XML Schema and conformance requirements

[Juan Carlos Cruellas <cruellas@ac.upc.es>]

Dear all,

During these last days we have been exchanging some emails dealing mainly
with 
the issue of enveloping parts of the input documents and whether to allow
the possibility
of including explicit requests for different types of time-stamps,
according to Ed's proposal...

I still think that it could be useful to develop a XML schema complete
enough as to allow 
those requesters that do not find a profile matching their needs to manage
their problem.
Nevertheless, we could define in our standard a set of CONFORMANCE
REQUIREMENTS for the
"core protocol" that will establish that those elements that  
are seen as unnecesary when an application profile 
can be defined, WILL NOT APPEAR.

In other words, we could define a XML Schema that could accomodate both
situations,
those where the service provider has defined an application profile and
those where a requester
does not find adequate those application profiles and wants to request
additional functionality.
It would be like defining signing requests of "different levels", being the
lowest one the core, ie,
those where there  is not much freedom for the requester....
Advantages of this approach? 

It is true that the XML schema will be larger than one only satisfiying the
situation of "almost everything in the application profile", BUT in fact,
the applications will be
as simple as those that would be developed following the xml schema of the
"almost everything in the application profile",
because in the end, the elements in this case would be almost the same.

In addition, if we assume that there can be situations where some requester
needs things that are not
in the application profile defined by the service provider, we also are
able to manage these situations.

Regards

Juan Carlos.