[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 RFC 5829

Network Working Group                                           A. Brown
Internet-Draft                                                  G. Clemm
Intended status: Informational                                       IBM
Expires: May 24, 2010                                    J. Reschke, Ed.
                                                              greenbytes
                                                       November 20, 2009


              Link Relations for Simple Version Navigation
                draft-brown-versioning-link-relations-03

Abstract

   This specification defines Atom link relations for navigation between
   a resource and its versions.

Editorial Note (To be removed by RFC Editor before publication)

   Please send comments to the Atom Syntax mailing list
   (<http://www.imc.org/atom-syntax/>).

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   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.

   This Internet-Draft will expire on May 24, 2010.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



Brown, et al.             Expires May 24, 2010                  [Page 1]


Internet-Draft      Version Navigation Link Relations      November 2009


   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Link Relations . . . . . . . . . . . . . . . . . . . . . . . .  3
     3.1.  version-history  . . . . . . . . . . . . . . . . . . . . .  3
     3.2.  latest-version . . . . . . . . . . . . . . . . . . . . . .  4
     3.3.  working-copy . . . . . . . . . . . . . . . . . . . . . . .  4
     3.4.  predecessor-version  . . . . . . . . . . . . . . . . . . .  4
     3.5.  successor-version  . . . . . . . . . . . . . . . . . . . .  4
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  'version-history' Link Relation Registration . . . . . . .  4
     4.2.  'latest-version' Link Relation Registration  . . . . . . .  5
     4.3.  'working-copy' Link Relation Registration  . . . . . . . .  5
     4.4.  'predecessor-version' Link Relation Registration . . . . .  5
     4.5.  'successor-version' Link Relation Registration . . . . . .  6
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  6
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     6.1.  Normative References . . . . . . . . . . . . . . . . . . .  6
     6.2.  Informative References . . . . . . . . . . . . . . . . . .  6
   Appendix A.  Relationship to Java Content Repository (JCR) and
                WebDAV  . . . . . . . . . . . . . . . . . . . . . . .  7
     A.1.  Example: Use of Link Relations in HTTP Link Header . . . .  8
   Appendix B.  Contributors  . . . . . . . . . . . . . . . . . . . .  9
   Appendix C.  Change Log (to be removed by RFC Editor before
                publication)  . . . . . . . . . . . . . . . . . . . .  9
     C.1.  Since draft-brown-link-relations-00  . . . . . . . . . . .  9
     C.2.  Since draft-brown-link-relations-01  . . . . . . . . . . . 10
     C.3.  Since draft-brown-link-relations-02  . . . . . . . . . . . 10
   Appendix D.  Resolved issues (to be removed by RFC Editor
                before publication) . . . . . . . . . . . . . . . . . 10
     D.1.  iana . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   Appendix E.  Open issues (to be removed by RFC Editor prior to
                publication)  . . . . . . . . . . . . . . . . . . . . 10
     E.1.  edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10




Brown, et al.             Expires May 24, 2010                  [Page 2]


Internet-Draft      Version Navigation Link Relations      November 2009


1.  Introduction

   This specification defines link relations that may be used on a
   resource that exists in a system that supports versioning to navigate
   among the different resources available, such as past versions.


2.  Terminology

   Versioned Resource

      When a resource is put under version control, it becomes a
      "versioned resource".  A versioned resource can be "checked out"
      to allow modification.

   Version History

      A "version history" resource is a resource that contains all the
      versions of a particular versioned resource.

   Predecessor, Successor

      When a versioned resource is checked out and then subsequently
      checked in, the version that was checked out becomes a
      "predecessor" of the version created by the checkin.  A client can
      specify multiple predecessors for a new version if the new version
      is logically a merge of those predecessors.  The inverse of the
      predecessor relation is the "successor" relation.  Therefore, if X
      is a predecessor of Y, then Y is a successor of X.

   Working Copy

      A "working copy" is a resource at a server-defined URL that can be
      modified to create a new version of a versioned resource.


3.  Link Relations

   The following link relations are defined:

3.1.  version-history

   When included on a versioned resource, this link points to a resource
   containing the version history for this resource.







Brown, et al.             Expires May 24, 2010                  [Page 3]


Internet-Draft      Version Navigation Link Relations      November 2009


3.2.  latest-version

   When included on a versioned resource, this link points to a resource
   containing the latest (e.g., current) version.

   The latest version is defined by the system.  For linear versioning
   systems, this is probably the latest version by timestamp.  For
   systems that support branching, there will be multiple latest
   versions, one for each branch in the version history.

   Some systems may allow multiple of these link relations.

3.3.  working-copy

   When included on a versioned resource, this link points to a working
   copy for this resource.

   Some systems may allow multiple of these link relations.

3.4.  predecessor-version

   When included on a versioned resource, this link points to a resource
   containing the predecessor version in the version history.

   Some systems may allow multiple of these link relations in the case
   of a multiple branches merging.

3.5.  successor-version

   When included on a versioned resource, this link points to a resource
   containing the successor version in the version history.

   Some systems may allow multiple of these link relations in order to
   support branching.


4.  IANA Considerations

   The link relations below are to be registered by IANA per Section 7.1
   of [RFC4287]:

4.1.  'version-history' Link Relation Registration

   Attribute Value:  version-history







Brown, et al.             Expires May 24, 2010                  [Page 4]


Internet-Draft      Version Navigation Link Relations      November 2009


   Description:  See Section 3.1.

   Expected display characteristics:  Undefined; this relation can be
      used for background processing or to provide extended
      functionality without displaying its value.

   Security considerations:  See Section 5.

4.2.  'latest-version' Link Relation Registration

   Attribute Value:  latest-version

   Description:  See Section 3.2.

   Expected display characteristics:  Undefined; this relation can be
      used for background processing or to provide extended
      functionality without displaying its value.

   Security considerations:  See Section 5.

4.3.  'working-copy' Link Relation Registration

   Attribute Value:  working-copy

   Description:  See Section 3.3.

   Expected display characteristics:  Undefined; this relation can be
      used for background processing or to provide extended
      functionality without displaying its value.

   Security considerations:  See Section 5.

4.4.  'predecessor-version' Link Relation Registration

   Attribute Value:  predecessor-version

   Description:  See Section 3.4.

   Expected display characteristics:  Undefined; this relation can be
      used for background processing or to provide extended
      functionality without displaying its value.

   Security considerations:  See Section 5.








Brown, et al.             Expires May 24, 2010                  [Page 5]


Internet-Draft      Version Navigation Link Relations      November 2009


4.5.  'successor-version' Link Relation Registration

   Attribute Value:  successor-version

   Description:  See Section 3.5.

   Expected display characteristics:  Undefined; this relation can be
      used for background processing or to provide extended
      functionality without displaying its value.

   Security considerations:  See Section 5.


5.  Security Considerations

   Automated agents should take care when these relation crosses
   administrative domains (e.g., the URI has a different authority than
   the current document).  Such agents should also take care to detect
   circular references.


6.  References

6.1.  Normative References

   [RFC4287]  Nottingham, M. and R. Sayre, "The Atom Syndication
              Format", RFC 4287, December 2005.

6.2.  Informative References

   [JSR-283]  Day Software, Nuescheler, D., and P. Piegaze, "Content
              Repository API for Java[TM] Technology Specification",
              Java Specification Request 283, August 2009,
              <http://www.day.com/specs/jcr/2.0/>.

   [RFC3253]  Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J.
              Whitehead, "Versioning Extensions to WebDAV (Web
              Distributed Authoring and Versioning)", RFC 3253,
              March 2002.

   [draft-nottingham-http-link-header]
              Nottingham, M., "Web Linking",
              draft-nottingham-http-link-header-06 (work in progress),
              July 2009.







Brown, et al.             Expires May 24, 2010                  [Page 6]


Internet-Draft      Version Navigation Link Relations      November 2009


Appendix A.  Relationship to Java Content Repository (JCR) and WebDAV

   The link relations defined in Section 3 correspond to various
   properties used in WebDAV Versioning [RFC3253] and JCR [JSR-283]:

   version-history

      WebDAV: the resource identified by the DAV:version-history
      property ([RFC3253], Sections 5.2.1 and 5.3.1).

      JCR: the node identified by jcr:versionHistory property
      ([JSR-283], Section 3.13.2.4) for versionable nodes, the parent
      folder for version nodes.

   latest-version

      WebDAV: for version-controlled resources, DAV:checked-in
      ([RFC3253], Section 3.2.1) or DAV:checked-out ([RFC3253], Section
      3.3.1), depending on checkin state.  For version resources, a
      successor version that itself does not have any successors.

      JCR: the version node identified by the jcr:baseVersion property
      ([JSR-283], Section 3.13.2.5) for versionable nodes; for version
      nodes, a successor version that itself does not have any
      successors.

   working-resource

      WebDAV: for version-controlled resources that are checked-out in
      place: the resource itself.  For version resources: each resource
      identified by a member of the DAV:checkout-set property (see
      [RFC3253], Section 3.4.3).

      JCR: for checked-out versionable nodes: the node itself.

   predecessor-version

      WebDAV: each resource identified by a member of DAV:predecessor-
      set ([RFC3253], Sections 3.3.2 and 3.4.1).

      JCR: each node identified by a member of jcr:predecessors
      ([JSR-283], Section 3.13.3.3).

   successor-version

      WebDAV: each resource identified by a member of DAV:successor-set
      ([RFC3253], Section 3.4.2).




Brown, et al.             Expires May 24, 2010                  [Page 7]


Internet-Draft      Version Navigation Link Relations      November 2009


      JCR: each node identified by a member of jcr:successors
      ([JSR-283], Section 3.13.3.4).

A.1.  Example: Use of Link Relations in HTTP Link Header

   The "Web Linking" specification ([draft-nottingham-http-link-header])
   generalizes Atom link relations, and also re-introduces the HTTP
   "Link" header as a way to expose link relations in HTTP responses.
   This will make it possible to expose version links independently from
   a specific vocabulary, be it the Atom Feed Format ([RFC4287]) or
   WebDAV properties ([RFC3253]).

   For instance, a response to an VERSION-CONTROL request ([RFC3253],
   Section 3.5) could expose newly created version-history and
   checked-in version as link relations:

   >> Request:


   VERSION-CONTROL /docs/test.txt HTTP/1.1
   Host: example.net


   >> Response:


   HTTP/1.1 200 OK
   Link: </system/v/84345634/1>; rel=latest-version;
         anchor=</docs/test.txt>
   Link: </system/vh/84345634>; rel=version-history;
         anchor=</docs/test.txt>


   (Note that in this case, the anchor parameter is used, as the
   response to a VERSION-CONTROL request is not a representation of the
   resource at the Request-URI)

   A subsequent HEAD request on that resource could expose the version-
   history and latest-version relations as well:

   >> Request:


   HEAD /docs/test.txt HTTP/1.1
   Host: example.net






Brown, et al.             Expires May 24, 2010                  [Page 8]


Internet-Draft      Version Navigation Link Relations      November 2009


   >> Response:


   HTTP/1.1 200 OK
   Content-Type: text/plain; charset=UTF-8
   Content-Length: 12345
   Link: </system/v/84345634/1>; rel=latest-version
   Link: </system/vh/84345634>; rel=version-history


   After creating more versions, following the latest-version would then
   expose predecessors of a version:

   >> Request:


   HEAD /system/v/84345634/3 HTTP/1.1
   Host: example.net


   >> Response:


   HTTP/1.1 200 OK
   Content-Type: text/plain; charset=UTF-8
   Content-Length: 12323
   Link: </system/v/84345634/2>; rel=predecessor-version



Appendix B.  Contributors

   The content and concepts within are a product of the Content
   Management Interoperability Services (CMIS) Technical Committee (TC)
   at OASIS.

   All members of the TC have contributed.


Appendix C.  Change Log (to be removed by RFC Editor before publication)

C.1.  Since draft-brown-link-relations-00

   Added Geoff Clemm as author.

   Renamed link relation "all-versions" to "version-history".  Fixed
   description of "working-resource" relation to state that it appears
   on a version resource.



Brown, et al.             Expires May 24, 2010                  [Page 9]


Internet-Draft      Version Navigation Link Relations      November 2009


C.2.  Since draft-brown-link-relations-01

   Rewrite terminology and link relations using simpler definitions that
   can reflect versioning approaches different from WebDAV.

   Add JCR/WebDAV property table.  And reference to Web Linking draft
   (for now informative) and examples showing use of the Link header.

C.3.  Since draft-brown-link-relations-02

   Add and resolve issue "iana".


Appendix D.  Resolved issues (to be removed by RFC Editor before
             publication)

   Issues that were either rejected or resolved in this version of this
   document.

D.1.  iana

   Type: change

   julian.reschke@greenbytes.de (2009-11-20): Use proper IANA
   registration template.


Appendix E.  Open issues (to be removed by RFC Editor prior to
             publication)

E.1.  edit

   Type: edit

   julian.reschke@greenbytes.de (2009-11-19): Umbrella issue for
   editorial fixes/enhancements.


Authors' Addresses

   Al Brown
   IBM
   3565 Harbor Blvd
   Costa Mesa, California  92626
   US

   Email: albertcbrown@us.ibm.com




Brown, et al.             Expires May 24, 2010                 [Page 10]


Internet-Draft      Version Navigation Link Relations      November 2009


   Geoffrey Clemm
   IBM
   20 Maguire Road
   Lexington, MA  02421
   US

   Email: geoffrey.clemm@us.ibm.com


   Julian F. Reschke (editor)
   greenbytes GmbH
   Hafenweg 16
   Muenster, NW  48155
   Germany

   Email: julian.reschke@greenbytes.de
   URI:   http://greenbytes.de/tech/webdav/


































Brown, et al.             Expires May 24, 2010                 [Page 11]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/