Hilmar Schuschel

Triggering Replanning in an Integrated Workflow Planning and Enactment System

Workflow management systems support and automate the enactment of business processes. For this purpose, workflow management systems use process definitions that have been manually planned and modeled at build time. Recent research approaches try to enhance this concept by automating the creation of process definitions, using planning algorithms. This avoids the need for predefined process definitions and thus increases flexibility and allows to save costs. An important aspect of flexibility is the ability to react to unanticipated events that might occur during runtime. This Reaction can imply replanning and dynamically adapting the process. This paper shows how replanning can be triggered automatically in an integrated workflow planning and enactment system. Triggers for monitoring process executions are presented and events are defined which lead to the evaluation of corresponding conditions for deciding when replanning is necessary. Finally, advantages, limitations and areas of application of this approach are discussed.

Integrated Workflow Planning and Coordination

Two major tasks in process management are the planning of a process and the coordination of its execution. Workflow management systems support and automate the coordination of a process, but planning the process remains a manual task. This paper argues that planning and coordination are closely interrelated and therefore restricting the attention to the automation of coordination can lead to problems concerning consistency and performance. A concept is presented to avoid these problems by adding automated planning. It is shown how planning algorithms from Artificial Intelligence can be combined with workflow management concepts to build an integrated workflow planning and coordination system. Advantages, limitations and areas of application of this approach are discussed.

Dynamic failure recovery of generated workflows

An important research area in the workflow management domain is the adaptation of workflows to unexpected events or failures at runtime. In this paper we present a concept for dynamic and automated workflow re-planning that allows to recover from such failures. To handle the complex dynamic situation of a partially executed workflow, we propose a multi-step procedure that includes the termination of failed activities, the sound suspension of the workflow, the generation of a new process definition, and the adequate process resumption. An important aspect of the presented re-planning procedure is that all steps including the generation of a new process definition are fully automated.

Automated planning in a service-oriented architecture

Service-oriented computing is a new paradigm to improve the performance of information systems in environments demanding for flexibility and interconnectivity. Additionally, the support of intra- and inter-organizational processes has become crucial for the competitiveness of companies. Recent research approaches propagate to plan processes automatically to improve quality and flexibility. This paper discusses the application of AI planning for service composition in a service-oriented architecture. Three alternative levels of abstraction for service descriptions are defined and their impact on automated planning is investigated in regard to the provider and requestor role of service composers. It is shown that different abstraction levels of service descriptions are necessary to take full advantage of AI planning in a service-oriented architecture.

Objektorientierter Entwurf eines flexiblen Workflow-Management-Systems

Zusammenfassung. Dieser Beitrag enthält die wesentlichen konzeptionellen Überlegungen zur Entwicklung eines flexiblen Workflow-Management-Systems. Ausgehend von einer Diskussion möglicher Modellierungsalternativen wird unter Verwendung objektorientierter Modellierungstechniken ein Workflow-Meta-Schema entwickelt, das die relevanten Entitäten klassifiziert und ihre Beziehungen abbildet. Anhand eines Beispiels werden die getroffenen Entwurfentscheidungen ausführlich begründet. Schließlich werden Zustände und Zustandsübergänge von Workflow-Instanzen beschrieben, und es wird diskutiert, wie dynamische Veränderungen von Workflows zur Laufzeit durchgeführt werden können, um laufende Workflows dynamisch an veränderte Umweltbedingungen anzupassen.Abstract. This contribution discusses the conceptual design of a flexible workflow management system. After discussing a set of modeling alternatives, a workflow meta schema is developed, using object oriented design principles. We describe how workflows are modelled and executed. Key design decisions are validated using a sample workflow model and a sample workflow instance based on that model. We propose a state transition diagram for workflow instances, and we discuss how dynamic modifications of workflow models can be conducted to adapt running workflow instances to changes in the workflow environment.