Re: interposition requirements

[Mark Little <mcl@arjuna.com>]

 

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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SENDER : Dr. Mark Little, Architect (Transactions), HP Arjuna Labs
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