xml-dev - RELAX to ISO

[Rick JELLIFFE <ricko@geotempo.com>]

I was pleased to see the xmlhack story that RELAX is submitted for ISO
fast-tracking to become a technical report. 

Congratulations to Murata-san and the others involved.

I strongly believe that, because every schema language is made by
weighing tradeoffs and with particular uses and design philosphies in
mind, there is substantial benefit to the community in having different
schema languages available.  The feature that one markup language omits
may be the one you need sometime.  Which is not to deny the
network-effect benefits of standardizing on particular schema languages.

I think RELAX's strength is in content model issues and evolvability,
while XML Schema's strength is in fine-grained datatyping, identity
constraints and wildcarding.  So RELAX may be most useful for idiomatic
human-oriented markup languages, which XML Schemas could be more useful
for completely specifying data interchange formats.  (I am sure others
will have legitimate views that are different. I am very interested in
hearing other
opinions on this.)

People who are intimidated by XML Schemas (or, at least, by the material
currently available to explain XML Schemas) may find RELAX more
approachable.  For example, you could convert your existing DTD to RELAX
to gain simple datatype validation, add Schematron schemas for more
co-occurrence constraints, and then plan to convert from RELAX to XML
Schemas when you become comfortable that XML Schemas is worth it.

At this stage in the game, don't trust: try :-)


Rick Jelliffe

Developer, Schematron schema language;
Member, W3C XML Schema WG (not in that capacity);