Modelling coordination and compensation

Transaction-based services are increasingly being applied in solving many universal interoperability problems. Exception and failure are the typical phenomena of the execution of long-running transactions. To accommodate these new program features, we extend the Guarded Command Language [10] by addition of compensation and coordination combinators, and enrich the standard design model [15] with new healthiness conditions. This paper shows that such an extension is conservative one because it preserves the algebraic laws for designs, which can be used to reduce all programs to a normal form algebraically. We also explore a Galois link between the standard design model with our new model, and show that the embedding from the former to the latter is actually a homomorphism.