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Bug 2824 - RQ-151 Define schema composition (composition)
Summary: RQ-151 Define schema composition (composition)
Alias: None
Product: XML Schema
Classification: Unclassified
Component: Structures: XSD Part 1 (show other bugs)
Version: 1.1 only
Hardware: Other All
: P2 normal
Target Milestone: ---
Assignee: C. M. Sperberg-McQueen
QA Contact: XML Schema comments list
Whiteboard: important, hard; composition cluster
Keywords: needsAgreement
: 5374 (view as bug list)
Depends on:
Reported: 2006-02-11 00:36 UTC by C. M. Sperberg-McQueen
Modified: 2008-01-15 22:23 UTC (History)
1 user (show)

See Also:


Description C. M. Sperberg-McQueen 2006-02-11 00:36:47 UTC
This issue was originally reported by Xan Gregg.

    Give a complete and formal definition of schema composition,
    and use it for currently defined (e.g. include) and
    currently undefined (e.g. schema docs on command line) cases.


This item was classified as Req in the meeting of 2004-06-10

This topic has been discussed at some length and working papers have
been prepared for the WG both by Noah Mendelsohn and by Michael

Following our discussion at the 2005 Technical Plenary, MSM was asked
to prepare a new proposal. His plan is first to outline a notation for
describing the XML mappings (following on from NM's proposal presented
in January 2005).  That notation should make it easier to have clearer
discussions of identity conditions on components; once the identity
conditions on components are clearer, the core of this requirement can
be addressed more readily.
Comment 1 C. M. Sperberg-McQueen 2006-07-27 17:43:57 UTC
The working papers mentioned in the description are 
currently member-only (alas), but for those with
member access the following URIs should be of interest:

XML Schema Composition:  An attempt to clearly set out 
our current design (Noah Mendelsohn, June 2004).

Notes on RQ-151 (C. M. Sperberg-McQueen, July and
November 2004):

Branch draft of Structures (diffed) showing possible changes
(Noah Mendelsohn, January 2005).
(See also
for pointers to other forms of the branch draft and auxiliary
Comment 2 C. M. Sperberg-McQueen 2007-08-03 18:36:42 UTC
On its telcon today, the Working Group discussed this and other issues
related to schema composition and concluded (not without some pangs of
regret) that for scheduling reasons it is not feasible for us to
resolve them before we go to Last Call.

The WG continues to believe that this issue is important and should be
resolved; our decision to close the issue for now reflects the fact
that we have not been able to reach consensus on how to resolve the
problems related to composition, coupled with the observation that for
the most part, users are able to avoid the problems by avoiding
problematic constructs in their schema documents.  The cost of
delaying XSDL 1.1 for these issues is thus high, while the practical
benefit for users is not as high as it might be.

The Working Group continues to hope that this issue can be resolved at
some point in the future.  Accordingly I am closing this issue with a
disposition of LATER.  
Comment 3 Mary Holstege 2008-01-15 22:23:27 UTC
*** Bug 5374 has been marked as a duplicate of this bug. ***