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Current wireless sensor network (WSN) architectures are based on the assumption that all sensor nodes are participating in a single global task. In many scenarios, however, it will be desirable to use a single sensor network for multiple concurrent applications. In order to enable such multipurpose WSNs efficiently, delimiting each application to its(More)
Massively Multiplayer Online Games (MMOGs) are a risky business: while they offer potential profits beyond those of conventional computer games, they also require costly investment in the necessary hardware infrastructure. In nearly every MMOG today, these costs come from the use of a Client/Server architecture where the load of possibly hundred thousands(More)
Many interesting application systems, ranging from work-flow management and CSCW to air traffic control, are event-driven and time-dependent and must interact with heterogeneous components in the real world. Event services are used to glue together distributed components. They assume a virtual global time base to trigger actions and to order events. The(More)
Publish/subscribe (pub/sub) middleware facilitates loosely coupled cooperation and fits well the needs of spontaneous, ad-hoc interaction. However, newly started mobile applications have to be bootstrapped to interpret the current flow of notifications correctly and commence normal operation. This problem is aggravated in mobile environments where(More)
Applications ranging from event-based supply chain management to enterprise application integration and pervasive computing depend on the timely detection and notification of events. We present Cream the event-based reactive component of the Dream middleware platform. Here we address four key issues in distributed and heterogeneous environments: event(More)
Auctions have been a popular trading paradigm for centuries but have gained new interest through worldwide trading on the Internet. Many B2C sites are embracing reverse auctions as an additional service to registered customers. In all these cases the efficient notification of the participants is essential. In this paper we develop the notion of a(More)
This demo combines active DB technology in open, heterogeneous environments with the Web presence requirements of nomadic users. It illustrates these through profiling of users and Internet-enabled vehicles. A scenario is developed in which useful functionality is provided , such as instrument adjustments, maintenance and diagnostic information handling(More)
The existing Web service flow (WS-flow) technologies enable both static and dynamic binding of participating Web services (WSs) on the process model level. Adaptability on per-instance basis is not sufficiently supported and therefore must be addressed to improve process flexibility upon changes in the environment. Ad-hoc process instance changes can be(More)
Reactive behavior is rapidly becoming a key feature of modern software systems in such diverse areas as ubiquitous computing, auto-nomic systems, and event-based supply chain management. In this paper we analyze the convergence of techniques from aspect oriented programming , active databases and asynchronous notification systems to form reactive(More)
Active functionality is especially useful for enforcing business rules in applications, such as Enterprise Application Integration (EAI) and e-commerce. It can be used as glue among existing applications, and for data transformations between heterogeneous applications. However, traditional active mechanisms have been designed for centralized systems and are(More)