[XML-SIG] WSDL library ?

[Paul Prescod]

Rich Salz wrote:
> 
> ...
> 
> > Of course it should be possible to refer to an XML schema for
> > *document-oriented* SOAP. But for RPC-oriented SOAP, older IDLs are
> > actually much simpler.
> 
> DCE IDL; it's an ISO standard. :)

I hate to say it but I've never really had any problem with IDL. I don't
see the benefit in inventing an angle-bracket syntax for it just to have
done so.

>...
> >  2. The interface description language should be as easy to read and
> > write (semantically, not syntactically) as standard IDLs like CORBA and
> > COM IDLs. There is a sense that WSDL is much, much more complicated and
> > this is going to hurt its adoption on the open Internet.
> 
> You wanna get rid of the "abstract" layers?

Er, If I'm going to use SOAP as a replacement for CORBA/DCOM, I'd like
the abstract layers to be as abstract as IDL and no more and no less.
Right now they seem both more and less. They are less abstract in that
they are defined in XML schema which is fundamentally a language for
defining XML vocabularies, not "abstract data models." They are MORE
abstract in the sense that if you point out the problems of XML schema
in this area people will say: "don't think of it as directly specifying
the XML elements. Think of it as an abstract definition language." Only
it is so hard to think of an XML vocabulray definition language as an
abstract data typing that it makes my head hurt and you almost have to
mentally indirect through IDL.

> >  3. If the interface definition language is to be used both for RPC
> > *and* document-style interfaces then it needs first-class concepts of
> > array and struct, which XML Schema lacks, for RPC-style interfaces.
> > Arguably, using schema for both kinds of interfaces is more confusing
> > than helpful.
> 
> Not sure what we could do.

Well I know it would never go over but to me IDL is already a decent
abstract interface definition language. What does XML Schema provide for
that purpose beyond buzzword compliance.

Of course XML Schema is much more appropriate for defining the syntax of
*document-style* messages. But they are a very different kettle of fish.
They are defined by their syntax, not their "abstract model."

Heck, maybe XML schema is even good for defining the *syntax* (not data
model) of RPC messages. You could somehow refer from the schema up to
the abstract definition to say which elements represented which
parameters and structure properties.

You know CORBA etc. What's wrong with IDL other than being
unfashionable?

 Paul Prescod