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RE: Feature request for CHECKIN/OUT extension

From: Julian F. Reschke <julian.reschke@greenbytes.de>
Date: Sun, 9 Sep 2001 19:50:24 +0200
To: "Julian F. Reschke" <julian.reschke@greenbytes.de>, <ietf-dav-versioning@w3.org>
Message-ID: <JIEGINCHMLABHJBIGKBCCEJGDAAA.julian.reschke@greenbytes.de>
Attached is an ID-formatted version of my proposal (below in text format,
attached as RFC2629-XML).

--


Network Working Group                                         J. Reschke
Internet-Draft                                                greenbytes
Expires: March 10, 2002                                September 9, 2001


             Computing the CHECKIN URI in WebDAV versioning
               draft-reschke-deltav-computecheckinuri-00

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on March 10, 2002.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   In many cases, a versioning-aware client might want to
   display/include the URI of the version it's editing while it's being
   edited.  For instance, an editor might include this as meta
   information, or the author of a document might want to know the URI
   of the version before it's checked in.  A well-known example is the
   W3C way of referring to document versions in recommendations: it
   contains references to "the current version", to "this version" and
   to the "previous version".  Something like this is currently
   impossible with the current draft version of WebDAV deltaV [deltaV],
   as the version URI is determined at the time of CHECKIN.

   Distribution of this document is unlimited.  Please send comments to



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   the WebDAV versioning (delta-V) working group at ietf-dav-
   versioning@w3.org[1], which may be joined by sending a message with
   subject "subscribe" to ietf-dav-versioning-request@w3.org[2].

   Discussions of the delta-V working group are archived at URL:
   http://lists.w3.org/Archives/Public/ietf-dav-versioning/.

Table of Contents

   1.  Notational Conventions . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Changes for CHECKOUT method (when applied to a
       version-controlled resource) . . . . . . . . . . . . . . . . .  5
   3.1 Example for successful CHECKOUT with computed-checkin-URI  . .  5
   3.2 Example for successful CHECKOUT without computed-checkin-URI .  6
   4.  Changes for CHECKIN method (when applied to a
       version-controlled resource) . . . . . . . . . . . . . . . . .  7
   4.1 Example for successful CHECKIN with computed-checkin-URI . . .  7
   4.2 Example for failed CHECKIN with computed-checkin-URI . . . . .  8
   5.  Compatibility Considerations . . . . . . . . . . . . . . . . .  9
   6.  Internationalization Considerations  . . . . . . . . . . . . . 10
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   8.  Copyright  . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   9.  Intellectual Property  . . . . . . . . . . . . . . . . . . . . 13
       References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 14
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 15
























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1. Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].














































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2. Introduction

   In many cases, a versioning-aware client might want to
   display/include the URI of the version it's editing while it's being
   edited.  For instance, an editor might include this as meta
   information, or the author of a document might want to know the URI
   of the version before it's checked in.  A well-known example is the
   W3C way of referring to document versions in recommendations: it
   contains references to "the current version", to "this version" and
   to the "previous version".  Something like this is currently
   impossible with the current draft version of WebDAV deltaV [deltaV],
   as the version URI is determined at the time of CHECKIN.

   This specification builds on the infrastructure provided by the
   WebDAV Versioning Protocol, adding support for servers willing to
   compute an "expected CHECKIN URI" upon CHECKOUT, and using this URI
   at time of CHECKIN.


































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3. Changes for CHECKOUT method (when applied to a version-controlled
   resource)

   A client may ask for an "expected CHECKIN URI" upon CHECKOUT.  This
   is done by placing DAV:compute-expected-checkin-URI as top-level
   element into the request body.  The server is free to either ignore
   the request, or to return it's best guess about what the URI for a
   version resource created upon CHECKIN would be.

   The client can detect the "expected CHECKIN URI" by parsing the
   response body for a top-level element called DAV:expected-checkin-
   URI.

3.1 Example for successful CHECKOUT with computed-checkin-URI

    >>Request

      CHECKOUT /foo.html HTTP/1.1
      Host: www.webdav.org
      Content-Type: text/xml; charset="utf-8"
      Content-Length: xxxx

      <D:checkout xmlns:D="DAV:">
        <D:compute-expected-version-URI />
      </D:checkout>

    >>Response

      HTTP/1.1 200 OK
      Cache-Control: no-cache
      Content-Type: text/xml; charset="utf-8"
      Content-Length: xxxx

      <D:checkout-response xmlns:D="DAV:">

<D:expected-version-URI>http://repo.webdav.org/his/23/ver/32</D:expected-ver
sion-URI>
      </D:checkout-response>

   In this example, the server was able to compute the "expected CHECKIN
   URI" and returned it in the DAV:expected-version-URI element.












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3.2 Example for successful CHECKOUT without computed-checkin-URI

    >>Request

      CHECKOUT /foo.html HTTP/1.1
      Host: www.webdav.org
      Content-Type: text/xml; charset="utf-8"
      Content-Length: xxxx

      <D:checkout xmlns:D="DAV:">
        <D:compute-expected-version-URI />
      </D:checkout>

    >>Response

      HTTP/1.1 200 OK
      Cache-Control: no-cache

   In this case, no response body was returned, and thus no "expected
   CHECKIN URI" is available.  Simarily, the server may also return

    >>Response

      HTTP/1.1 200 OK
      Cache-Control: no-cache
      Content-Type: text/xml; charset="utf-8"
      Content-Length: xxxx

      <D:checkout-response xmlns:D="DAV:">
          ...other content...
      </D:checkout-response>

   where a response body is available, but it doesn't contain the
   DAV:expected-checkin-URI element.

















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4. Changes for CHECKIN method (when applied to a version-controlled
   resource)

   A client may submit the "expected CHECKIN URI" (obtained during
   CHECKOUT) upon a CHECKIN by placing it into a top-level DAV:expected-
   checkin-URI element in the request body.  A server may

   o  simply ignore the presence of this information or

   o  use the information and try to checkin the resource using the
      "expected checkin URI" as location for the version resource.  A
      failure to create a version resource at the "expected checkin URI"
      MUST cause the operation to fail with a status code of 403
      (forbidden) and a response body containing the top-level element
      DAV:cannot-assign-expected-version-URI.  In addition, a server MAY
      return a new "expected checkin URI" in it's response body.


4.1 Example for successful CHECKIN with computed-checkin-URI

   >>Request

     CHECKIN /foo.html HTTP/1.1
     Host: www.webdav.org
     Content-Type: text/xml; charset="utf-8"
     Content-Length: xxxx

     <D:checkin xmlns:D="DAV:">

<D:expected-version-URI>http://repo.webdav.org/his/23/ver/32</D:expected-ver
sion-URI>
     </D:checkin>

    >>Response

     HTTP/1.1 201 Created
     Location: http://repo.webdav.org/his/23/ver/32
     Cache-Control: no-cache















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4.2 Example for failed CHECKIN with computed-checkin-URI

    >>Request

     CHECKIN /foo.html HTTP/1.1
     Host: www.webdav.org
     Content-Type: text/xml; charset="utf-8"
     Content-Length: xxxx

     <D:checkin xmlns:D="DAV:">

<D:expected-version-URI>http://repo.webdav.org/his/23/ver/32</D:expected-ver
sion-URI>
     </D:checkin>

    >>Response

     HTTP/1.1 403 Forbidden
     Cache-Control: no-cache
     Content-Type: text/xml; charset="utf-8"
     Content-Length: xxxx

     <D:checkin-response xmlns:D="DAV:">
       <D:cannot-assign-expected-version-URI />

<D:expected-version-URI>http://repo.webdav.org/his/23/ver/33</D:expected-ver
sion-URI>
     </D:checkin-response>



























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5. Compatibility Considerations

   This specification does introduce new protocol elements for the
   request and response bodies for CHECKIN and CHECKOUT.

   Clients not aware of this specification will never submit the new
   protocol elements in a request and therefore never will see the new
   response elements.

   Servers not aware of this specification will ignore the additional
   two request body elements which is legal behaviour according to this
   protocol (indicating that the protocol extension is not available).







































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6. Internationalization Considerations

   This proposal builds on [deltaV], and inherits its
   internationalizability.















































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7. IANA Considerations

   This proposal does not introduce any new IANA considerations, since
   it does not specify any new namespaces (in the general sense), but
   merely uses existing ones.














































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8. Copyright

   To be supplied by the RFC Editor.
















































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9. Intellectual Property

   To be supplied by the RFC Editor.
















































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References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2518]  Goland, Y., Whitehead, E., Faizi, A., Carter, S. and D.
              Jensen, "HTTP Extensions for Distributed Authoring --
              WEBDAV", RFC 2518, February 1999.

   [deltaV]   Clemm, G., Amsden, J., Ellison, T., Kaler, C. and J.
              Whitehead, "Versioning Extensions to WebDAV", ID draft-
              ietf-deltav-versioning-17, August 2001,
              <http://www.webdav.org/deltav/protocol/draft-ietf-deltav-
              versioning-17.htm>.

   [1]  <mailto:ietf-dav-versioning@w3.org>

   [2]  <mailto:ietf-dav-versioning-request@w3.org?subject=subscribe>


Author's Address

   Julian F. Reschke
   greenbytes GmbH
   Salzmannstrasse 152
   Muenster, NW  48159
   Germany

   EMail: julian.reschke@greenbytes.de






















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Full Copyright Statement

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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> -----Original Message-----
> From: ietf-dav-versioning-request@w3.org
> [mailto:ietf-dav-versioning-request@w3.org]On Behalf Of Julian F.
> Reschke
> Sent: Friday, September 07, 2001 9:23 PM
> To: ietf-dav-versioning@w3.org
> Subject: Re: Feature request for CHECKIN/OUT extension
>
>
> Hi,
>
> I have updated my proposal. The main changes are:
>
> 1) I am now using the defined element names for the response bodies
> (checkin-response, checkout-response) [Geoff, thanks for adding this to
> draft 17]
>
> 2) FORBIDDEN is 403, not 409.
>
> Julian
>
> --
>
> Feature request for CHECKIN/OUT extension
>
> In many cases, a versioning-aware client might want to display/include the
> URI of the version it's editing *while* it's edited. For instance, a
> versioning
> aware editor might include this as meta-information, or the author of a
> document might want to know the URI of the version *before* it's
> checked in.
> A well-known example is the W3C way of referring to document versions in
> recommendations: it contains HREFs to "the current version", to "this
> version"
> and to the "previous version". Something like this is currently impossible
> with deltaV, as the version URI is determined at the time of CHECKIN.
>
> Proposal:
>
> 1) Extend CHECKOUT to optionally return an "expected CHECKIN URI".
> 2) Extend CHECKIN to optionally use the "expected CHECKIN URI",
> failing the
> request if it's not possible to checkin the resource with the desired
> version URI (in which case a new "expected CHECKIN URI" is returned).
>
>
> I propose to pass the information in the request/response bodies of
> CHECKIN / CHECKOUT, such as:
>
> CHECKOUT method:
>
> >>REQUEST
>
>   CHECKOUT /foo.html HTTP/1.1
>   Host: www.webdav.org
>   Content-Type: text/xml; charset="utf-8"
>   Content-Length: xxxx
>
>   <D:checkout xmlns:D="DAV:">
>     <D:compute-expected-version-URI />
>   </D:checkout>
>
>
> >>RESPONSE
>
>   HTTP/1.1 200 OK
>   Cache-Control: no-cache
>   Content-Type: text/xml; charset="utf-8"
>   Content-Length: xxxx
>
>   <D:checkout-response xmlns:D="DAV:">
>
> <D:expected-version-URI>http://repo.webdav.org/his/23/ver/32</D:ex
> pected-ver
> sion-URI>
>   </D:checkout-response>
>
> (Note: if the expected-version-URI cannot be computed, the server will
> simply not
> include it in it's answer).
>
>
> CHECKIN method:
>
>
> >>REQUEST
>
>   CHECKIN /foo.html HTTP/1.1
>   Host: www.webdav.org
>   Content-Type: text/xml; charset="utf-8"
>   Content-Length: xxxx
>
>   <D:checkin xmlns:D="DAV:">
>
> <D:expected-version-URI>http://repo.webdav.org/his/23/ver/32</D:ex
> pected-ver
> sion-URI>
>   </D:checkin>
>
> >>RESPONSE
>
>   HTTP/1.1 201 Created
>   Location: http://repo.webdav.org/his/23/ver/32
>   Cache-Control: no-cache
>
>   or
>
> >>RESPONSE
>
>   HTTP/1.1 403 Forbidden
>   Cache-Control: no-cache
>   Content-Type: text/xml; charset="utf-8"
>   Content-Length: xxxx
>
>   <D:checkin-response xmlns:D="DAV:">
>     <D:cannot-assign-expected-version-URI />
>
> <D:expected-version-URI>http://repo.webdav.org/his/23/ver/33</D:ex
> pected-ver
> sion-URI>
>   </D:checkin-response>
>
>



Received on Sunday, 9 September 2001 13:50:56 GMT

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