Re: New XSL Optimization

At 02:55 PM 6/25/99 -0400, Jonathan Borden wrote:
>    This is an excellent article and raises several important issues. One
>that struck me is in regards to the question of validating transforms, e.g.
>that the result of an HTML -> HTML transform is valid against the HTML DTD.
>Paul notes that because such transforms are frequently carried out via
>turing complete general purpose languages, that such validation is
>impossible. I wonder what the effect of being side-effect free has on the
>ability to determine whether a result set conforms to a schema? Agreed,
>since XSL is "Turing complete" it is not possible to determine the general
>correctness of XSL programs, for example whether such programs will have
>infinite loops etc. Might it be possible to verify a restricted set of
>conditions?

Validating transforms was part of the motivation that drove me to write
"Toward A Layered Model for XML" (  )  It seems like being able to validate
transformed or composed documents (whatever mechanism was used) against a
schema without having to serialize the internal structure back to an XML
document and reparsing would be a good idea.  So far, I haven't seen a
validator that reads a SAX or DOM input and compares it to a DTD, and
haven't had time to write my own.

You ask a tougher question about being able to validate results through
checking the XSLT itself - that, I suspect is a _lot_ more difficult, even
if you have the schema of the original document to be transformed.  (Run it
through multiple consecutive transformations and it could get even more
interesting.)

Simon St.Laurent
XML: A Primer / Building XML Applications
Inside XML DTDs: Scientific and Technical (July)
Sharing Bandwidth / Cookies
http://www.simonstl.com


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