Heteroqeneous Transactions and Recursive Atomicitv

Today computing environments are often composed of heterogeneous subsystems like mainframes, workstations and personal computers. The various subsystems typically use database systems with different transaction models. For such subsystems to cooperate smoothly it is necessary to have a precise understanding of each other's transaction models. In particular, a TP-monitor trying to coordinate transactions of subsystems needs precise models of the transactions offered by these underlying subsystems. This paper introduces nondeterministic, atomic ccmputing primitives which are used to construct A-nets for describing transaction models precisely. A-nets and the computing primitives can be applied recursively to describe transactions at arbitrary levels of refinement. The techniques are demonstrated by describing a number of wellknown and widely used transaction models, in particular ACID-transactions, distributed transactions with 2-phase commit, Sagas, and LU6.2 transactions.