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RE: WSD WG requests to XML Schema WG

From: Jonathan Marsh <jmarsh@microsoft.com>
Date: Wed, 25 Feb 2004 13:54:32 -0800
Message-ID: <DF1BAFBC28DF694A823C9A8400E71EA202B9531D@RED-MSG-30.redmond.corp.microsoft.com>
To: <w3c-xml-schema-ig@w3.org>
Cc: <www-ws-desc@w3.org>

I've created a draft agenda for the WSDesc WG [1].  Here's the part that
might be relevant for Schema folks to sit in on (though I'm not billing
this as a joint session, as it also includes WSDL-specific stuff):

[Thursday]
13:30 Issue 109: WSDL versioning [10]
    - Use cases (DavidO) [11]
    - Requirements (PaulD) [12]
    - Scenarios
      [***** ACTION: DaveO to write up a proposal for augmenting 
                     schema information to enable versioned data. *****]
    - Note: Schema folks might be want to join for this topic.

 [10] http://www.w3.org/2002/ws/desc/2/06/issues.html#x109
 [11] http://lists.w3.org/Archives/Public/www-ws-desc/2004Jan/0016.html
 [12] http://lists.w3.org/Archives/Public/www-ws-desc/2004Feb/0082.html

14:30 Issue 140: Version attribute [13]
    - Tom's initial proposal [14] and follow-on proposal [15]
      [*****Need clear enumeration of options*****]

 [13] http://www.w3.org/2002/ws/desc/2/06/issues.html#x136
 [14] http://lists.w3.org/Archives/Public/www-ws-desc/2004Feb/0049.html
 [15] http://lists.w3.org/Archives/Public/www-ws-desc/2004Feb/0069.html

15:30 Break

[1] http://lists.w3.org/Archives/Public/www-ws-desc/2004Feb/0218.html


> -----Original Message-----
> From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]
On
> Behalf Of David Orchard
> Sent: Wednesday, February 18, 2004 10:41 AM
> To: w3c-xml-schema-ig@w3.org
> Cc: www-ws-desc@w3.org
> Subject: WSD WG requests to XML Schema WG
> 
> 
> Dear Schema WG,
> 
> On behalf of the WSDL WG I'm conveying a use case for versioning, a
> question about a solution and the intentions for Schema 1.1, and a
> suggestion
> to meet at the plenary F2F.
> 
> The WSDL WG is attempting to emerge from our Mar 4-5 FTF with a
> Last-call ready Core specification.  We have an oustanding action item
to
> investigate WSDL solutions to describing extensible and versionable
> Web services.  There are several avenues toward a solution which
include
> exploring fixes directly to Schema to allow evolution of message
> structure, ways we might layer on top of Schema to provide these
> capabilities,
> and encouraging use of alternative Schema languages.  A solution
available
> in XML Schema 1.1 may be attractive to us and our customers.
> 
> Although we are meeting at the FTF, we are not meeting concurrently
with
> your group; but perhaps there is an opportunity for a few Schema WG
> members to join us on Thursday to explain our needs and explore
> solutions.
> 
> In discussions on Providing Compatible Schema Evolution [1], the broad
> question of extensibility and versioning as a whole was examined. And
> there
> are tricky problems and difficult choices for solutions. Another
important
> question to ask is what is the minimum necessary for success in
> versioning?
> If one assumes that we do not need to insert elements in arbitrary
places,
> just at the end, and retaining compatibility, then there may be a
simpler
> solution that XML Schema 1.1 could do. Let us take a simple name
example
> through two iterations. The first iteration adds an optional "middle"
name
> at the end of the name. The second option adds an optional "suffix" at
the
> end of the extended name.  This looks like:
> 
> <name>
> 	<first>Dave</first>
> 	<last>Orchard</last>
> </name>
> 
> <name>
> 	<first>Dave</first>
> 	<last>Orchard</last>
> 	<middle>Bryce</middle>
> </name>
> 
> <name>
> 	<first>Dave</first>
> 	<last>Orchard</last>
> 	<middle>Bryce</middle>
> 	<suffix>II</suffix>
> </name>
> We want these 3 of these documents to be valid against the 3 schemas.
It
> seems that the simplest change would be to have a "low priority"
wildcard
> as
> mentioned in previous discussions. The schemas using this would be
> something
> like:
> 
> <xs:complexType name="nameType">
> 	<xs:sequence>
> 		<xs:element name="first" type="xs:string" />
> 		<xs:element name="last" type="xs:string" minOccurs="0"/>
> 		<xs:any namespace="##any"/>
> 	</xs:sequence>
> </xs:complexType>
> 
> <xs:complexType name="nameType">
> 	<xs:sequence>
> 		<xs:element name="first" type="xs:string" />
> 		<xs:element name="last" type="xs:string" minOccurs="0"/>
> 		<xs:element name="middle" type="xs:string"
minOccurs="0"/>
> 		<xs:any namespace="##any"/>
> 	</xs:sequence>
> </xs:complexType>
> 
> <xs:complexType name="nameType">
> 	<xs:sequence>
> 		<xs:element name="first" type="xs:string" />
> 		<xs:element name="last" type="xs:string" minOccurs="0"/>
> 		<xs:element name="middle" type="xs:string"
minOccurs="0"/>
> 		<xs:element name="suffix" type="xs:string"
minOccurs="0"/>
> 		<xs:any namespace="##any"/>
> 	</xs:sequence>
> </xs:complexType>
> 
> It seems that a low priority wildcard is sufficient to enable an
explicit
> extensibility point that allows backwards and forwards compatible
> evolution
> through multiple versions with extension at the end of the type
definition
> and extension in the same namespace. This isn't the fullest solution,
as
> it
> does not allow for default extensibility, nor extensibility in between
> elements. But this appears significantly improved over current
> capabilities.
> 
> I'm not able to track the intricacies of the discussion, but it
appears
> that
> the Schema group is talking about this in the context of RQ-135, with
a
> proposal at [2], another proposal about 2nd class wildcards at [3],
and a
> fair amount of follow on discussion.  Again, I can't follow through
the
> intricacies of the discussion of the ilk of subsumption of lexical
spaces
> versus value spaces for redefinition, and why a validator needs to
look up
> the tree for subsumption.
> 
> We are interested in determining whether the Schema WG sees: this use
case
> as important for Schema 1.1, whether this use case will be solved in
> Schema
> 1.1, if low priority wildcards are a solution to this problem, if
> low-priority wildcards will be the Schema 1.1 solution
> 
> On behalf of the WSDL WG,
> Dave Orchard
> 
> [1]
>
http://www.pacificspirit.com/Authoring/Compatibility/ProvidingCompatible
Sc
> he
> maEvolution.html
> [2] http://lists.w3.org/Archives/Member/w3c-xml-schema-
> ig/2004Feb/0028.html
> [3] http://lists.w3.org/Archives/Member/w3c-xml-schema-
> ig/2004Feb/0035.html
Received on Wednesday, 25 February 2004 16:54:31 UTC

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