Specification of Distributed Information Systems

The specification, development and use of distributed information systems is an important research area with many practical applications. Examples for existing such systems are those owned by banks, airlines or governments. Moreover, the explosive growth of the Internet is evidence that a global information structure is developing, and expansion in the use of large distributed information systems can be predicted. Information systems are reactive systems. Unlike transformational systems—that is, systems whose function is to transform some inputs into output results—reactive systems have an unlimited number of interactions with their environment. Basic notions of program correctness do not apply, and techniques for designing transformational systems do not easily carry over to reactive systems. Non-distributed reactive systems, like conventional operating and database systems, are not easy to design, implement and restructure, a lot remains to be done to develop helpful high-level concepts, features, languages, methods and tools. However, existing products can already cope successfully with reasonably complex systems in practice. Formal methods from logic, algebra and process theory have been successfully applied, for instance in query and transaction processing, but they are not in general standard engineering practice yet. Distributed reactive systems are still an order of magnitude more complex and difficult to specify, analyse, implement and reconfigure. They are not well understood, and methods for designing, implementing and reengineering them have not yet reached a level of mature and sound engineering practice. A great challenge is to cope with concurrency, synchronization, and communication at an appropriate level of abstraction. This can be achieved by applying concepts from concurrency theory for distributed information systems. This seminar was the follow-up of the Dagstuhl Seminar 98071 " Information Systems as Reactive Systems " , which took place in February 1998. Until that seminar, there was little interaction between the communities concerned with information systems and concurrency theory. One outcome of the seminar was that there is a definite need for interaction; new contacts have been established. The focus of the present seminar was again to bring experts from the respective fields together. In contrast to the previous seminar , we put even more focus on applications, seeing the design of distributed information systems not only as theoretically challenging but also as an engineering problem. In particular, the following topics have been addressed: 1 • Modelling and design methods. Information systems involve data, objects and global processes. In conceptual mod-eling, these aspects have been addressed …