New model and scheduling protocol for transactional workflows

A transactional workflow is composed of traditional flat transactions, and its execution has relaxed transactional atomicity. Due to different termination characteristics of transactions, a transactional workflow may be not well-formed. Moreover, only one workflow is allowed to execute a non-compensatable transaction with the current scheduling protocol. We present a transactional workflow model and formally define the correctness criteria of transactional workflow structure (well-formedness) and execution (serializability). We then propose an efficient method for well-formedness validation through a set of computation rules. Finally a scheduling protocol based on two kinds of locking granularities is presented. The protocol is different from related research in the fine-grained locking on transaction instances and coarse-grained locking on transaction classes, multiple workflows are therefore allowed to execute non-compensatable transactions if they are not conflict in a predicated future execution.