       Content-Length: xxx
       Content-Type: text/xml
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:options xmlns:D="DAV:">
          <D:verinfo/>
       </D:options>
  
       >> Response
  
       HTTP/1.1 200 OK
       Date: Tue, 20 Jan 1998 20:52:29 GMT
       Connection: close
       Accept-Ranges: none
       Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Public: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Versioning: DAV:basicversioning
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:options xmlns:D="DAV:">
          <D:verinfo>
            ...
          </D:verinfo>
       </D:options>
  
       The details of the tags returned are described throughout this
       specification.
  
  
  2.2. Immutable and Mutable Properties
  
       An immutable property is defined as a property that, when changed,
       causes a new revision of a versioned resource to be created.
       Likewise, a mutable property is a property that can be changed
       without having a new revision created.
  
       Resources can support both mutable and immutable properties
       although there MAY be restrictions that the mutability is
       consistent across all resources.
  
       This specification doesn't cover the discovery or management of
       property mutability.
  
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  2.3. Versioning a Resource
  
       By default, a resource may not be subject to versioning.  This can
       be discovered by examining the DAV:isversioned property.  To place
       a non-versioned resource under version control, clients use the
       VERSION method and specify the URI of the resource to version.
       Note that if the specified resource is a collection, then the Depth
       header is used to identify the scope of the operation.  A depth of
       infinity is assumed by default.
  
       The DAV:isautoversioned property indicates if a resource is
       automatically versioned when any immutable aspect of it is changed.
       Resources with automatic versioning allow HTTP/1.1 clients to have
       changes versioned without explicit versioning commands.  This
       applies to any method that modifies a resource (e.g., PUT, MKCOL,
       COPY, MOVE, DELETE, PROPPATCH, ...)
  
       Using the DAV:versioningenabled and DAV:autoversioning tags,
       clients can establish the versioning policy.
  
       >> Request
  
       VERSION /somefolder/ HTTP/1.1
       Host: foobar.com
       Depth: infinity
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:versioning xmlns:D="DAV:">
          <D:versioningenabled>On</D:versioningenabled>
          <D:autoversioning>On</D:autoversioning>
       </D:versioning>
  
       >> Response
  
       HTTP/1.1 200 OK
       Content-Length: 0
  
  2.4. Immutable and Mutable Revisions
  
       By default, the contents of a revision are immutable.  That is,
       once a revision is created, it cannot be altered.  However, in many
       document management systems this is not the case.  To address these
       scenarios, the THAW/FREEZE methods are introduced.  Note that
       support for THAW and FREEZE are optional, but these operations MUST
       fail if not supported.
  
       The THAW method specifies that the indicated revision should be
       made mutable so that subsequent methods can alter the immutable
       aspects of the resource.  The FREEZE method indicates that all
       changes have been made and the revision should be marked immutable
       again.
  
  
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       The DAV:canthaw property indicates if a revision can be thawed.
       Similarly, the DAV:hasthawed property indicates if a revision has
       ever been thawed.  Finally, the DAV:isthawed property specifies if
       the revision is currently thawed (frozen if not).
  
       The following example shows the use of THAW and FREEZE.
  
       >>Request
  
       THAW /foo/bar.htm HTTP/1.1
       Revision-Id: VER:FHF45409
       Host: www.foobar.com
       Content-Length: 0
       ...
  
       PUT /foo/bar.htm HTTP/1.1
       Revision-Id: VER:FHF45409
       Host: www.foobar.com
       Content-Length: xxx
       ...
  
       FREEZE /foo/bar.htm HTTP/1.1
       Revision-Id: VER:FHF45409
       Host: www.foobar.com
       Content-Length: 0
       ...
  
  2.5. Versioning and COPY/MOVE
  
       When a COPY method is issued against a versioned resource or
       revision, only the "current" revision of the versioned resource or
       the specified revision is copied to the specified destination.
       That is, the entire history is NOT copied.
  
       When a MOVE method is issued against a versioned resource the
       "move" SHOULD be represented in the revision history.  That is, a
       MOVE operation CANNOT be represented as a delete and an add.  A
       MOVE operation cannot be issued against a specific revision.
  
  
  2.6. Sharing
  
       Many versioning systems today provide the ability to have a given
       resource visible in multiple parts of the namespace.  In these
       situations, a resource is shared.  That is, changes to the resource
       are visible to all versions.
  
       The WebDAV Advanced Collections working group addresses this need
       with direct referential members.  Support for direct referential
       members is required for DAV versioning.
  
  
  
  
  
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  2.7. Default Revision
  
       If a Revision-Id (or Branch-Id) header is not specified when
       referring to a resource, then the tip (latest) revision (from the
       primary branch) is used, unless a default revision has been
       identified.  To mark a specified revision as the default revision,
       clients use the SETDEFAULT method.  Note that PUT or CHECKIN will
       remove any default version.  Also note that branching a resource
       has no effect on the default revision of the resource, even if the
       default revision is branched.  If the default is removed, the
       default revision is the tip revision of the initial (primary)
       branch of the versioned resource.
  
       Setting the default revision to DAV:none cancels the default
       revision.
  
       >>Request
  
       SETDEFAULT /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:setdefault xmlns:D="DAV:">
          <D:href>VER:HT58GHDW49</D:href>
       </D:setdefault>
  
       >>Response
  
       HTTP/1.1 200 OK
       Content-Length: 0
  
       >>Request
  
       SETDEFAULT /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:setdefault xmlns:D="DAV:">
          <D:none/>
       </D:setdefault>
  
       >>Response
  
       HTTP/1.1 200 OK
       Content-Length: 0
  
  
       If a resource is shared, servers MUST support the ability to set
       different default revisions at each point of the share.
  
  
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       Clients can determine the default revision by examining the
       DAV:revisionid from the default revision.
  
       >>Request
  
       PROPFIND /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:prop>
            <D:revisionid/>
          </D:prop>
       </D:propfind>
  
  2.8. Collection Versioning
  
       Collections can be versioned just like non-collection resources,
       however, they are only versioned when a direct change is made to
       the collection.
  
       It is up to each collection resource to determine if it supports
       default versions.  If it doesn't, then SETDEFAULT requests MUST
       fail.
  
       The Revision-Path header is used to identify specific revisions
       that are part of the "path" to the resource.  This header servers
       as an alternative to "URL munging".  This header can be specified
       on all methods and qualifies the resource named in the method.
  
  
  2.9. Basic Revision Properties
  
       For resources that support versioning, they MUST support the
       following properties using the "DAV:" namespace.  Note that 0/1 is
       used as a FALSE (0) / TRUE (1) indicator.
  
       DAV:isversioned - 0/1 to indicate if the resource is versionable.
       Note that this can be implemented as a read-only property.
  
       DAV:autoversion - 0/1 to indicate if the resource is automatically
       versioned when modified.  Note that this can be implemented this as
       a read-only property.
  
       DAV:revisionid - This is a read-only property that returns a server
       determined id for this specific revision of the resource.  Every
       revision of a resource will have a unique DAV:revisionid.  A
       revision id may be a URL or it may be an arbitrary server-defined
       string.  However, it cannot contain the "," character.  Because it
       is not required to be a URL, the DAV:revisionurl property is
       required to obtain a URI for the specific revision of the resource.
  
  
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       DAV:vresourceid - This is a read-only property that returns a
       server determined id for the versioned resource.  That is, all
       revisions of the resource have the same DAV:vresourceid.  This MUST
       be preserved over MOVE requests and should be globally unique.
  
       DAV:previousrevisionids - This is a read-only property that returns
       the server defined id for the previous revision of the resource.
       An empty value indicates that there are no previous revisions.
       Note that there could be multiple previous versions.  If there are
       multiple revisions, they are returned as a comma-separated list.
       Note that this property returns previous revisions that the server
       determines.  That is, this does not include user identified merged
       revisions.
  
       DAV:distinguishedpredecessorid - This read-only property indicates
       the primary predecessor for a revision in the event they are
       multiple predecessors.
  
       DAV:nextrevisionids - This is a read-only property that returns the
       server defined id for the next revision of the resource.  An empty
       value indicates that there is no subsequent revision.  Note that
       there could be multiple next revisions.  If there are multiple
       revisions, they are returned as a comma-separated list.  Note that
       this property returns successor revisions that the server
       determines.  That is, this does not include user identified merged
       revisions.
  
       DAV:revisionurl - This is a read-only property that returns a URL
       for this specific revision.
  
       DAV:revisionlabel - This property allows the specification of
       textual names that refer to this version of the resource. If there
       are multiple labels, they are returned as a comma separated list.
       Labels MUST be unique for the versioned resource.  That is, no two
       revisions of the same versioned resource can have the same
       DAV:revisionlabel.  As well, DAV:revisionlabel and DAV:revisionid
       properties share the same namespace and there can be no duplicates.
       Servers MAY reserve specific portions of this namespace and return
       an error if a client uses a reserved name as a revision label.
       This property MUST be mutable.
  
       DAV:mergedfrom - This property specifies a comma separated list of
       revision ids from which this revision is purported to be derived.
       This information is provided and managed by the client. This is a
       mutable property.
  
       DAV:mergedto - This property specifies a comma separated list of
       revision ids from which this revision is purported to be merged
       into.  This information is provided and managed by the client. This
       is a mutable property.
  
       DAV:mergedfromunion - This read-only property specified a comma
       separated list of revision ids from which this revision is derived.
  
  
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       This is a union of the DAV:mergedfrom and DAV:previousrevisionids
       properties.
  
       DAV:revisioncomment - This property contains a client-defined
       property associated with the revision.  This as a mutable property.
       This is a mutable property.
  
       DAV:author - The creator of the revision.  This is an arbitrary
       string.
  
       DAV:canthaw - This property indicates if the revision can be THAWed
       for modification.  Servers MAY implement this as read-only.
  
       DAV:hasthawed - This read-only property indicates if the revision
       has ever been thawed.
  
       DAV:isthawed - This read-only property indicates if the revision is
       currently thawed (or frozen if not).
  
       DAV:lastcheckin - This read-only property specifies the date this
       revision was "checked in" in ISO8601 format.
  
  
  2.10.     Basic Versioning Headers
  
       The following sub-sections describe the new version headers that
       MUST be supported for resources that support DAV:versioning.
  
  
  2.10.1.   Revision-Id
  
       The Revision-Id header is used to identify a specific revision of a
       versioned resource.  This header can be specified on all methods
       and qualifies the resource named in the method.  As well, this
       header is included in all replies to indicate the revision of the
       versioned resource used or created.
  
       The BNF for this header is as follows.
  
            Revision-Id := "Revision-Id" ":" RID
            RID       := "*" | Time-Ref | ANY
            Time-Ref     := "Time" "(" ISO8601 ")"
  
       This property allows the specification of criteria that selects a
       specific revision of a resource.  This includes a DAV:revisionid or
       any of the DAV:revisionlabel values to refer to a specific revision
       of the resource.  As well, a configuration (described later) can be
       referenced here to select the default revision associated with the
       configuration.
  
       The use of the Time operator is to select the "current" revision as
       of the specified time.
  
  
  
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       The use of Revision-Id: * is only permitted with PROPFIND to obtain
       properties across all revisions of a versioned resource.
  
  
  2.10.2.   Branch-Id
  
       The Branch-Id header is used to identify a branch (revision
       thread).  The BNF for the header is as follows:
  
            Branch-Id := "Branch-Id" ":" ANY
  
       The Branch-Id can be used anywhere a revision-id is used.  When
       specified, it indicates that the latest version of the indicated
       branch is to be selected as the revision to use for the operation.
  
  
  2.10.3.   Override-Checkin
  
       It is possible that the check-in operation will detect a conflict.
       For example, version 5 was checked out shared, and before it is
       checked back in, version 6 was created.  In these situations, the
       check-in MUST fail indicating a conflict.  Clients can choose to
       branch the resource, merge on the client, or overwrite.  To
       circumvent this check, clients can use the Override-Checkin header.
       This specifies that the check-in operation SHOULD NOT fail (either
       the client has merged to resolve the conflict, or desires an
       overwrite).  The BNF is as follows:
  
            Override-Checkin := "Override-Checkin" ":" ("Yes" | "No")
  
  2.10.4.   Revision-Path
  
       The Revision-Path header allows clients to identify specific
       versions of collections that should be used rather than the default
       revisions.
  
       The BNF for this header is as follows.
  
            Revision-Path := "Revision-Path" ":" Path
            Path         := PItem | (Path PItem)
            PItem         := "/" ANY Rev
            Rev          := | (";" RID)
            RID         := "*" | ANY | "(" ANY ")"
  
       >>Request
  
       GET /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Revision-Path: /foo;VER:HT58GHDW49/bar.htm
       Content-Length: 0
  
       The use of * for a revision is only permitted with PROPFIND to
       obtain properties across all revisions of a versioned resource.
  
  
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  3. CHECKING OUT/IN RESOURCES
  
       For versioning-aware clients, more advanced requests allow them to
       perform specific versioning operations.  These methods are directed
       at a specific URI to alter.
  
       If a resource supports DAV:versioning then it MUST support the
       methods defined in this section.
  
  
  3.1. Checkout
  
       Using the CHECKOUT method, clients can request resources to be
       "checked out".  This involves creating a working resource that is
       not automatically versioned.  Checked out resources must be checked
       in or cancelled. The diagram below illustrates this process:
  
           Revisions of foo.htm:  V1
  
           Checkout is performed: V1
                                   |
                                   +-> Working Resource
  
           Checkin is performed:  V1 -> V2
  
       The body XML indicates an optional checkout comment, an optional
       user token, and locking actions.  The response indicates the
       working resource as well as any requested locks.
  
       The CHECKOUT method causes the creation of the working copy which
       is specified by the Location header in the response.
  
       Clients can optionally request locks to be taken as part of the
       CHECKOUT operation.  If the locks cannot be obtained, the CHECKOUT
       operation MUST fail.  The following table identifies the different
       lock options:
  
  
            Lock      Tags Used       Description
            Target    (DAV: assumed)
  
  
            working   wrlocktype,     Limits access to the newly created
            resource  wrlockscope     working resource
  
  
            revision  revisionlockty  Blocks CHECKOUT/INs against this
                      pe,             revision
                      revisionlocksc
                      ope
  
  
  
  
  
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            branch    branchlocktype  Blocks CHECKOUT/INs against
                      ,               revisions in this branch
                      branchlockscop
                      e
  
  
            versioned vrlocktype,     Blocks CHECKOUT/INs against any
            resource  vrlockscope     revision of the versioned
                                      resource.
  
  
  
  
       The semantics of the tags match those of DAV:locktype and
       DAV:lockscope as specified for the LOCK method.
  
       >>Request
  
       CHECKOUT /foo/bar HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:checkout xmlns:D="DAV:">
          <D:comment>checkout comment</D:comment>
          <D:owner>client-defined token</D:owner>
          <D:wrlocktype><D:write/></D:locktype>
          <D:wrlockscope><D:exclusive/></D:lockscope>
       </D:checkout>
  
       >>Response
  
       HTTP/1.1 201 CREATED
       Location: http://www.foobar.com/tmp/VRJHJWE3493409
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8"?>
       <D:prop xmlns:D="DAV:">
          <D:lockdiscovery>
            <D:activelock>
               <D:wrlocktype><D:write/></D:locktype>
               <D:wrlockscope><D:exclusive/><D:lockscope>
               <D:owner>client-define token</D:owner>
               <D:locktoken>
                 <D:href>opaquelocktoken:rejrei-43343-rereffre</D:href>
               </D:locktoken>
            </D:activelock>
          </D:lockdiscovery>
       </D:prop>
  
       Servers MUST fail this operation if a branch is required.
  
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  3.2. Checkin
  
       When the client has completed changes to a resource and wishes it
       to become part of the revision history, the client must check in
       the resource.  This is performed using the CHECKIN method against
       the working copy.
  
       The DAV:keepcheckedout tag can be specified to indicate that the
       resource should remain checked out.  That is, create a new
       revision, but leave the working copy checked out.
  
       Using XML tags in the request body, clients can specify optional
       checkin information.
  
       >>Request
  
       CHECKIN /tmp/VRJHJWE3493409 HTTP/1.1
       Host: www.foobar.com
       Lock-Token: <opaquelocktoken:rejrei-43343-rereffre>
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:checkin xmlns:D="DAV:">
          <D:comment>checkin comment</D:comment>
       </D:checkin>
  
       >>Response
  
       HTTP/1.1 201 CREATED
       Revision-Id: VER:FREFRI49349
       Content-Length: 0
  
       The reply MUST include the Revision-Id of the newly created
       revision.
  
       It is possible that the check-in operation will detect a conflict.
       Servers MUST fail this operation if a branch is required.  The
       Override-Checkin header is used to resolve these conflicts.
  
  
  3.3. Cancelling Checkout
  
       If a client chooses to cancel a checkout request, the UNCHECKOUT
       method against the working copy.  As well, optional XML body tags
       can be used to supply additional information.
  
       >>Request
  
       UNCHECKOUT /tmp/VRJHJWE3493409 HTTP/1.1
       Host: www.foobar.com
       Lock-Token: <opaquelocktoken:rejrei-43343-rereffre>
       Content-Type: text/xml
       Content-Length: xxxxx
  
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       <?xml version="1.0" encoding="utf-8" ?>
       <D:uncheckout xmlns:D="DAV:">
          <D:comment>cancel checkout comment</D:comment>
       </D:uncheckout>
  
       >>Response
  
       HTTP/1.1 200 OK
       Content-Length: 0
  
  3.4. Enumeration
  
       Refer to the Resource Reports section for details on check-out
       enumeration.
  
  
  4. BRANCHING RESOURCES
  
       For more sophisticated clients, basic resource branching is
       required. Resource branching means that for a given resource, the
       history is not linear.  That is, there are different lines of
       descent.  The diagram below illustrates this.
  
           Revision history    V1 -> V2 -> V3
           Of foo.htm:          |
                                +-> V1.1 -> V1.2
                                      |
                                      +-> V1.1.1
  
       Individual resource branching is common in many versioning systems
       today.  Project branching (configurations) are described in a later
       section. Note that when a collection is branched, the depth of the
       branch is infinity.  There is no way to change this.
  
       A revision is branched using the BRANCH method.  The resource to be
       branched is specified as the target URI for the method.
  
       As well, clients can specify a branch label to identify a created
       branch using the DAV:branchlabel tag.  The reply MUST include a
       Branch-Id header specifying a resource defined branch id or the
       specified branch label if a branch is created.  The label or id can
       be specified in a Branch-Id or Revision-Id header to determine the
       revision to access.
  
       >>Request
  
       BRANCH VER:FHHR4959 HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/html
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:branch xmlns:D="DAV:">
  
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          <D:branchlabel>MyBranch</D:branchlabel>
          <D:comment>branch comment</D:comment>
       </D:branch>
  
       >>Response
  
       HTTP/1.1 201 CREATED
       Branch-Id: MyBranch
       Revision-Id: VER:REUU48583
       Content-Length: 0
  
       When a branch is created, the reply MUST include a Branch-Id
       header.
  
  
  5. RESOURCE REPORTS
  
       Revision history graphs and other reports of a resource are
       accessed via PROPFIND.
  
       Note that resources MAY support multiple styles of history and
       reports.  To enumerate the supported history graphs and reports,
       clients use PROPFIND and the <DAV:availablereports> property.  The
       results indicate a list of the different reports which can,
       themselves, be requested via PROPFIND.
  
       For the examples in this section, assume that the resource /foo.htm
       has the following revision graph:
  
       Revision history     V1 -> V2 -> V3
           Of foo.htm:          |
                                +-> V1.1 -> V1.2
                                      |
                                      +-> V1.1.1
  
       Clients have specified the following merge annotations:
  
       -  V1.2 is a merge of V1.1 and V1.1.1
  
       -  V3 is a merge of V2 and V1.2
  
       As well, the default revision history (those revisions marked as
       the default) is as follows:
  
       -  V1 (the initial revision was created)
  
       -  V2 (a new revision was created)
  
       -  V1 (a client changed the default revision)
  
       -  V3 (an updated revision was created)
  
       Also, the following labels have been specified:
  
  
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       -  V2: Test1
  
       -  V1.1: Test2, Good
  
       -  V1.2: Tested
  
       Additionally, when the V1.1 branch was created, it was labeled
       "MyBranch".
  
  
  5.1. Available Reports
  
       Clients can obtain the available reports for a resource by
       obtaining its DAV:availablereports property.
  
       >>Request
  
       PROPFIND /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:prop>
            <D:availablereports/>
          </D:prop>
       </D:propfind>
  
       >>Response
  
       ...
       <D:multistatus>
          <D:response>
            <D:href>http:/www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:availablereports>
                    <D:report>DAV:defaulthistory</D:report>
                    <D:report>DAV:directlineage</D:report>
                    <D:report>DAV:fulllineage</D:report>
                 </D:availablereports>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
       ...
  
       Note that the report styles MUST be specified as DAV:href values.
  
  
  
  
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       When clients issue PROPFIND requests to obtain reports, they may
       include other properties in the request.  These properties are
       returned for each report item.
  
  
  5.2. Default History
  
       Resources MUST support the DAV:defaulthistory report.  This
       enumerates the historical record of revisions that have been
       visible as the default revision.
  
       Clients can specify the limit parameter to limit the number
       revisions returned.  By definition, revisions are returned in
       reverse chronological order starting with the most recent.
  
       >>Request
  
       PROPFIND /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:defaulthistory limit=20/>
       </D:propfind>
  
       >>Response
  
       ...
       <D:multistatus>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V3</D:revision>
                 <D:revisioncomment>Update it</D:comment>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V1</D:revision>
                 <D:revisioncomment>Update it</D:comment>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
  
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            <D:propstat>
               <D:prop>
                 <D:revisionid>V2</D:revision>
                 <D:revisioncomment>Update it</D:comment>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V1</D:revision>
                 <D:revisioncomment>Update it</D:comment>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
  
  5.3. Active Checkouts
  
       Clients can obtain a list of the active checkouts against a
       resource using PROPFIND and DAV:activecheckouts.
  
       >>Request
  
       PROPFIND /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Revision-Id: VER:FHRJ494059
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:activecheckouts/>
       </D:propfind>
  
       >>Response
  
       HTTP/1.1 207 Multi-Status
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:multistatus xmlns:D="DAV:">
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:checkout>
                    <D:owner>user-specified</D:owner>
                    <D:revisionid>VER:FHER4949</D:revision>
  
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                    <D:href>http://www.foobar.com/foo/bar.htm</D:href>
                    <D:workingcopy>
                      <D:href>http://www.foobar.com/tmp/FHFH34949</D:href>
                    </D:workingcopy>
                 </D:checkout>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
  
  5.4. Direct Lineage
  
       Resources SHOULD support the DAV:directlineage report.  This
       enumerates the direct parent revisions of the resource.
  
       Clients can request that a report be based on the namespace entry
       specified, or the associated DAV:vresourceid.  Clients use the
       scope parameter to specify (name or id).
  
       Clients can specify the limit parameter to limit the number
       revisions returned.
  
       >>Request
  
       PROPFIND /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:directlineage scope="name"/>
       </D:propfind>
  
       >>Response
  
       ...
       <D:multistatus>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V1</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
  
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               <D:prop>
                 <D:revisionid>V2</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V1</D:derivedfrom>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V3</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V3</D:derivedfrom>
                 <D:revisionlabel>Test1</D:label>
                 <D:mergedfrom>V2</D:mergedfrom>
                 <D:mergedfrom>V1.2</D:mergedfrom>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
  
  5.5. Full Lineage
  
       Resources SHOULD support the DAV:fulllineage report.  This
       enumerates the full graph of revisions for this resource.
  
       Clients can request that a report be based on the namespace entry
       specified, or the associated DAV:vresourceid.  Clients use the
       scope parameter to specify (name or id).
  
       Clients can specify the limit parameter to limit the number
       revisions returned.
  
       >>Request
  
       PROPFIND /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:fulllineage scope="name"/>
       </D:propfind>
  
       >>Response
  
       ...
  
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       <D:multistatus>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V1</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V2</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V1</D:derivedfrom>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V3</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V2</D:derivedfrom>
                 <D:revisionlabel>Test1</D:label>
                 <D:mergedfrom>V2</D:mergedfrom>
                 <D:mergedfrom>V1.2</D:mergedfrom>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V1.1</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V1</D:derivedfrom>
                 <D:revisionlabel>Test2</D:label>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
  
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            <D:propstat>
               <D:prop>
                 <D:revisionid>V1.2</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V1.1</D:derivedfrom>
                 <D:branchid>MyBranch</D:branchid>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http://www.foobar.com/foo/bar.htm</D:href>
            <D:propstat>
               <D:prop>
                 <D:revisionid>V1.1.1</D:revision>
                 <D:vresourceid>VER:FFHJE</D:vresource>
                 <D:revisioncomment>Update it</D:comment>
                 <D:derivedfrom>V1.1</D:derivedfrom>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
  
  6. CONFIGURATION BASICS
  
       Many clients require more sophisticated management and organization
       of their versioned data.  For this reason, configuration support is
       defined as part of this specification.
  
       Configuration management is a large space. This specification
       addresses several types of configurations:
  
       -  Dynamic: A dynamic configuration is a collection of specific
          revisions of selected versioned resources based on selection
          rules.  This can be used for labels, floating labels, etc.
  
       -  Workspace: A workspace configuration is a mechanism for tracking
          and managing parallel changes to multiple resources.
  
       Configurations provide a mechanism for organizing resources and
       quick access to specific revisions of resources.  Clients can
       access resources in the context of a configuration.  By referencing
       a configuration, requests are automatically mapped to the correct
       revision of the versioned resource.  This allows configurations to
       be used as a reference mechanism without breaking URL hyperlinks.
  
       A configuration can be derived from another configuration.  That
       is, the new configuration is based on the versions in the "parent"
       configuration.  Optionally, derived configurations can
       automatically inherit new versions in the parent configuration
       (assuming there are no conflicts).  However, a configuration can be
       derived from at most one other configuration.
  
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       Clients can specify configuration ids wherever a revision id can be
       specified.  This requests that the default revision for the
       specified configuration be used.  Requests that include both a
       revision id and a configuration id MUST fail if the specified
       revision is not part of the specified configuration.  Typically
       both a revision id and a configuration id are not needed since the
       revision URI is unique across all configurations.
  
  
  6.1. Discovery
  
       Configuration support is optional.  This example shows that the
       /somefolder resource supports configurations.
  
       >> Request
  
       OPTIONS /somefolder/ HTTP/1.1
       Host: www.foobar.com
       Content-Length: xxx
       Content-Type: text/xml
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:options xmlns:D="DAV:">
          <D:verinfo/>
       </D:options>
  
       >> Response
  
       HTTP/1.1 200 OK
       Date: Tue, 20 Jan 1998 20:52:29 GMT
       Connection: close
       Accept-Ranges: none
       Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Public: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Versioning: DAV:basicversioning
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:options xmlns:D="DAV:">
          <D:verinfo>
            <D:configroot>
               <D:href>http://www.foobar.com/cfgs/</D:href>
            </D:configroot>
          </D:verinfo>
       </D:options>
  
  
  
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  6.2. Creating Configurations
  
       Servers maintain configurations in a private portion of the
       namespace.  The root of this namespace is determined by examining
       the OPTIONS extended reply.  All configurations names MUST be
       unique on a server.  Using the configuration namespace, clients can
       create and manage configurations.
  
       Clients create new configurations by issuing the MKCONFIG method
       against the configuration namespace.  This requests the server to
       create a new configuration.
  
       When a configuration is created, special tags can be used to define
       the characteristics and relationships (e.g. derivations) for the
       configuration.  The following table enumerates these tags.
  
  
                 Tag                  Description
  
  
            <DAV:configurationtype>   This tag defines the type
                                      of configuration:
                xxx                   DAV:Dynamic or
            </DAV:configurationtype>  DAV:Workspace.
  
  
  
            <DAV:derivedfrom>         This tag allows the client
            "xxx"                     to specify a URI to
            </DAV:derivedfrom>        identify another
                                      configuration from which
                                      this new configuration is
                                      to be derived.
  
  
            <DAV:inheritancetype>     The configuration
                                      automatically inherits
                DAV:Auto              changes from its derived-
            </DAV:inheritancetype>    from configuration.
                                      Conflicts are recorded in
                                      resolution queues (see
                                      later section).
  
  
            <DAV:inheritancetype>     The configuration inherits
                                      changes from its derived-
                DAV:Manual            from configuration, but
            </DAV:inheritancetype>    they are not automatically
                                      inserted into the
                                      configuration. Instead
                                      they are recorded in
                                      resolution queues (see
  
  
  
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                 Tag                  Description
  
  
                                      later section).
  
  
            <DAV:inheritancetype>
                                      snapshot of the current
                DAV:None              versions in the derived-
              DAV:inheritancetype>    from configuration.  There
                                      The configuration is a
                                      is no inheritance of
                                      changes.  This is the
                                      default type if no type is
                                      specified.
  
  
            <DAV:basetime>"xxx"       The configuration is based
            </DAV:basetime>           on the current versions in
                                      the derived-from
                                      configuration at the
                                      indicated time.  Note that
                                      use of this tag is
                                      incompatible with DAV:Auto
                                      inheritance types and
                                      usage in this way MUST
                                      return an error.
  
  
  
  
       When a non-derived configuration is created, it contains no
       resources.  Configurations that are derived from another
       configuration include the resources in the derived from
       configuration at the specified time or using the default revisions.
  
       The example below illustrates creating a new configuration that is
       derived from, and auto-inherits another configuration.  For this
       example, the root of the configuration namespace has been
       determined to be /cfgs.
  
       >>Request
  
       MKCONFIG /cfgs/ HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:createconfiguration xmlns:D="DAV:">
          <D:configurationtype>DAV:Workspace</D:configurationtype>
  
       <D:derivedfrom>http://www.foobar.com/cfgs/DDEJRJ445</D:derivedfrom>
          <D:inherit>Auto</D:inherit>
  
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       </D:createconfiguration>
  
       >>Response
  
       HTTP/1.1 201 Created
       Location: http://www.foobar.com/cfgs/RYURUS99009
       Content-Length: 0
  
  6.3. Access Using Configurations
  
       Configurations are maintained as a special collection.
       Configurations maintain referential members to all revisions that
       are part of the configuration.  Consequently, one approach to
       enumerating the contents of a configuration is to use PROPFIND to
       discover the contents of the collection.
  
       Alternatively, clients can request a specific resource from a
       configuration.  This approach allows clients to use the URL they
       are familiar with.  If a client requests a resource that is not
       part of a configuration, then an error is returned.
  
       >>Request
  
       GET /foo/bar.htm HTTP/1.1
       Host: www.foobar.com
       Configuration-Id: /cfgs/DFEE2034
       Content-Length: 0
  
  6.4. Deleting Configurations
  
       To delete a configuration, use the location returned from the
       configuration creation.  Note that configurations SHOULD NOT allow
       delete if other configurations are derived from them.
  
       >>Request
  
       DELETE /cfgs/RYURUS99009 HTTP/1.1
       Host: www.foobar.com
       Content-Length: 0
  
  6.5. Resolution Queues
  
       There are times when an operation cannot be blocked that will
       result in a state that requires user action.  For example, when
       configurations inherit, there is the potential for conflicts.
       Resolution queues provide a mechanism for discovering these
       conditions.
  
       Configurations track and maintain a list of issues that need to be
       resolved as a result of actions.  These lists are referred to as
       resolution queues.  Clients can request the resolution issues and
       react accordingly.  The configuration will continue to report the
       condition until it is resolved.
  
  
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       The resolution queue is obtained by obtaining the
       DAV:resolutionqueue property from the configuration.  This property
       contains all of the identified issues.
  
       >>Request
  
       PROPFIND /cfgs/FDJE4949 HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:prop>
            <D:resolutionqueue/>
          </D:prop>
       </D:propfind>
  
       >>Response
  
       HTTP/1.1 207 Multi-Status
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:multistatus xmlns:D="DAV:">
          <D:response>
            <D:href>http://www.foobar.com/cfgs/FDJE4949</D:href>
            <D:propstat>
               <D:prop>
                 <D:resolutionqueue>
                    <D:resolutionitem xmlns:D="DAV:">
                      <D:resolutiontype><D:conflict/></D:resolutiontype>
                      <D:resource>http:/foo/bar.htm</D:resource>
                      <D:newversion>DAV:FDFEE55544</D:newversion>
                    </D:resolutionitem>
                 </D:resolutionqueue>
               </D:prop>
            </D:propstat>
          </D:response>
       </D:multistatus>
  
       Once a client has resolved an issue it will automatically be
       removed from the resolution queue.
  
  
  6.6. Configuration Properties
  
       The standard PROPFIND and PROPPATCH methods can be used on the
       configuration resource to get and set properties on a
       configuration.  Configurations MUST provide configuration
       properties if configurations are supported.  The following list
       identifies pre-defined properties that MUST be supported:
  
  
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       DAV:configurationtype - The type of the configuration.
       Configurations can choose to make this a read-only property.
  
       DAV:derivedfrom - The configuration from which the configuration is
       derived.  Configurations can choose to make this a read-only
       property.
  
       DAV:inheritancetype - The type of inheritance for the
       configuration.  Configurations can choose to make this a read-only
       property.
  
       DAV:basetime - The base time used to create the configuration.
       Configurations can choose to make this a read-only property.
  
       DAV:defaultconfiguration - This property on the configuration root
       identifies the default workspace configuration to use if one is not
       specified.
  
       DAV:resolutionqueue - A list of identified issues that require
       client attention.
  
  
  6.7. Headers
  
       To support configurations, two new headers are introduced that can
       be used with a variety of the DAV and HTTP methods.  The following
       list identifies these headers:
  
       Configuration-Id - This header is used to identify the
       configuration that is to be used when performing an operation.
  
       For workspace configurations, this can be specified to set default
       revisions per-configuration, enumeration of checkouts/checkins
       against a specific configuration, or to establish locks specific to
       a configuration.
  
       If a configuration is not specified, the default workspace
       configuration is used.  All servers have a default workspace where
       resources reside.  The configuration "*" can be specified with
       PROPFIND to locate properties irrespective of configuration.
  
            Configuration-Id := "Configuration-Id" ":" (URL | "*")
  
       Note that the configuration id can be used in place of a revision
       id.  In this case, the revision selected is the default revision of
       the versioned resource within the specified configuration.
  
       Target-Configuration - This header is used to specify a target
       configuration when dealing with cross-configuration operations.
       For example, resources can be copied from one configuration to
       another using the Configuration-Id and Target-Configuration headers
       with the COPY method.  Note that resources CANNOT be MOVEd from one
       configuration to another.
  
  
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            Target-Configuration := "Target-Configuration" ":" URL
  
  7. CONFIGURATION REPORTS
  
       Revision history and configuration dependency graphs are accessed
       via PROPFIND.  Note that configurations MAY support multiple styles
       of history and dependency.  To enumerate the supported history
       graphs, clients use PROPFIND and the <DAV:availablereports>
       property.  The results indicate the different graphs and reports,
       which can, themselves, be requested via PROPFIND.
  
       >>Request
  
       PROPFIND /cfgs/FHJRH3994 HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:prop>
            <D:enumreport/>
          </D:prop>
       </D:propfind>
  
       >>Response
  
       ...
       <D:multistatus>
          <D:response>
            <D:href>http://www.foobar.com/cfgs/FHJRH3994</D:href>
            <D:propstat>
               <D:prop>
                 <D:enumreport>
                    <D:report>DAV:configurationderivation</D:report>
                    <D:report>DAV:configurationmerge</D:report>
                 </D:enumreport>
               </D:prop>
            </D:propstat>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
       ...
  
       When clients issue PROPFIND requests to obtain reports, they may
       include other properties in the request.  These properties are
       returned for each report item.
  
  
  7.1. Configuration Derivation
  
       Configurations MUST support the DAV:configurationderivation report.
       This enumerates the full derivation of a configuraiton.  Note that
  
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       the limit parameter can be specified to limit the number of items
       returned.  By definition the order of the configurations is
       immediate predecessor.
  
       >>Request
  
       PROPFIND /cfgs/BHFR59593 HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:configurationderivation limit=100/>
       </D:propfind>
  
       >>Response
  
       ...
       <D:multistatus>
          <D:response>
            <D:href>http:/www.foobar.com/cfgs/234</D:href>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http:/www.foobar.com/cfgs/345</D:href>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
       ...
  
  7.2. Configuration Merge Graph
  
       Configurations SHOULD support the DAV:configurationmerge report.
       This enumerates the derivation of a configuration including merges
       from one configuration to another.
  
       >>Request
  
       PROPFIND /cfgs/BHFR59593 HTTP/1.1
       Host: www.foobar.com
       Depth: 0
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:configurationmerge/>
       </D:propfind>
  
       >>Response
  
       ...
  
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       <D:multistatus>
          <D:response>
            <D:href>http:/www.foobar.com/cfgs/234</D:href>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
          <D:response>
            <D:href>http:/www.foobar.com/cfgs/3FF</D:href>
            <D:status>HTTP/1.1 200 OK</D:status>
          </D:response>
       </D:multistatus>
       ...
  
  8. DYNAMIC CONFIGURATIONS
  
       Dynamic configurations provide a mechanism to identify all
       revisions that match specific criteria.  For example, "all
       revisions that have the label Beta1".  The dynamic configuration is
       a view onto the resources and is updated automatically as resources
       and revisions are created, deleted, and modified.
  
       All dynamic configurations support the DAV:rsrtypes property.  This
       identifies the different styles of dynamic configurations to be
       supported.  This specification defines a single common type,
       DAV:basicrsr.
  
       >>Request
  
       PROPFIND /cfgs/FHHE49495 HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propfind xmlns:D="DAV:">
          <D:prop>
            <D:rsrtypes/>
          </D:prop>
       </D:propfind>
  
       >>Response
  
       HTTP/1.1 207 Multi-Status
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:multistatus xmlns:D="DAV:">
          <D:response>
            <D:href>http://www.foobar.com/cfgs/FHHE49495</D:href>
            <D:propstat>
               <D:prop>
                 <D:rsrtypes>
                    <D:basicrsr/>
                 </D:rsrtypes>
  
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               </D:prop>
            </D:propstat>
          </D:response>
       </D:multistatus>
  
       Clients establish a selection criteria by setting the
       DAV:selectionrule property.  Once set, the dynamic configuration
       collection contains references to the matching resources.
  
       >>Request
  
       PROPPATCH /cfgs/FHHE49495 HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:propertyupdate xmlns:D="DAV:">
          <D:set>
            <D:prop>
               <D:selectionrule>
                 <D:basicdynamicconfig>
                    ...
                 </D:basicdynamicconfig>
               </D:selectionrule>
            </D:prop>
          </D:set>
       </D:propertyupdate>
  
       The DAV:basicrsr tag groups the selection criteria that are used to
       populate the dynamic configuration.  The selection criteria is
       specified as a set of tags where nesting represents the
       expressional ordering.  The following tags are available:
  
       -  DAV:and - The included tags MUST all be true to select
  
       -  DAV:or - Any of the included tags MUST be true to select
  
       -  DAV:not - The include tag should be inverted (logically)
  
       -  DAV:href - The resource URL MUST be the included URL
  
       -  DAV:label - A revision MUST have the specified label
  
       -  DAV:tip - The "tip" revision is selected
  
       -  DAV:revisionid - The specified revision is selected
  
       -  DAV:configurationid - The configuration MUST be the specified
          value
  
       -  DAV:branchid - The branch MUST be the specified value
  
       -  DAV:depth - Used with DAV:href to indicate a recursive match
  
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       TBD - provide full DTD
  
       The following example illustrates a selection rule that includes
       all revisions in the /Foo/Bar folder (and below) that have been
       labeled as "Beta1".
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:basicrsr xmlns:D="DAV:">
          <D:and>
  
          <D:href>http:/www.foobar.com/Foo/Bar/<D:depth>infinity</D:depth><
       /D:href>
            <D:label>Beta1</D:label>
          </D:and>
       </D:basicrsr>
  
  9. WORKSPACE CONFIGURATIONS
  
       Branching provides a mechanism for parallel changes to a resource.
       A workspace configuration is a mechanism for parallel changes of
       multiple resources.
  
       For example, /MySite/ might contain all of the Web pages for V1 of
       my companies e-commerce site.   These have been put in the V1
       workspace.  A team responsible for developing V2 of the site would
       create a new workspace configuration based on V1.  The V2 workspace
       is populated with the V1 versions, but these resources can be
       versioned independently.  Essentially all resources have been
       "branched" in a coordinated fashion.  Since this is a branch, both
       the V1 and the V2 revisions refer to the same versioned resource.
       This allows history and reports to be generated across workspaces.
  
  
  9.1. Managing Configuration Content
  
       Clients need to be able to access and manage the contents of a
       configuration.  This is done using several different DAV methods.
  
       The COPY method  can be used to copy a specific revision of a
       resource.  However, this results in a new versioned resource being
       created.
  
       Resources are added to and removed from workspace configurations
       using the MKREF and DELREF methods defined by the DAV Advanced
       Collections Working Group.  Note that direct references are
       required.
  
       Clients can obtain the contents of a configuration using PROPFIND
       to enumerate the hierarchy under the configuation's collection.  As
       well, as stated above, clients can use the Configuration-Id header
       as described previously.
  
  
  
  
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  9.2. Default Workspace Configurations
  
       Clients can establish a default workspace configuration that is to
       be used, for all clients, if they do not specify a workspace
       configuration.  To do this, use the SETDEFAULT method against the
       configuration root identifying the default configuration.
  
       >>Request
  
       SETDEFAULT /cfgs/ HTTP/1.1
       Host: www.foobar.com
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:setdefault xmlns:D="DAV:">
          <D:href>http://www.foobar.com/cfgs/CHFH49594/</D:href>
       </D:setdefault>
  
       >>Response
  
       HTTP/1.1 200 OK
       Content-Length: 0
  
  10.  CHECKIN SETS
  
       Clients may desire the ability to track a set of changes as a unit.
       That is, create a grouping of related changes.  This is achieved
       using the MKCHECKINSET method to create a special collection.
       Clients refer to the checkin set on all checkin (or change)
       requests.  The server automatically creates a "share" to the newly
       created revision in the identified collection.
  
       Checkin sets are specific to a configuration and are created using
       the MKCHECKINSET method.  The DAV:checkinsetroot property on a
       configuration specifies the URL of a collection where checkin sets
       for the configuration exist.  This can be used for discovery or
       creation.  If a configuration doesn't support checkin sets, then
       this property will be empty.
  
       Clients create checkin sets using MKCHECKINSET.  The response
       includes the location of the new checkin set.
  
       >>Request
  
       MKCHECKINSET /cs/244 HTTP/1.1
       Host: www.foobar.com
       Content-Length: 0
  
       >>Response
  
       HTTP/1.1 201 CREATED
       Host: www.foobar.com
       Location: http://www.foobar.com/cs/244
  
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       Content-Length: 0
  
       The following example illustrates use of checkin sets.
  
       >>Request
  
       CHECKIN /foo/bar HTTP/1.1
       Host: www.foobar.com
       Lock-Token: <opaquelocktoken:rejrei-43343-rereffre>
       Checkin-Set: /cs/244
       Content-Type: text/html
       Content-Length: xxxx
  
       <D:checkin>
          ...
       </D:checkin>
  
       The following properties MUST be supported on all checkin set
       collections:
  
       DAV:closed - This is a true (1) / false (0) property that indicates
       if this checkin set can be referenced in CHECKIN requests.  When a
       checkin set is created, this property is defaulted to 0.  Note that
       resources MAY choose to disallow clients from setting this property
       to 0 once a client has set it to 1.
  
       The following properties MUST be supported on all resources:
  
       DAV:checkinid - This read-only property returns the checkin id
       associated with this revision of the resource.
  
       A checkin that references a checkin set MUST be made to the
       configuration associated with the checkin set.
  
  
  11.  VERSION MAPPING
  
       This specification defines headers to specify configurations and
       resource versions.  However, there are times when clients require a
       single URI for when working against configurations or versions.
       Version mapping support allows servers to create namespaces that
       map to configurations and versions.
  
       Note that mappings are dynamic.  That is, as resources are added,
       removed, and modified, the changes are reflected in any active
       maps.
  
       To delete a mapping, use DELETE against the URI specified in the
       MKMAP request.
  
  
  
  
  
  
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  11.1.     Discovery
  
       Mapping support is optional and support is discovered using OPTIONS
       to verify if the MKMAP method is supported.  Using the request body
       and the DAV:verinfo tag, clients can obtain the supported map
       styles.
  
        This example shows that the /cfgs/DFEE2034 configuration supports
       mapping to the /map/ root in the namespace.
  
       >> Request
  
       OPTIONS /cfgs/DFEE2034 HTTP/1.1
       Host: foobar.com
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:options xmlns:D="DAV:">
          <D:verinfo/>
       </D:options>
  
  
       >> Response
  
       HTTP/1.1 200 OK
       Date: Tue, 20 Jan 1998 20:52:29 GMT
       Connection: close
       Accept-Ranges: none
       Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Public: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
       MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKREF, FREEZE, THAW,
       CHECKIN,
       CHECKOUT, UNCHECKOUT, BRANCH
       Versioning: DAV:versioning
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:options xmlns:D="DAV:">
          <D:verinfo>
            <D:mapstyles>
               <D:mapstyle>DAV:detailedmap </D:mapstyle>
               <D:mapstyle>DAV:branchmap </D:mapstyle>
               <D:mapstyle>DAV:nestedbranch </D:mapstyle>
            </D:mapstyles>
          </D:verinfo>
       </D:options>
  
  
  
  
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  11.2.     Mapping Configurations
  
       The MKMAP method is used to create namespaces based on a
       configuration.  When a configuration is mapped to a new namespace,
       all elements within the configuration can be directly accessed
       within the namespace without requiring the configuration to be
       identified in the header.
  
       In the example below, a new namespace is created for accessing the
       contents of the /cfgs/DFEE2034 configuration.
  
       >> Request
  
       MKMAP /maps/mymap HTTP/1.1
       Host: foobar.com
       Configuration-Id: /cfgs/DFEE2034
       Content-Type: text/xml
       Content-Length: xxxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:configurationmap xmlns:D="DAV:"/>
  
  
       >> Response
  
       HTTP/1.1 201 CREATED
       Context-Length: 0
  
  11.3.     Mapping Resource Versions
  
       The MKMAP method is also used to create namespaces based on a
       resource's versions (i.e., its revision graph).  When a resource is
       mapped, its revision history (revision graph) within the
       configuration is made available without requiring the Revision-Id
       header.  Within the mapped namespace, a hierarchy is created for
       the revisions.
  
       However, there are different ways to map the history.  Consider the
       following revision history of the versioned resource bar.htm:
  
          V1 -> V2 -> V3       (primary branch)
           |
           +-> V1.1 -> V1.2    ("test" branch)
  
       The following diagrams illustrate possible mappings:
  
       (DAV:detailedmap)               (DAV:branchmap)
       (DAV:nestedbranchmap)
  
        V1                          Primary  Test           Primary
        |                              |       |               |
        +----+--------+                V1     V1.1             +------ Test
  
  
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  INTERNET-DRAFT        WebDAV Versioning     January 20, 1999
  
  
        |    |        |                |       |               |         |
        V2   bar.htm  V1.1             V2     V1.2             V1       V1.1
        |             |                |                       |         |
        +----+        +-----+          V3                      V2       V1.2
        |    |        |     |                                  |
        V3   bar.htm  V1.2  bar.htm                            V3
        |             |
        bar.htm       bar.htm
  
  
       In the example below, a new namespace is created for accessing the
       versions of the /foo/bar.htm resource in the /cfgs/DFEE2034
       configuration.
  
       >> Request
  
       MKMAP /maps/mymap2 HTTP/1.1
       Host: foobar.com
       Configuration-Id: /cfgs/DFEE2034
       Content-Type: text/xml
       Content-Length: xxx
  
       <?xml version="1.0" encoding="utf-8" ?>
       <D:revisionmap xmlns:D="DAV:">
          <D:href>/foo/bar.htm</D:href>
          <D:mapstyle>DAV:detailedmap</D:mapstyle>
       </D:revisionmap>
  
  
       >> Response
  
       HTTP/1.1 201 CREATED
       Context-Length: 0
  
       Note that resources MAY support any mapping styles, however, if
       they support MKMAP, then it MUST support DAV:detailedmap as
       illustrated above.
  
  
  12.  THE DAV VERSIONING GRAMMAR
  
       To be supplied - Describe and detail the DTDs
  
  
  13.  INTERNATIONALIZATION CONSIDERATIONS
  
       To be supplied.
  
  
  
  
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  INTERNET-DRAFT        WebDAV Versioning     January 20, 1999
  
  
  14.  SECURITY CONSIDERATIONS
  
       To be supplied.
  
  
  15.  SCALABILITY
  
       To be supplied.
  
  
  16.  AUTHENTICATION
  
       Authentication mechanisms defined in WebDAV will also apply to DAV
       Versioning.
  
  
  17.  IANA CONSIDERATIONS
  
       This document uses the namespace defined by [WebDAV] for XML
       elements.  All other IANA considerations mentioned in [WebDAV] also
       applicable to DAV Versioning.
  
  
  18.  COPYRIGHT
  
       To be supplied.
  
  
  19.  INTELLECTUAL PROPERTY
  
       To be supplied.
  
  
  20.  REFERENCES
  
       [DAVVERREQ] TBD, "Requirements for DAV Versioning and Variant
       Authoring", October 1998, internet-draft, work-in-progress, draft-
       ietf-webdav-versionreqs-00.txt
  
       [Kaler] C. Kaler, "Versioning Extensions for WebDAV", September
       1998, internet-draft, work-in-progress, draft-kaler-webdav-
       versioning-00.
  
       [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, January 1997.
  
       [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
       Requirement Levels." RFC 2119, BCP 14. Harvard University. March,
       1997.
  
       [WebDAV] Y. Goland, E.J. Whitehead, A. Faizi, S.R. Carter, D.
       Jenson, "Extensions for Distributed Authoring on the World Wide
  
  
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  INTERNET-DRAFT        WebDAV Versioning     January 20, 1999
  
  
       Web", April. 1998, internet-draft, work-in-progress, draft-ietf-
       webdav-protocol-08.
  
       [White] E.J. Whitehead, "A Web Versioning Protocol", June 1998,
       internet-draft, work-in-progress, draft-whitehead-webdav-
       versioning-00.
  
  
  21.  AUTHOR'S ADDRESSES
  
       Christopher Kaler, Editor
       Microsoft
       One Microsoft Way
       Redmond WA, 9085-6933
       Email:ckaler@microsoft.com
  
       Jim Amsden
       IBM
       Email: jamsden@us.ibm.com
  
       Geoff Clemm
       Rational
       Email: gclemm@atria.com
  
       Bruce Cragun
       Novell Inc.
       1555 N. Technology Way
       Orem, UT 84097
       Email: bcragun@novell.com
  
       David Durand
       Email: dgd@cs.bu.edu
  
       Bradley Sergeant
       MicroFocus
       Email: bradley_sergeant@intersolv.com
  
       E. James Whitehead, Jr.
       Dept. of Information and Computer Science
       University of California, Irvine
       Irvine, CA 92697-3425
       Email: ejw@ics.uci.edu
  
  
  22.  OPEN ISSUES
  
       The following list identifies key open issues against this
       document:
  
       .  Can you checkout a collection?  What does it mean?
  
       .  What tags do we want to use for resource/configuration report
          results?
  
  
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  INTERNET-DRAFT        WebDAV Versioning     January 20, 1999
  
  
       .  What structure do we create for maps?
  
       .  What additional resource branching support is needed?
  
       .  Schema discovery is an issue.  For example, how to
          discover/change mutable/immutable properties?
  
       .  There are several missing examples / replies that need to be
          specified.
  
  
  23.  CHANGE HISTORY
  
  
       Sep 28, 1998
  
       Initial Draft based on [White] and [Kaler].
  
  
       Oct 24, 1998
  
       Incorporate feedback from October 01-02 working group meeting.
  
  
       Jan 20, 1999
  
       Incorporate feedback from December 1998 working group meeting.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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