I just have one major comment ...
As I've stated here before, I can see no reason why "callout" receives
any mention in an architectural document. Callout is an implementation
detail, where an OPES entity determines that it needs to go elsewhere to
accomplish its task. Furthermore, not only do I not see a need to
*identify* a callout protocol, I don't even see a need to standardize on
one. The important interface is the one between entities, such as that
provided by HTTP, or other transfer protocols. If you need to "callout"
to a service, give it an HTTP interface and call it an entity. This is
how things work today with HTTP intermediaries (firewalls, caches,
From a practical point of view, this additional hop introduces
unnecessary latency, when that processing could easily be done by the
entity within the flow.
Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
Ottawa, Ontario, CANADA. distobj(_at_)acm(_dot_)org