Re: Chameleon components

On 2/20/07, Norman Walsh <Norman.Walsh@sun.com> wrote:
>
> / Jeni Tennison <jeni@jenitennison.com> was heard to say:
> | I think it's a mistake to bundle multiple applications into a single
> | component (i.e. have "p:transform" and "p:validate" steps) because
> | they have completely different interfaces. XSLT 1.0 produces a single
> | result document; XSLT 2.0 produces many. RELAX NG can check "plausible
> | validity"; XSD takes multiple schema documents; Schematron has a
> | 'phase' parameter; and so on.
> |
> | We will end up with a situation where we have huge numbers of optional
> | parameters, parameters that are ignored in certain circumstances,
> | inputs that must have only one document if a particular application is
> | specified and so on. In other words, lots of constraints that can only
> | be expressed through fairly complicated natural language.
> |
> | We will also end up having components whose definitions will have to
> | change as new schema and transformation languages emerge. For example,
> | "p:validate" will have to handle XML Schema 2.0 at some point. I think
> | this will cause big headaches.
>
> Exactly. I'm in complete agreement with Jeni.



I hadn't imagined that we would have a 'p:transform' component and so a
p:validate that handles all the different possible schema languages out
there is probably not what I'd prefer.

In the case of XSLT, I had imagined that we'd want to allow the author
to configure:

   * which version of XSLT
   * how the transform is invoked.

In the case of XML Schema, we have the same configuration need--especially
given that XML Schema 1.1 will be arriving about the time we're done.

So, given that, we need to consider components like:

   * p:xslt that handles XSLT 1.0 and XSLT 2.0
   * p:xmlschema that handles XML Schema 1.0 and 1.1
   * p:relaxng
   etc.




-- 
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics