Extensible Composable Choreographies Use Case

One piece of work that Commerce One has done is to identify the different
document exchange patterns (i.e. choreographies) that businesses follow when
placing an order [1]. This highlights several potential requirements on
choreographies:

1. That the identical message can be used in multiple different
choreographies, for example there are three choreographies that can be used
to send an order:
  i) Send just an order
  ii) Send an order and receive a single order resposne
  iii) Send an order and receive multple order responses
In all the choreographies there is just one order message definition and one
order response order definition. Also note that the second instance is a
simple extension of the first, and third a simple extension of the second.
So perhaps there is a requirement that chorography definitions should be
extensible to avoid duplication.

2. That choreographies are composable. For example after any of the three
choreographies described in '1', you can have another three choreographies:
  i) Send a Change Order
  ii) Send a Change Order and receive a single change order response
  iii) Send a Change Order and receive multiple change order responses
So there are now theoretically 12 different permuations of how to place and
optionally change an order - although in practice they are usually more
limited.

3. You can then, optionally follow these combinations by a cancel order or
precede them by a price check query which results in a binding price to be
used in the order. This leads to even more possible permutations.

So the requirement from this use case is to be able to allow choreographies
to be: a) composed of other choreographies; and b) an extension of another
choreography; in a way that allows those combinations and extensions to be
defined in a simple way.

David

[1] http://www.xcbl.org/DevResources/BusinessTransactions.html

Director, Product Management, Web Services
Commerce One
4440 Rosewood Drive, Pleasanton, CA 94588, USA
Tel/VMail: +1 (925) 520 4422; Cell: +1 (925) 216 7704
mailto:david.burdett@commerceone.com; Web: http://www.commerceone.com