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From http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2008Mar/0002.html Why is "schema-less identification of reference elements" important, when schema validity assessment is a fundamental part of model validation? Or, even more strongly, if this spec. is _really_ about allowing people to express link integrity conditions on collections of documents, why can't I use it to do the most obvious and simple of integrity checks, that is, check that all the links in my XHTML document resolve? It would be easy, and arguably cleaner, to annotate schemas with sml:ref instead of instances!
The WG discussed this issue during it's 2008-03-13 telecon. Some reasons were given for why "schema-less recognition" is useful. In particular, "Schemaless identification of references was driven by scenarios that required references to be quickly identified; when models were being exchanged, stored, or retrieved and these operations required references to be transformed." For example, if a model is known to be valid, then in certain cases processing the model quickly without going through schema validation would be desirable. The WG did discuss the possibility to honor schema-defaulted sml:ref=true, and did agree to support it. It seems that decision didn't find its way into the draft.
Proposal to implement WG's earlier decision to support schema-defaulted sml:ref. In section 4.1.1, where reference recognition is discussed, replace the paragraph starting with "This mechanism enables schema-less ..." with the following: "It is implementation-defined whether to use the XML Infoset [ref] or the Post Schema Validation Infoset (PSVI) [ref] for SML reference identification. Using the XML Infoset enables SML reference identification without relying on XML Schema validation. Using the PSVI makes it possible to identify SML references using schema defaulted sml:ref attributes."
As per the resolution on 3/27 call, fix as per Comment #2
Adding to Comment #3 ------- The SML WG believes that the above proposal resolves this issue fully. I'm changing its status accordingly. The change in status should cause email to be sent to the originator of this issue, to whom the following request is addressed. Please review the changes adopted and let us know if you agree with this resolution of your issue, by adding a comment to the issue record and changing the Status of the issue to Closed. Or, if you do not agree with this resolution, please add a comment explaining why. If you wish to appeal the WG's decision to the Director, then also change the Status of the record to Reopened. If you wish to record your dissent, but do not wish to appeal the decision to the Director, then change the Status of the record to Closed. If we do not hear from you in the next two weeks, we will assume you agree with the WG decision.
Fixed per comment #2. See diff at: http://www.w3.org/2007/10/htmldiff?doc1=http%3A%2F%2Fdev.w3.org%2Fcvsweb%2F%7Echeckout%7E%2F2007%2Fxml%2Fsml%2Fbuild%2Fsml.html%3Frev%3D1.191%26content-type%3Dtext%2Fhtml%3B%2520charset%3Diso-8859-1&doc2=http%3A%2F%2Fdev.w3.org%2Fcvsweb%2F%7Echeckout%7E%2F2007%2Fxml%2Fsml%2Fbuild%2Fsml.html%3Frev%3D1.192%26content-type%3Dtext%2Fhtml%3B%2520charset%3Diso-8859-1 Note that a new entry was added to the Normative References: ------------------ [XML Information Set] XML Information Set (Second Edition),John Cowan, Richard Tobin, Editors. World Wide Web Consortium, 4 February 2004. This version of the XML Information Set Recommendation is http://www.w3.org/TR/2004/REC-xml-infoset-20040204/. The latest version of XML Information Set is available at http://www.w3.org/TR/xml-infoset/. ---------------
1. I think we need to add a <li> to SMLIF 4.5 Interoperability of SML Models as a result of this change. Consumers that make a different impl-defined choice about whether or not to use PSVI are not always going to provide consistent validation results (eg in the presence of schema-defaulted sml:ref). 2. This change also makes 4.5 Interoperability of SML Models item 1 no longer strictly true, since two implementations might not recognize the same set of references. 3. "Interoperability of SML Models" (sic) seems like an odd title for a chapter in the SMLIF spec. Editors' discretion given (by me, cannot speak for the full wg); something like "Interoperability of SML Model Exchange" seems more in keeping with SMLIF's role, and the <p> text immediately following the heading.
resolution (conf call on 4/17/2008): remove the 'decided' keyword because the 2 week response period has elapsed (see comment# 4).
For the record, at its call of 4 April the XML Schema WG endorsed this comment. A clear account of the relation between model validity and schema validity is highly desirable. When the final textual changes are ready (but not before), I will take the SML WG's response to the issue back to the Schema WG so they can decide whether they believe the issue has in fact been resolved successfully.
resolution in conf call (5/1/08): mark needsAgreement (need agreement in view of comment# 6)
Comment #8 includes a sentence about the relation between SML model validity and schema validity; that is an error. The Schema WG did endorse the issue tracked in this bug report, but the reference to model validity relates to bug 5519 not to this one. Sorry for the cut/paste error.
Regarding comment #6, bullet 3 - I propose a simplified title of "Interoperability".
Regarding comment #6, bullet 1 and 2, see my comments at http://lists.w3.org/Archives/Public/public-sml/2008May/0087.html
As per discussion in 5/29 call, Kumar and Ginny will work on a proposal and get back to the WG
Ginny & I have the following proposed changes: [1] Update section 4.1.1 SML Reference, 1. Convert existing sentence this mechanism to non-normative. 2. Add new non-normative note about validators . The resultant note would look like below: Note: 1. This mechanism enables schema-less identification of SML reference, i.e., SML references can be identified without relying on the Post Schema Validation Infoset. [XML Schema Structures]. 2. SML model validators must use PSVI to identify SML references as defined in section 8 Conformance. [2] Add item# 6 to section 8. Conformance Criteria: 6. The validator MUST identify all SML reference in the model using PSVI.
Resolution in 6/12 call - fix as per comment #14 The SML WG believes that the above proposal resolves this issue fully. I'm changing its status accordingly. The change in status should cause email to be sent to the originator of this issue, to whom the following request is addressed. Please review the changes adopted and let us know if you agree with this resolution of your issue, by adding a comment to the issue record and changing the Status of the issue to Closed. Or, if you do not agree with this resolution, please add a comment explaining why. If you wish to appeal the WG's decision to the Director, then also change the Status of the record to Reopened. If you wish to record your dissent, but do not wish to appeal the decision to the Director, then change the Status of the record to Closed. If we do not hear from you in the next two weeks, we will assume you agree with the WG decision.
Fixed per comment #14. See section 4.1.1 and 8 in diff: http://www.w3.org/2007/10/htmldiff?doc1=http%3A%2F%2Fdev.w3.org%2Fcvsweb%2F%7Echeckout%7E%2F2007%2Fxml%2Fsml%2Fbuild%2Fsml.html%3Frev%3D1.219%26content-type%3Dtext%2Fhtml%3B%2520charset%3Diso-8859-1&doc2=http%3A%2F%2Fdev.w3.org%2Fcvsweb%2F%7Echeckout%7E%2F2007%2Fxml%2Fsml%2Fbuild%2Fsml.html%3Frev%3D1.220%26content-type%3Dtext%2Fhtml%3B%2520charset%3Diso-8859-1
+1
I am happy with this resolution