XML Schema?

[Adam Logghe]

I haven't seen a Python schema validator yet.

I would think that if anyone would know it would be the XML-SIG mailing list
and the 4suite.org people.

4suite has the most complete standard XML toolset in Python I've seen yet,
I've been VERY pleased.

I suspect that Schema is not far enough along yet for serious
implementation??

Adam
adam in the domain devtty.net


"Harry George" <hgg9140 at seanet.com> wrote in message
news:m3ofw62blm.fsf at wilma.localdomain...
> Anyone have a python XML Schema parser/validator?  I thought I saw
> comments that it wasn't being done yet as part of xml-sig.  Of course,
> we don't actually need an XML Schema validator inpython (java or C++
> renditions would do fine), but there is a social cachet to it, so
> maybe worth the effort.
>
> Assuming it is an open task, here is an approach.  Anyone see holes in
> this, besides it being a humongous task?
>
> 1. Get the specs from OASIS-->W3C.
>
> 2. Get test cases (for schemas and for instances) There are a few
>    cases at xml-conf, but I think a lot more will be needed.  So I'll
>    need to generate them, and that suggests a case generator, plus of
>    course a test driver.  I have the testcase generator and driver
>    done.
>
> 3. XML Schema is basically a regular expression problem, with nodes as
>    the "characters".  So we can use classical lexer algorithms:
>    regexpr --> NFA --> DFA.  The hassles may be at the leaf nodes,
>    where XML Schema has lots of special cases.  I don't knbow if there
>    are non-re constraints in the specs, but if so I'd apply them after
>    the initial pass.
>
> 4. Given that state machine, run schemas through the parser until it can
>    build machines from valid schemas and detect invalid ones.
>
> 5. Given a sound state machine, run instance test cases through the
>    package until it is passing valid instances and detecting invalid
>    ones.
>
> 6. This would probably be an iterative enhancement exercise, once the
>    state machine engine was in place.
>
> I have a lex-workalike I wrote in Modula-2, which I'll use as the
> start point.  Probably could use a SAX input approach ("next node"
> instead of "next char"), maybe with 1 lookahead.
>
>
>
> --
> Harry George
> hgg9140 at seanet.com