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Posted to j-dev@xerces.apache.org by "Michael Glavassevich (JIRA)" <xe...@xml.apache.org> on 2011/02/10 21:12:57 UTC
[jira] Issue Comment Edited: (XERCESJ-1496) adding new feature to
JAXP validator for folded simpleType->list assertions evaluation
[ https://issues.apache.org/jira/browse/XERCESJ-1496?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12993200#comment-12993200 ]
Michael Glavassevich edited comment on XERCESJ-1496 at 2/10/11 8:11 PM:
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Mukul, it seems like the new behaviour introduced by this feature (when set to true) is a bug fix and that the current behaviour (when the feature is set to false) is a defect. It's unusual to fix a bug by introducing a new JAXP feature, especially when the default is to continue supporting the buggy behaviour. Remember that the XML Schema 1.1 spec and the implementation in Xerces are still in development. I doubt that any of our users would have a dependency on the current behaviour or an expectation that things are stable since we've clearly told them that this is experimental stuff at the moment. Can we fix the issue discovered by this W3C test cleanly and not introduce a new feature?
was (Author: mrglavas@ca.ibm.com):
Mukul, it seems like new behaviour introduced by this feature (when set to true) is a bug fix and that the current behaviour (when the feature is set to false) is a defect. It's unusual to fix a bug by introducing a new JAXP feature, especially when the default is to continue supporting the buggy behaviour. Remember that the XML Schema 1.1 spec and the implementation in Xerces are still in development. I doubt that any of our users would have a dependency on the current behaviour or an expectation that things are stable since we've clearly told them that this is experimental stuff at the moment. Can we fix the issue discovered by this W3C test cleanly and not introduce a new feature?
> adding new feature to JAXP validator for folded simpleType->list assertions evaluation
> --------------------------------------------------------------------------------------
>
> Key: XERCESJ-1496
> URL: https://issues.apache.org/jira/browse/XERCESJ-1496
> Project: Xerces2-J
> Issue Type: Improvement
> Components: XML Schema 1.1 Structures
> Affects Versions: 2.11.0
> Reporter: Mukul Gandhi
> Assignee: Mukul Gandhi
> Priority: Minor
>
> Here's a description of the rationale and benefits of this change, and a small schema 1.1 validation use case illustrating the proposed changes.
> One of the test cases in W3C XML Schema 1.1 test suite is as follows:
> XML document [1]:
> <list>1 2 3 4 5</list>
> XML Schema 1.1 document [2]:
> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
>
> <xs:element name="list">
> <xs:simpleType>
> <xs:list>
> <xs:simpleType>
> <xs:restriction base="xs:integer">
> <xs:assertion test="count($value) eq count(distinct-values($value))" />
> </xs:restriction>
> </xs:simpleType>
> </xs:list>
> </xs:simpleType>
> </xs:element>
>
> </xs:schema>
> The assertion facet in this example would mean,
> "there must be no duplicates in the list"
> Xerces (before this change) didn't support an use case like above. For the above example currently Xerces evaluates assertion for each list item (therefore Xerces would make 5 calls to an assertion for this example, and the XPath 2 context variable $value being different/"list item" in each iteration) -- but this would not serve the purpose of this use case.
> I believe we must support this use case. To support this facility I propose a change along the following lines:
> We introduce a new feature on JAXP validator with name "http://apache.org/xml/features/validation/foldedSTlist-assertion-evaluation" whose default value is an boolean 'false' (therefore not setting this feature or making it explicitly 'false' would retain the current Xerces behavior). Setting this feature to 'true' would cause assertion evaluation as required by the above use case.
> The current Xerces implementation to evaluate assertion facet on each list item is also beneficial; for example with a schema 1.1 fragment something like below:
> <xs:element name="list">
> <xs:simpleType>
> <xs:list>
> <xs:simpleType>
> <xs:restriction base="xs:integer">
> <xs:assertion test="$value mod 2 = 0" />
> </xs:restriction>
> </xs:simpleType>
> </xs:list>
> </xs:simpleType>
> </xs:element>
> (the assertion failure error messages in this example would tell us, that what all list items didn't pass the test AND I believe that this run-time behavior is also useful)
> To summarize this change:
> 1. Setting the mentioned JAXP feature to 'true' would cause assertion to be evaluated only once on the entire list (which would have a type annotation xs:anyAtomicType*).
> 2. Not setting this JAXP feature explicitly (since it's default value is 'false' within Xerces XML Schema 1.1 validator), or setting explicitly it's value to 'false' would retain the current Xerces behavior as has been explained above.
> I hope that this enhancement is useful. I'll shortly be committing changes for this facility (along with related support to jaxp.SourceValidator sample). Any comments about this change would be helpful to us.
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