A Correctness Criterion for Transaction Management in Loosely Coupled System

At present, most distributed system are loosely coupled. They are usually composed of components by invocation temporarily. Their components are often autonomic and execute independently. As to concurrency control, parallelism in there systems are more than in traditional distributed ones. So that serializability is too strict a correctness criterion to them. This paper divided transactions into atomic units according to semantic information. And interleaving between atomic units of different transactions is permitted to heighten parallelism. This newly proposed correctness criterion is named as weakly serializability. Weakly serializable schedule is non- serializable, but preserves data consistency at a higher level of semantics. Necessary and sufficient Condition of Weakly serializable schedule is presented and proved. Accordingly a distributed algorithm for concurrency control is given also.