Additional authors: Rainer Krautter, debis Systemhaus Industry (Competence Center Document and Workflowmanagement) CU DMS, Erich-Herion-Strasse 13, D-70736 Fellbach, Germany. Email: Rainer.Krautter@debis.com). A Lightweight, Message-Oriented Application Server for the WWW Ralf-Dieter Schimkat (Supported by debis Systemhaus Industry) Wilhelm-Schickard Institute for Computer Science Sand 13 D-72076 Tübingen, Germany schimkat@informatik.uni-tuebingen.de Stefan Müller Wilhelm-Schickard Institute for Computer Science Sand 13 D-72076 Tübingen, Germany muellers@informatik.uni-tuebingen.de Wolfgang Küchlin Wilhelm-Schickard Institute for Computer Science Sand 13 D-72076 Tübingen, Germany kuechlin@informatik.uni-tuebingen.de Abstract: In this paper, we present a lightweight system that loosely couples and integrates any kind of source systems with information retrieval capabilities. The system provides mechanisms for a rapid integration of source systems into the World Wide Web (WWW), allowing the generation of configurable collections of individual, heterogeneous source systems. The proposed system is based on a lightweight, message-oriented application server and an object-oriented client framework to provide an uniform, Java-based graphical user interface. The system offers application middleware functionalities that solve issues such as limited bandwidth and scalability of both sides (WWW user clients and backend server systems) in a generic manner. Already integrated source systems include the system PROGRESS (a method base system for mathematical algorithms with functionalities for server-side computing) and SPECTO (an XML-based, distributed monitoring system). Keywords: Application server, uniform Web interface, application integration, message bus.   1 Introduction 2 Proposed Architecture 2.1 The Message Bus RESPONDEO - A Lightweight Application Server 2.2.1 Application Objects 2.2.2 Application Management Functionalities 2.3 The Client 3 Support Services 3.1 Scalability 3.1.1 WWW User Scalability 3.1.2 Backend Server Scalability 3.2 Bandwidth 3.3 User Interface 4 Examples The Integration of the Method Base System PROGRESS The PROGRESS Application Object and the PROGRESS Input Component 4.1.2 Initialization 4.1.3 Handling of PAOs Within the Client The Integration of the XML-based Monitoring System SPECTO 4.2.1 Initialization of SPECTO's Application Logic SPECTO's Offline Application Logic - EventDatabase 5 Summary 6 Acknowledgements References About this document ...