Abstract 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 demo will show the feasibility of the presented approach. 1 System Overview The Mentor-lite prototype has evolved from the Mentor workflow management system [4, 5], but aims at a simpler architecture. The main goal of Mentor-lite has been to build a light-weight, extensible, and tailorable system 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. An invocation interface for application programs is provided by a generic IDL interface on the engine side and specific wrappers on the application side [3]. As shown in Figure1, the basic building block of Mentor-lite is an interpreter for workflow specifications. In Mentor-lite, workflows are specified in terms of state and activity charts, the specification formalism that has been adopted for the behavioral dimension of the UML industry standard and was already used in Mentor. Two additional components, the communication manager (ComMgr) and the log manager (LogMgr), are closely integrated with the workflow interpreter. All three components together form the workflow engine. The execution of a workflow instance can be distributed over several workflow engines at different sites. A separate workflow log is used at each site where a Mentor-lite workflow engine is running. Databases like the workflow repository (i.e., a repository of workflow specifications) or the worklist database can be shared by Mentor-lite workflow engines at different sites. 2 Implementation Details The workflow specifications are interpreted at runtime, which is a crucial prerequisite for flexible The Mentor-lite Prototype: A Light-Weight Workflow Management System Jeanine Weissenfels, Michael Gillmann, Olivier Roth, German Shegalov, Wolfgang Wonner University of the Saarland, Germany E-mail: {weissenfels,gillmann,roth,shegalov,wonner}@cs.uni-sb.de WWW: http://www-dbs.cs.uni-sb.de Wrapper Application Program Workflow Interpreter ComMgr LogMgr Workflow Engine 1 Workflow Engine 2 Workflow Engine n Workflow Logs A P P L. I N T E R F A C E Worklist Database Workflow Repository Extensions are Workflows ! History Mgmt Workflow Spec. Worklist Mgmt Wrapper Application Program Wrapper Application Program Wrapper Application Program Wrapper Application Program Figure 1: The Mentor-lite architecture