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RE: XML in LOCK <owner> tag should be self-contained

From: Julian Reschke <julian.reschke@gmx.de>
Date: Fri, 20 Sep 2002 19:12:21 +0200
To: "John Spaith" <jspaith@windows.microsoft.com>, <w3c-dist-auth@w3.org>
Message-ID: <JIEGINCHMLABHJBIGKBCCEFBFGAA.julian.reschke@gmx.de>
MessageI think this is identical to the problem of how faithfully the
namespace prefixes are preserved inside dead properties.

IMHO

- namespace information must be preserved (hopefully this is obvious)
- namespace prefixes on elements *inside* prooerty values should be
preserved
- namespace declarations that are needed but appeared outside the actual
property may be returned anywhere recreating the correct scope

This should then also apply the content of the DAV:owner element.

Julian
--
<green/>bytes GmbH -- http://www.greenbytes.de -- tel:+492512807760

  -----Original Message-----
  From: w3c-dist-auth-request@w3.org [mailto:w3c-dist-auth-request@w3.org]On
Behalf Of John Spaith
  Sent: Friday, September 20, 2002 5:57 PM
  To: w3c-dist-auth@w3.org
  Subject: XML in LOCK <owner> tag should be self-contained


  Ladies and Gentleman,

  At the WebDAV interop fest, we saw that some servers weren't doing the
right thing when clients send them <owner> tags on a LOCK request.  When
doing a LOCK a client can put in XML in the owner tag, and this XML often
times has namespaces prefixes in it.  So we have something like...

  LOCK

  <xml>
   <lockinfo xmlns:MyNS="MyNameSpace">
    [...]
     <owner>
        <MyNS:MyTag>...</MyNS:MyTag>
     </owner>
    [...]

  When the server returns this owner tag on a lockdiscovery, it has to also
return the definition of the MyNS namespace in the <owner> tags or clients
will choke on not recognizing MyNS prefix.  Having to keep track of prefix
mappings when parsing the LOCK body is an added piece of complexity that
servers don't really need.  It would be better if we could require (or more
likely strongly encourage) clients to make any XML inside the <owner> tag
work standalone, i.e. forcing them to define any namespaces they use there.
They would send something like this on a LOCK.

   <owner>
     <MyNS:MyTag xmlns:MyNS="MyNameSpace">...</MyNS:MyTag>
   </owner>

  This way the server could just keep a copy of the data between the <owner>
tags without any extra processing.

  Steps to increase interop:
  1. Server implementers should be aware of this and code accordingly.  A
number of servers at the WebDAV interop fest only copied the data between
<owner> tags, not doing the extra name space processing.

  2. We should say something to the effect that clients SHOULD send
self-contained XML data with all the namespaces prefixes they used defined
between the <owner> tags to workaround servers that don't handle this
correctly.

  3. We should practice what we preach in the spec.  For instance in RFC
2518 example 8.10.8, we have <D:href> inside an <owner> tag that could cause
certain servers to have the problem described here.

  4. We should keep general scenario in mind when writing specs in the
future that involve one party saving XML with namespace tags in it from
another party, possibly saying that the client MUST send self-contained XML.

  Alas, since RFC 2518 is a done-deal there's not much we can do on #3.
Issues #1 and #2 are mostly education issues for WebDAV client and server
implementers.  The main reason I'm writing this is for #4, so that we can be
aware of this scenario in the future.

  Thank you,
  John Spaith
  Software Design Engineer
  Windows CE
  Microsoft
Received on Friday, 20 September 2002 13:12:54 GMT

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