Bisimulations for Communicating Transactions

We develop a theory of bisimulations for a simple language containing communicating transactions, obtained by dropping the isolation requirement of standard transactions. Such constructs have emerged as a useful programming abstraction for distributed systems. In systems with communicating transactions actions are tentative, waiting for certain transactions to commit before they become permanent. Our theory captures this by making bisimulations history-dependent, in that actions performed by transactions need to be recorded. The main requirement on bisimulations is the systems being compared need to match up exactly in the permanent actions but only those. The resulting theory is fully abstract with respect to a natural contextual equivalence and, as we show in examples, provides an effective verification technique for comparing systems with communicating transactions.