users@jaxb.java.net

Re: Schema evolution in JAXB 2.0

From: Joe Fialli <Joseph.Fialli_at_Sun.COM>
Date: Wed, 03 Nov 2004 12:02:43 -0500

George Datuashvili wrote:

>This is a *very* desirable goal, but it's going to be tough to address
>schema evolution issue in JAXB2 specification when XSD specification
>itself makes it nearly impossible. As Noah Mendelsohn wrote recently,
>W3C XSD WG is well aware of problem and is considering options to fix
>it. He also wrote one proposal:
>
>http://lists.w3.org/Archives/Public/www-tag/2004Aug/att-0009/NRMVersioni
>ngProposal.txt
>
>
It is true that JAXB 2.0 specification can not fix all issues in XSD
specification concerning schema evolution.
For example, the XSD specification does not provide one standard way to
specify schema version and how an
xml document represents what version of the schema constrains the xml
document. Also, XSD validation
needs to be more flexible to allow for schema evolution.

However, we are discussing in JAXB 2.0 EG on defining a flexible
unmarshalling mode
that binds invalid content in a predictable way for a class of invalid
content xml documents. JAXB 1.0 specification did not attempt to
specify any unmarshalling techniques
for processing invalid content. While this is not a solution to handle
schema evolution, it does attempt to
make a small step towards assisting what happens when a schema evolves
and one attempts to unmarshal an xml document
that is not constrained precisely by the JAXB compiled schema.

We are targetting the flexible unmarshalling mode for a followup early
draft version of the JAXB 2.0 specification
and would appreciate feedback on whether these steps we are proposing
will assist those with
schema evolution issues. We will announce the availability of JAXB 2.0
Early Draft 2 specification to this alias when it
is made available. (Sorry I don't have a date for the release of Early
Draft 2 at this time.)

-Joe


>Thanks,
>George
>
>
>
>>-----Original Message-----
>>From: Ian Poccachard [mailto:ipocca_at_blueyonder.co.uk]
>>Sent: Monday, November 01, 2004 9:07 AM
>>To: users_at_jaxb.dev.java.net
>>Subject: Schema evolution in JAXB 2.0
>>
>>Hi guys,
>>
>>I am interested to know more about the views of the expert
>>group regarding schema evolution.
>>
>>I checked out the JAXB 2.0 Early Draft v0.4 June 10, 2004.
>>Section 1.2 lays out the goals, item 7 refers explicitly to
>>schema evolution.
>>
>>Can someone give an informed view of what is likely to be
>>available say by the end of 2005? The early draft was a little vague.
>>
>>Regards
>>
>>Ian
>>
>>
>
>
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