RE: DTDs in CPIM-03 (was RE: draft-ietf-impp-cpim-03)

> Yes, Scott, I believe this was what I was thinking of. Though 
> I'm curious -
> does your draft make any recommendation about using DTDs vs. 
> XML Schemas? I
> remember from somewhere that the Apps ADs had expressed a 
> preference for XML
> Schemas over DTDs. I note that from a consistency perspective 
> the PIDF draft
> uses XML Schemas rather than DTDs.

Well, my co-authors and I started out with a specific suggestion to use XML
Schema in the absence of requirements to do something else, but that drew
the ire of a few folks who took issue with some of the shortcomings of XML
Schema and had preferences for RELAX NG or Schematron (if those don't mean
anything to you, don't worry).  The "XML community" is still working through
the issues, so we weren't able to reach consensus on any single approach.
The best we could do is describe the alternatives and provide guidelines to
help designers pick the specification language that meets their needs.

I don't think there's anything in CPIM that can't be handled by XML Schema,
with the primary advantage over a DTD in this situation being the ability to
more narrowly define data types and extensibility mechanisms.  XML Schema
helps provide a more definitive protocol specification that can be processed
automatically to a greater level of detail by a validating parser.  It does
tend to be more verbose than a DTD, but it also tends to be easier for a
human to read and understand.

-Scott-



  [reminder: [email protected] for non-technical discussions, please]