Semantic based concurrency control of open nested transactions in active object oriented database management systems
Active object oriented database management systems (AODBMS) are finding increasing application in different application domains and especially for cooperative and long duration activity management. In this paper, we propose a concurrency control mechanism for open nested transactions in an AODBMS. It exploits the semantics of the transactions to achieve controlled cooperation and concurrency among the transactions. Atomic AODBMS transactions are treated as base transactions. A complex transaction type is formed from a collection of base and complex transactions, a set of detached mode ECA rules and a state transition model. The cooperation semantics of a complex transaction type with other complex transaction types is specified by associating with each state of a complex transaction, a set of cooperating complex transaction types. The abort semantics of a complex transaction type is specified by means of compensating base transactions. We define a correct class of schedule called CoopComp-schedule which satisfies the state transition semantics of the individual complex transactions and also maintains the cooperation and compensation semantics of the individual complex transactions within the generated schedule. A concurrency control scheme called NP-QuadLock for generating only CoopComp-schedules has been provided. The proof of correctness of the proposed concurrency control mechanism is also given.
concurrency control active database object oriented systems