The Mentor-lite prototype has been developed within the research project "Architecture, Configuration, and Administration of Large Workflow Management Systems" funded by the German Science Foundation (DFG). In this paper, we present the architecture of Mentor-lite and our approach towards customizability. The feasibility of the presented approach is shown.

The Mentor-lite prototype has been developed within the research project “Architecture, Configuration, and Administration of Large Workflow Management Systems” funded by the German Science Foundation (DFG). It has evolved from its predecessor Mentor [1], but aims at a simpler architecture. The main goal of Mentor-lite has been to build a light-weight, extensible, and tailorable workflow management system (WFMS) with small footprint and easy-to-use administration capabilities. Our approach is to provide only kernel functionality inside the workflow engine, and consider system components like history management and worklist management as extensions on top of the kernel. The key point to retain the light-weight nature is that these extensions are implemented as workflows themselves.

Workflow management systems (WfMSs) support the efficient, largely automated execution of business processes. However, using a WfMS typically requires implementing the application's control flow exclusively by the WfMS. This approach is powerful if the control flow is specified and implemented from scratch, but it has severe drawbacks if a WfMS is to be integrated within environments with existing solutions for implementing control flow. Usually, the existing solutions are too complex to be substituted by the WfMS all at once. Hence, the WfMS must support an incremental integration, i.e. the reuse of existing implementations of control flow as well as their incremental substitution. Extending the WfMS's functionality according to future application needs, e.g. by worklist and history management, must also be possible. In particular, at the beginning of an incremental integration process, only a limited amount of a WfMS's functionality is actually exploited by the workflow application. Later on, as the integration proceeds, more advanced requirements arise and demand the customization of the WfMS to the evolving application needs. In this paper, we present the architecture and implementation of a light-weight WfMS, coined Mentor-lite, which aims to overcome the above-mentioned shortcomings of conventional WfMSs. Mentor-lite supports an easy integration of workflow functionality into an existing environment, and can be tailored to specific workflow application needs.

MENTOR (“Middleware for Enterprise-Wide Workflow Management”) is a joint project of the University of the Saarland, the Union Bank of Switzerland, and ETH Zurich [1, 2, 3]. The focus of the project is on enterprise-wide workflow management. Workflows in this category may span multiple organizational units each unit having its own workflow server, involve a variety of heterogeneous information systems, and require many thousands of clients to interact with the workflow management system (WFMS). The project aims to develop a scalable and highly available environment for the execution and monitoring of workflows, seamlessly integrated with a specification and verification environment.

Enterprise-wide workflow management where workflows may span multiple organizational units require particular consideration of scalability, heterogeneity, and availability issues. The Mentor project, introduced in this paper, aims to reconcile a rigorous workflow specification method with a distributed middleware architecture as a step towards enterprise-wide solutions. The project uses the formalism of state and activity charts and a commercial tool, Statemate, for workflow specification. A first prototype of Mentor has been built which allows executing specifications in a distributed manner. A major contribution of this paper is the method for transforming a centralized state chart specification into a form that is amenable to a distributed execution and to incorporate the necessary synchronization between different processing entities. Fault tolerance issues are addressed by coupling Mentor with the Tuxedo TP monitor.