A Discussion of Communication Schemes for Process Execution Histories to Enforce Entailment Constraints in Process-Driven SOAs

A distributed business process is executed in a distributed computing environment. In this context, the service-oriented architecture (SOA) paradigm provides a mature and well-understood framework for the integration of software services. Entailment constraints, such as mutual exclusion or binding constraints, are an important means to specify and enforce business processes in a SOA. Process engines control the process flow and are responsible for the coordination of the services that participate in a distributed business process. Since the enforcement of entailment constraints requires knowledge of the subjects and roles who executed particular task instances, we need to communicate the execution history of the respective tasks and processes between the services and the process engines. However, the inherent concurrency of a distributed system may lead to omission failures. Such failures may impair the enforcement of entailment constraints in a process-driven SOA. In particular, the impact of these failures as well as the corresponding countermeasures depend on the architecture of the respective process engine. In this paper, we discuss communication schemes for (distributed) process execution histories in a SOA. In particular, we provide generic procedures for different communication schemes and examine the efficiency of these schemes as well as their characteristics if omission failures occur. In this context, we especially consider if the respective process engine acts as an orchestration engine or as a choreography engine.