Mark,
One
thing I forgot to include in my original reply. There are two places
that BTP might be used. To coordinate calls among disparate, external
web services and to coordinate calls to XML based services within an
organizational boundry. The registration of sub-participants with
the root coordinator was being proposed as an optimization for the
latter.
If all Web Services are within the same domain (e.g., on the same LAN),
then there's no performance advantage, but I don't think there's much of a
performance disadvantage either in this world of modern, multi-threaded
operating systems. In addition, if multiple services happen to be co-located on
the same node as a subordinate coordinator then intra-node communication is
typically short-cut by the OS so that it doesn't go anywhere near the network.
(BTW, I'm assuming that a single organizational boundary is connected only be a
fast LAN, otherwise the communication performance argument comes back in.)
However, in the arena of a single organizational boundary I'd still say
that the separation of concerns, and isolation of business logic is important:
why should the root coordinator know about sub-participants? That's
implementation specific. Even within an organizational boundary, one department
may not trust all of the Web Services from another, and may not want root
coordination information to be propagated around the organization.
I would prefer us to keep things simple and have interposition as the
default, and if an application wants to register a service directly with the
root, then it can do it at the application level.
Cheers,
Mark.
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: Dr. Mark Little, Architect (Transactions), HP Arjuna Labs
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