online conversion support from xsd to rng?

[joakim]

It occurred to me that the Nxml mode in Emacs isn't as useful as it could
be. Nxml supports rng schema descriptors(relax ng). Xml files are usually
described by xsd files such as this one:
http://maven.apache.org/xsd/maven-4.0.0.xsd.

So, if I could convert a xsd to a rng on the fly, I could immediately
have function completion and validation on a number of xml documents. 

James Clark(the original author of the nxml mode) wrote a utility called
Trang: http://www.relaxng.org/#conversion

This could presumably be run online somewhere and provide the needed
service for Emacs, more conveniently than having to install the program
locally. (Trang is a free software Java program compilable with GCJ)

This raises a number of questions:

- do we want Emacs to have this type of facility at all? (I would say
yes, provided we solve a number of problems)

- how do we ensure this backend(and future other backends) are free
software?

- what would the backend interface look like? Maybe we could generate
ELPA packages on the fly?


-- 
Joakim Verona