As of this writing there’s no roadmap that contains support for W3C XML Schema.

However, very many people ask for it so I will surely bring it up for strong consideration for Qt 4.5.

Until then; schema validation gives deterministic data handling(since the input data has been validated), and XQuery does bring some of the same advantages, although not in the absolute sense that Schema do.

XQuery has all the builtin primitives that W3C XML Schema has, and treat those in a type aware manner. If one writes ones XML code in XQuery, one achieves a fairly high degree of data integrity and code stability, which is the same advantages that Schema gives.

I suppose the huge memory requirement issue has been controlled ? I
don’t know how libxml handles it, but I’ve found no performance issues
with xmlstarlet or xsltproc so far, albeit with fairly small XML
files…

I vaguely recall what this was about, but tons of things have changed since the code was in KDE. Among other things a new representation is used, which is about half the size of QDom. Though, I’m for good reasons not satisfied with it yet, so keep the feedback coming.

W3C XML Schema(WXS) is asked for a lot too. Many, including me, wouldn’t mind having it in Qt. The big problem is that implementing it (properly) requires tons of work. Easily 10 K lines, and the test suite has about 40 K tests. While implementing it one typically becomes a sad, twisted old man unless one finds something divine. Anyone who’ve worked with the WXS, knows this is true.

So, what’s holding back WXS is that there currently are so many other interesting projects, like XSL-T 2.0 which should be relatively easy reachable, and more stuff on the XQuery front.

Though, the day I get to it, my idea is to implement it in such a way that the implementation has one validation automata, that both RelaxNG and WXS can be translated to. If it’s doable. Another idea is to implement WXS by rewriting schemata into XQuery queries. Likely not doable, but I haven’t concluded that yet.

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rusco:

XQilla is a nice project. If anyone would start an XQuery implementation today, one would consider joining one of the existing ones, naturally.

So, one reason is historical. Others are technical: in what way Qt can make use of XQuery(more on that in the future), and various system requirements such as code foot print and dependencies. While it’s not there yet, one might be able to squeeze Patternist onto mobile phones, for instance.

I think there’s room for XQilla and Patternist, and the usual sharing of experiences with folks like John Snelson through blogs & W3C is very useful. And I don’t mind a little healthy competition

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Nicolas:

No doubt that XML editors are shallow in the OSS community. I think the main reason to that have been the lack of stacks for core technologies like XQuery(although another reason is that XML tends to currently be a bit more heavy in the non-oss industry). Maybe it is because these stacks are rather heavy to pull up.

But this can change. With Qt being as central on Linux as it is, this is a great opportunity to literally distribute these stacks. In that way others can concentrate on building more user-centric things, with the help of a building block or two.

(XInclude and OASIS XML Catalogs are two other things that might see the light.)

To try and answer your request for comments/suggestions: I have not really been programming using XML, but it seems to me that schema (XML schema as a minimum, possibly also RelaxNG) support would also be a very good thing.
I have also been using xmlstarlet quite a lot to manipulate XML files from the command line and I’d suggest you take a look at it if you don’t know it already to get a feel of the kind of API that would be required… Xmlstarlet allows to query (Xpath only, not xquery as far as I can tell), transform, validate, edit (insert/update/suppress nodes and data) XML documents. It is already a pretty good start I guess I have not tried patternist so it is possible that it already does what xmlstarlet does… I’ll give it a try one of these days !

Thanks for your excellent work on XML in Qt/KDE and OSS in general,

But anyhow: Great news !