>Xerces getting XPath 2.0 support?

>It looks like with the work that is going on for the support of XML Schema 1.1, that Xerces might also be getting XPath 2.0 support. Personally, I think it is a good thing, since the XPath 2.0 parser and XSLT 2.0 version of Xalan seems to be stuck in limbo. I had high hopes of trying to revive the Xalan XSLT 2.0 processor, but just do not have enough cycles, and it is currently low on my priority list. However, I’m glad to see a possible Apache Licensed XPath 2.0 implementation in the works.

One of the items we have outstanding in XSL Tools is to provide XPath 2.0 validation. So having an Apache Licensed implementation will go a long way to helping to implement this.

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7 Responses to >Xerces getting XPath 2.0 support?

  1. >That’s great news, especially for the Eclipse ecosystem as the XPath 2.0 support evolves under the APL.

  2. mrglavas says:

    >Before folks get too excited, the XPath 2.0 support under discussion is the required subset for Type Alternatives, which is far less than all of XPath 2.0.

  3. David Carver says:

    >@mrglavas: Any thought from the XERCES team of reviving or reusing portions of the Xalan XSLT 2.0 project code that is in Apache source code control for the XPath 2.0 engine…would allow for the full power of the assertions in XML Schemas 1.1 to be implemented, and would give a starting base to begin instead of recreating from scratch.

  4. >I understand the work done in Xalan never went very far and is possibly not even in line with the W3C Recommendation (as the work which was done pre-dates it by years). I have no sense of whether what’s there is still relevant and could be continued.In Xerces there’s been no discussion about implementing full XPath 2.0. It would be a huge undertaking for a small team of developers who are not even experts in that area.I’ve seen the requests on the Xalan lists for XPath 2.0 and XSLT 2.0 support, but have yet to see anyone offer to do anything to make that happen. Unless we get some new volunteers with the time, interest and knowledge I’d say it’s pretty unlikely for native support to be implemented in Xerces or Xalan. The critical mass just isn’t there today.For assertions, I’ve been assuming we’d rely on another library or provide some way for users to plug-in the XPath processor of their choice.

  5. David Carver says:

    >Actually, from the limited testing that I’ve done with the code that is in the repository for Xalan with XSLT 2.0 and Xpath 2.0 support it doesn’t appear to be that far off. As for using another XPath processor for the assertions, the problem is that the only open source processor that supports XPath 2.0 is SAXON, and Saxon has IP concerns both at eclipse and apachee. So unless there is an Apache friendly licensed java xpath 2.0 processor that I don’t know about, relying on plugging in is going to limit the vast majority of commercial adopters to 1.0, unless they feel comfortable assuming the possible IP issues with Saxon.I work on the XSL Tools support for eclipse, and general XML development when I get a chance. And the user community keeps asking about XPath 2.0 support as well as XSLT 2.0 support.I know of several people that have sent responses or expressed interest in helping the XALAN team with XPath 2.0 and XSLT 2.0 implementation, taking the existing code that was started and continuing it, but no responses on their dev mailing list.One of the big concerns is going to be compatibility amongst XML Schema 1.1 implementations if the tooling is supporting various flavors of XPath for assertions. You’ll have a interoperability nightmare if Saxon users implement 2.0, and Xerces only supports a limited subset of xpath.I understand the resource constraints though.

  6. >Users who want an open source implementation need to understand that it is within their power to make it happen. And if they are so motivated they can group together and form a development community in Apache or elsewhere, possibly revitalizing the work in Apache if that is their goal or starting their own project somewhere. They can be part of the team if they want to be.My reading of the general apathy to contribute is that the people asking thus far haven’t needed it badly enough yet. Sure some of them may have written an e-mail on one of the mailing lists offering to possibly do something. If it really mattered to them they’d follow-up or find other avenues to get the ball rolling (e.g. starting a thread on the xml-dev mailing list). When it starts to hurt enough maybe folks will actually do something about it.

  7. David Carver says:

    >I totally agree that when it hurts enough somebody will do it. However, for most people that want XPath 2.0 or XSLT 2.0, they just go use saxon. The pain point comes when one can’t distribute bundle Saxon because of IP concerns. They are looking into these supposed concerns at eclipse. With that said, I need to check with eclipse IP on what type of issues I would have with bring the sorta working XPath 2.0 implementation in Xalan that was never released over as an Eclipse project.I just haven’t had enough free cycles yet to get that ball rolling.

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