Re: [xsl] Request help in understanding: node instance of schema-element(node)

[Eliot Kimber <ekimber@xxxxxxxxxxxx>]

Wendell Piez wrote:
> At 05:28 AM 1/27/2008, Mike wrote:
> > To be honest, even though Saxon does use xsi:schemaLocation for the 
> > limited
> > purpose of locating a schema once validation has been requested, I don't
> > think it's a good idea to use it. If you are validating a document then
> > that's probably because you don't trust it, and if you don't trust it, 
> > then
> > why should you trust its schemaLocation attribute?
>
> I agree with the conclusion here. The reasoning, however, does open a 
> deeper set of issues.
>
> In my experience, schemas (of whatever variety) have been used for two 
> purposes, which have historically been joined at the hip, but which are 
> actually quite distinct.
>
> One is "validation", which is to say, determine whether a document or 
> parts of a document conform to an expected or required type. ("Schema as 
> gauge.")
>
> The other is for type annotation or even for binding of XML data (which 
> natively takes the form of sequences of characters) to data types. 
> ("Schema as jig.")

I think there's an important third reason, schema-driven editing, where 
the schema is used by an editing tool to assist with creating XML 
documents. In that case schemaLocation is a convenience for binding a 
particular document to the schema to use to guide and constrain authoring.

Also, there is the important case of documents that have elements not in 
a namespace--in that case there is no better solution than 
schemaLocation for binding elements to their governing schemas. But I 
also agree that in that case schemaLocation is no better than a DOCTYPE 
declaration since you can't even check to see if the schema referenced 
matches the schema you have configured for use with a given namespace.

Cheers,

Eliot

--
Eliot Kimber
Senior Solutions Architect
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