The Activity Service

Recently I wrote an article with Bruce Martin about the J2EE Activity Service. In essence, what we show is that ACID transactions aren't sufficient for everything and there are a number of extended transaction models that allow for the controlled relaxation of the ACID properties. What this means is that one size doesn't fit all and as usual it is necessary to use the right tool for the right job. Anyone who's worked in the area of (distributed) transactions for a while will typically have a story or two to tell about where ACID transactions were shoe-horned into areas they simply weren't suitable for.

Therefore, rather than provide support for a single model, we did work with IBM, IONA Technologies, Bank of America, Alcatel and others in the OMG on the Additional Structuring Mechanisms for the OTS. This defines an infrastructure to support a wide range of extended transaction models. The architecture is based on the insight that the various extended transaction models can be supported by providing a general purpose event signaling mechanism that can be programmed to enable activities (application specific units of computations) to coordinate each other in a manner prescribed by the extended transaction model under consideration.

Once this was adopted within the OMG, IBM, ourselves and others moved to push this into J2EE via JSR 95: the J2EE Activity Service. This has recently been finalised and presumably will become part of some future version of J2EE.

Now whether or not this work will actually change the way people develop transactional applications in J2EE is open to debate. I know that when we were doing the work it seemed "obvious" that this was the future of transactions and alongside IBM we've had some interesting development experiences. But the world has moved on since 1997 and I often have interesting discussions with Greg and others as to whether the Activity Service is of much use. Only time will tell.

However, what cannot be in doubt is the influence this work has had elsewhere. Since the original OMG work was released, it has influenced the WS-Coordination specification from IBM, Microsoft and BEA, as well as the WS-Coordination Framework from ourselves, IONA, Oracle, Sun and Fujitsu. It also formed the basis of our initial submission to the OASIS BTP technical committee back in 2001; though its influence after that point was mimimal.

In some ways the new OASIS WS-CAF architecture, which factored context our of the original Activity Service, is a purer form of the model we were trying to achieve back then.