An implementation of optimistic policy for concurrency control in a computer network for real-time applications

In the field of real-time control systems, some attempts are in course to apply basic concepts of networking, data-base and transaction processing in order to provide a robust and efficient environment. This paper presents a simple implementation of a concurrency control mechanism in a computer network for real-time applications. This mechanism insures data-base integrity and consistency and provides a better performance with respect to locking in particular situations. The proposed mechanism is based on the detection of existing conflicts and their resolution before the beginning of the committing phase. Each transaction must verify its commit right before committing by performing a control on the statuses of shared objects. Fast transactions which update few objects are generally privileged over slow transactions which update many objects. Adding additional features to the basic mechanism, slow transactions are guaranteed to commit also in presence of concurrent fast transactions.