Ablaufkontrolle von Prozess-Choreographien

Today, service-oriented architectures (SOA) can be used for supporting the implementation of cross-organizational workflows with autonomous and heterogeneous participants. In this context, the concept of choreographies is well established, introducing a new viewpoint on interacting services. A choreography model describes interactions from the perspective of an ideal observer who is able to see all interactions and their flow and data dependencies. If all participants adhere to a choreography model, no centralized workflow coordinator is required because every participant knows how to react on messages due to the choreography model. Nevertheless, the question how to assure that participant abide the choreography model and behave like specified in beforehand remains and thus, if the process integrity constraints are met during run time. Challenging is the autonomy of participants in a crossorganizational setting und therefore that only non-intrusive monitoring techniques can be considered where no new software can be installed or changed at the participants side. This work therefore provides a new approach in order to monitor the observable behavior of choreography participants and to verify choreography integrity constraints and their violation during run time. At first, this work will therefore introduce the required sensors and their corresponding infrastructure and will also introduce a basic mechanism for detecting integrity constraint violations during run time. This will be underpinned by a formal model based on the event calculus. The calculus allows for detection deviations from normal choreography conditions by temporal reasoning and therefore allows for detection of process integrity constraints violations at run time. The introduced approach is not only able to handle message based integrity constraints, but also able to handle interaction requirements like time constraints, requirements for single choreography instances like the control flow constraints and also cross choreography instance based constraints, which the participants have to abide in order to successfully run the choreography. Are process integrity constraint violations detected by the approach developed within the first part of this work, the question how to solve integrity violations remains. Within this work, a recovery approach based on the transaction concept is introduced which is able to include the verification results directly into transactional activity control. The concept presented extends traditionally known protocols by a coordinator which is able to decide autonomously if a transaction is able to finish successfully by using rules. Traditionally, a transaction initiator is the participant deciding about the outcome of a transaction. In practical choreography situations there is not always an initiator who is able to decide about all participants. In addition, the presented approach is also able to use the verification results for transactional activity control and is therefore able to support choreography recovery in the case of process integrity constraint violations.