Concurrency and forward recovery in atomic actions

Some difficulties and complexities in atomic actions occur only when the concept of atomic actions is extended to allow concurrency within atomic actions and to allow a single atomic action to execute at a number of different sites. Also, providing facilities for both forward and backward recovery presents problems not found in the more usual case of allowing only backward recovery. The author presents an analysis of these problems and proposes a general structure for a solution. A syntax which might be used to specify this structure is also given and illustrated with examples. The practicality of the scheme is justified by sketching one possible implementation.