Re: [xml-dev] Versioning MicroXML (Was: MicroXML)

["Pete Cordell" <petexmldev@codalogic.com>]

Original Message From: "Liam R E Quin"
>> Taking ideas from various internet protocol negotiation schemes, can we
>> include a uxmldecl that includes a "require" attribute that lists 
>> features
>> the uXML parser must support.
>>
>> For example:
>>
>> <?uxml require="ns pi"?>
>
> As soon as you do that your spec no longer defines a single language,
> but 2^n languages, where n is the number of things you can write.
> It really hurts interoperability.

I disagree.  You end up with a single language that can be extended and is 
flexible.  There are internet protocols that do this type of thing every day 
and they a quite interoperable.  HTTP's Accept-*: headers is just one 
example of such negotiation.  At the end of the day people want their data 
to run with the widest set of resources, and so it's in their interest to go 
for the lowest common denominator.

> Language negotiation lets the server choose the single preferred value.
> So you only need n variants, not 2^n

> You did go on to say,
>
>> BTW - I think its important to agree that we are only looking for 3 or 4
>> widely implemented features, rather than 3 or 4 million!  If we have too
>> many then we lose interoperability.  Things analogous to XML namespaces 
>> and
>> xml:id that were added to XML after the initial release of XML are the 
>> sorts
>> of things we should be looking for.

>so, so far you've listed 3, and I can easily see a dozen more happening.
>comments
>lax error handling
>processing instructions
>namespaces, namespace path, external namespace definition files
>xml:base
>xml:id
>xinclude
>microschema, microentitydefinitions... :)
>mixed content and xml:space
>and so on and so forth
>
>Better to say, either use microxml or xml.
>
>XML succeeded largely because of the XML Promise -- every XML processor
>is licensed by the XML Specification to process any XML document.

I would argue then that the 'XML Promise' is a false promise!  Does the XML 
Promise include XML namespaces?  Does it include parsing of external DTDs? 
Does it include parsing of XInclude?  Does it include parsing of xml:id?  I 
think not.  If you rely on these features you currently have no way to 
express it in XML 1.0 and you're left with trying to convince yourself that 
these things are usually OK.  That's why we have 
http://www.w3.org/TR/xml-proc-profiles/.

Pete Cordell
Codalogic Ltd
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