ebBPSS: Choreographing transitions between business transactions inmultiparty collaboration

[Pim van der Eijk <pvde@multiweb.nl>]

I'm working on a an example for ebBPSS and have some difficulty
understanding the specification on the issue of choreographing
transitions between business transactions in a multiparty
collaboration.

The ebBPSS DTD allows <Transition> within <BinaryCollaboration> and
within <BusinessPartnerRole>.  I assume the former are intended to
encode transitions within business states in the scope of the specific
<BinaryCollaboration> and the latter for global transitions.   The
dropshop sample uses them for this purpose.

Is this correct?

If so, what is the semantics of attaching <Transition> elements as
daughter nodes of particular <BusinessPartnerRole>s rather than
others?  Does this mean that the <BusinessPartnerRole> must be
involved in the source or target business state or is this irrelevant?

In my application, I would like to <Fork> at the multiparty level, to
perform a number of <BinaryCollaboration>s, involving different
parties, in parallel, then <Join> back. Is this possible with ebBPSS?
<Fork> and <Join> are only allowed within <BinaryCollaboration>s.

With the current DTD, I could put the <Fork> as last state in the
<BinaryCollaboration> before the parallel branches, and a <Join> as
first state in the first <BinaryCollaboration> after the parallel
branches, and a <Transition> at the multiparty level.

Is this the way to do this?

Can someone elaborate on the decision not to allow <Transition>,
<Fork> and <Join> as allowed content for <MultiPartyCollaboration> ?

Regards,
Pim van der Eijk