Subsetting with UBL and support in ebxml-msg

["Stephen Green" <stephen_green@bristol-city.gov.uk>]

Folks in ebMS

Greetings

I've not tried posting before so many thanks if I'm successful.

It seems time to resurface with my interest in payload
metadata declaration in a message header. With growing 
development of the need for subsetting of payload Schemas 
in UBL, for example, I'd like to just get some confirmation of
the encouragement I received earlier that there will be ample
means in ebMS 3 to declare use of not only a particular
set of Schemas in a document but also use of a particular
specified subset. 

We have come across in UBL the possible need to use not XSD
but a set of XPaths to define the subset without having to create
new namespaces. The set of XPaths and accompanying documentation
will likely be stored with a persistent url but will not be identified
with a namespace. There may or may not be some kind of urn
as an identifier of it though (haven't really got that far).

I gather this would be classed as metadata but how structured
would the metadata be allowed to be (and on the other side of the
coin, how flexible)?

Sorry I've not been able to glean this from drafts of specs but
I assume it is a bit of a moving target still.

I gathered too that ebMS 2 had support for this but will there
be any further support (if needed at all) in version 3?

My further interest will be in how the above facility would integrate
with specifications using the rest of ebXML but the message
header seems the main thing.

Apologies if I should have asked this on ebxml-dev.

All the best

Stephen Green