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Minutes: XML Schema Patterns for Databinding Telcon 18 March 2008

From: <paul.downey@bt.com>
Date: Wed, 19 Mar 2008 11:35:14 -0000
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To: <public-xsd-databinding@w3.org>

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                                                             - DRAFT -

                                  XML Schema Patterns for Databinding Working Group Teleconference

18 Mar 2008

   See also: IRC log


          Jon Calladine (BT)
          George Cowe (Origo Services Limited)
          Paul Downey (BT)
          Yves Lafon (W3C)




     * Topics
         1. Patterns Detection
         2. ISSUE-2: test suite
         3. Charter Renewal?
         4. Status of Basic Patterns
         5. Last Call comments from Schema WG
         6. lc-xsd-5
         7. lc-xsd-6
         8. lc-xsd-7
         9. lc-xsd-8
        10. lc-xsd-9
        11. lc-xsd-10
        12. lc-xsd-11 Editorial Concerns
        13. Status of Publication
     * Summary of Action Items

   minutes from 2008-3-11 teleconference 2008-2-19 teleconference approved

  Patterns Detection

   pauld: built annotation
   ... see the examples and collection pages

   gcowe: will look at optionally adding it to the service


  ISSUE-2: test suite

   gcowe: the XBinder guys picked up an old copy of the testsuite and sent results

   pauld: cool!

   gcowe: we've added a load more tests, so I sent them a new copy

   pauld: that's great. Many thanks!
   ... collection is now checked in with annotation!
   ... what's next for the test suite?

   gcowe: not a lot, we've run the tools we can, half the toolkits missing, Adrian had the ability to run them

   pauld: but for basic, how do we stand?

   <gcowe> http://www.w3.org/2002/ws/databinding/edcopy/report/basic.html

   pauld: I can rerun SOAP4R and ZSI, can someone help with WCF

   <Yves> I am doing gsoap c and c++

  Charter Renewal?

   pauld: dependent on publishing Last Call documents

   yves: we should be able to ask for another six months

  Status of Basic Patterns

   pauld: thanks George for the work on differencing
   ... status section needs updating further

  Last Call comments from Schema WG



   * Schema documents vs. schemas: Following up on the point above, there are
   schema documents that do not stand on their own in defining a schema
   that's useful for validation. For example, if a schema document merely
   defines a complext Type T as being derived by extension from type B with
   attribute A, then you don't really know what the type is until you find
   the base type B, and that may well be in a different schema document.
   Maybe there is element content in effective type T. If there is an
   element E declared of type T, then what does the requirement to "[expose]
   all of the [XML 1.0] element node and attribute node content described by
   the originating [XML Schema 1.0] document" mean? The problem is that it's
   not really schema documents that directly call for or don't call for
   content in documents to be validated. Schema documents contribute to the
   construction of a schema (formally defined at [4]), which in turn contains
   element declarations, etc. that can be used to require or allow content
   in documents to be validated. >>It seems that some serious thought is
   needed as to whether it's schema documents or schemas that would conform
   to the databinding specification.<< In any case, referring to the
   element or attribute content "described by a schema document" is not just
   too informal; as suggested above, it's likely that you really want to
   talk about the element or attribute content allowed by a schema.
   Conversely, you could more clearly define a set of rules relating to
   individual schema documents if that's what you really intend.

   pauld: this is related to the infoset (v) document issue. It would be much harder to write test tools for this

   yves: we're testing for bytes on the wire, not at the infoset level

   pauld: the only way I could see this working is if they had an XML format for their infoset or even the PSVI
   ... anyone want to support this comment?


   RESOLUTION: lc-xsd-5 rejected


   * Section 1.4 says that conformance requires that an implementation: "MUST
   be able to consume any well-formed [XML 1.0] document which satisfies
   local-schema validity against the originating [XML Schema 1.0] document
   exposing all of the [XML 1.0] element node and attribute node content in
   the data model." Again, local-schema validity is not a relation defined
   on the pair {instance, schema document}, it is (presuming you indicate
   which type or element declaration to start with) defined on the pair
   {instance, schema}"

   pauld: anyone feel like they have better words for this assertion?


   gcowe: let's ask them for better text!

   <scribe> ACTION: pdowney to ask the Schema WG for advice [recorded in

   <trackbot-ng> Created ACTION-129 - Ask the Schema WG for advice [on Paul Downey - due 2008-03-25].

   pauld: so we accept the comment, but don't have the skills to address it to schema WG's satisfaction


   * Section 2: "The [XPath 2.0] expression is located from an [XML Schema
   1.0] element node which may be the document element, or an element
   contained inside an [XML 1.0] document such as [WSDL 2.0] description."

   It's not quite clear what is meant in saying that an "[XPath 2.0]
   expression is located from". Is this trying to establish the "Context
   Node" for the XPath expression as being the node of the <xsd:schema>
   element? If so, we recommend you say that more clearly, preferably with
   hyperlinks to the pertinent parts of the XPath Recommendation. Also, the
   phrase "may not" can be read as prohibiting the case where the element
   note is the document node. I suspect you meant "need not". Finally, [XML
   Schema 1.0] element node isn't a term that appears in the XSD
   Recommendation; did you mean the "root element information item of the
   schema document"?

   pauld: accept "need not" change to text
   ... suggest a note to say "this is to establish the Context node for the XPath expression"
   ... seems reasonable to link to the XPath recommedation

   RESOLUTION: accepted lc-xsd-7 with suggested text changes


   * Sections 2.x: The phrase "An [XML 1.0] document exibits the XXXXX
   pattern...." is used repeatedly in these sections and their descendents.
   See comments about about need to refer to "schema documents", if that's
   what's intended.

   pauld: looks like the documents (v) infoset comment again

   yves: is that the instance document?

   pauld: we could be clearer that it's a WSDL 1.0, 2.0, Schema, whatever, but balooning the boilerplate isn't desirable
   ... we already have "2.1 Schema Element

   The xs:schema element MAY be the document element, but MAY also appear within other descriptions such as a [WSDL 2.0] or
   [WSDL 1.1] document. /-"

   yves: text tied up better to the "An [XML 1.0] document exhibits the"

   RESOLUTION: accepted lc-xsd-5 as requiring clarification



   * Section 2.1.2: talks about qualified local elements, but the sample
   schema contains no local elements.

   pauld: we could change the example to include local elements

   gcowe: what does that mean for the test suite? is this one excluded?

   pauld: I suspect this is something we've excluded, so it could be safe

   could risk introducing an advanced pattern

   example something like:

   <xs:element name="foo">
         <xs:element ..
         <xs:element ..

   gcowe: will update example

   RESOLUTION: accepted lc-xsd-9, will expand example


   * Section 2.1.6: BlockDefault. This pattern seems to imply that
   substitutions and or derivations are blocked if the @blockDefault
   attribute is provided, but in fact that attribute carries a value that can
   selectively enable or disable blocking for any combination of extension,
   restriction, and substitution. It seems unlikely that the rule of
   interest is really that the attribute is present. Is that what's
   intended, or did you wish to actually check for certain values of the
   blockDefault. Note, in particular, that an explicit blockDefault="" has
   the same semantic as leaving out the attribute entirely.
   I regret that I did not have time to review the remainder of the patterns
   in the draft, but I would assume that the above comments would be
   representative of what would be found for other patterns.

   jonc: mea culpa!
   ... pattern needs tightening up,

   pauld: it's been moved to Advanced anyway

   <scribe> ACTION: jcalladi to sort out BlockDefault patterns [recorded in

   <trackbot-ng> Created ACTION-130 - Sort out BlockDefault patterns [on Jonathan Calladine - due 2008-03-25].

   RESOLUTION: accepted lc-xsd-10, BlockDefault has been moved to Advanced

  lc-xsd-11 Editorial Concerns

   The databinding draft is very long, and a lot of it is devoted to what is
   ultimately boilerplate. Consider the targetNamespace pattern. It is
   introduced with nearly 1/2 page of multicolor writeup, but really all it's
   trying to say seems to be: This pattern requires that the schema
   document have a targetNamespace attribute with an absolute URI as its
   value. That could be said much more clearly and concisely. I think the
   draft would be much more effective if the patterns were introduced in a
   manner that was as concise and clear as possible. It's not helpful to
   repeat over and over "An [XML 1.0] document exhibits....", and as noted
   above, the example schema could be made shorter and clearer. Finally,
   what would be most helpful for a pattern like this is to explain ">>why<<
   an absolute URI"? The Schema recommendation points to the XML Namespaces
   recommendation for the definition of a namespace name, and that in turn
   requires a URI Reference [5], not an Absolute URI. So, it would be
   useful in general if some of the boilerplate were eliminated and the
   sections made much shorter and easier to read, but conversely it would be
   useful to say a bit about what makes the pattern interesting. Explain
   briefly if there's a reason why absolute namespace URIs are interesting,
   or did you really just mean this pattern to be "a non-absent
   targetNamespace is available"?

   pauld: OK, so whatabout our extensive use of boilerplate?

   pauld: it's not a very human readable spec!

   gcowe: it is computer generated

   jonc: hard to avoid


   pauld: we could have written another Schema primer, but our work has been driven by the test suite and our patterns
   detector resulting in a concrete testable document. Without a strong proposal of contributed annotated text, I'm going to
   push back.

   jonc: discussion was it's opening the flood gates, and this is for the primer

   pauld: I know, I'm not keen on specs which justify themselves
   ... we're pretty clear why a pattern is Basic or Advanced
   ... we're not clear on how patterns come about
   ... sounds like something we could add as editorial text, volunteers?
   ... we've done a lot of work in terms of test tools and suites, and that' the best approach IMO

   jonc: in the past I have argued for Noah's position, but it's seems best left to additional documents and discussion, on a

   pauld: XML was famously wafted by Tim Bray as a small spec, then the first thing he did was publish an "annotated version".
   You're free to do the same :)
   ... I think its' fair comment to say why a pattern is interesting. Hmm. Will look at that generically in the introduction.

   RESOLUTION: accepted lc-xsd-11 in part, will add more introduction text

  Status of Publication

   pauld: all of the comments accepted are editorial, any objections to incorporating the text and then going ahead to Last
   Call as planned?

   *None heard*

   pickup again next tuesday

Summary of Action Items

   [NEW] ACTION: jcalladi to sort out BlockDefault patterns [recorded in
   [NEW] ACTION: pdowney to ask the Schema WG for advice [recorded in
Received on Wednesday, 19 March 2008 11:35:59 UTC

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