and thus must adapt to external conditions; all layers must make cost-based decisions about what mode of operation to use in response to performance feedback. This paper focuses on the generic interface between adjacent layers (client and server) in a multi-level hierarchy. The Adaptive Research Contracts (ARC) framework uses a bottom-up approach in which the server exposes a range of quality/cost modes to the client above. This allows the client to trade off various algorithms generating different workloads for multiple resources. A case study shows that control can be distributed effectively over multiple layers with ARC; global cost-effective solutions can be obtained with exchanging a small fraction of all possible control settings.

We propose an adaptive middleware design for context-aware applications that abstracts the applications from the sensors that provide context. Further, we use application-specific utility functions to choose, given multiple alternatives for providing a specific context, one alternative at any time that provides the context for all applications, whilst maximising the applications' total "satisfaction " with the quality of context from the chosen provider. Our middleware also implements autonomic properties, such as selfconfiguration and resilience to failures, in the provision of context information to context-aware applications.

Autonomic Computing is a concept that brings together many fields of computing with the purpose of creating computing systems that self-manage. In its early days it was criticised as being a “hype topic” or a rebadging of some Multi Agent Systems work. In this survey, we hope to show that this was not indeed ’hype ’ and that, though it draws on much work already carried out by the Computer Science and Control communities, its innovation is strong and lies in its robust application to the specific self-management of computing systems. To this end, we first provide an introduction to the motivation and concepts of autonomic computing and describe some research that has been seen as seminal in influencing a large proportion of early work. Taking the components of an established reference model in turn, we discuss the works that have provided significant contributions to that area. We then look at larger scaled systems that compose autonomic systems illustrating the hierarchical nature of their architectures. Autonomicity is not a well defined subject and as such different systems adhere to different degrees of Autonomicity, therefore we cross-slice the body of work in terms of these degrees. From this we list the key applications of autonomic computing and discuss the research work that is missing and what we believe the community should be considering.

The mobile radio systems beyond third generation (3G) will evolve in all-IP systems, integrating Internet and mobile systems advantages. BRAIN project is developing a system architecture which combines local coverage broadband radio access systems based in HIPERLAN/2 with several wider coverage mobile radio systems, enabling full coverage of seamless IP-based services for users in hot spot areas and on the move. End to end quality of service (QoS) provision is one of the mayor challenges in the design of such a system and must be supported by the application, network and wireless access layers. This paper proposes a QoS system architecture, including the terminal architecture, the IP based access network and the main characteristics of the enhancements to the air interface based in HIPERLAN/2 focusing on its wireless QoS support. 1.

Weiser’s vision of ubiquitous computing [14] involves the notion of calm whereby the system, which may be composed of many very differing forms of computing elements, tailors its operation to best fit the user, application Copyright © 200x Inderscience Enterprises Ltd.

Next generation network architectures will benefit from the many years of practical experience that have been gained in designing, using and operating network protocols. Over time, the networking community has gradually improved its understanding of networked systems in terms of architecture, design, engineering and testing. However, as protocols and networked systems become more complex, it is our contention that it will be necessary for programming techniques to evolve similarly so that they better support the design, implementation and testing of both the functional and the non-functional requirements for the network protocols that will be used. We therefore envisage new levels of programming language support that permit: (a) the design and implementation of new protocols with provably correct construction; (b) inline testing; and (c) the expression of protocol behaviour within the design. Based on our ongoing work with both network protocols and programming language design, we believe that exploiting the capabilities of recent work in Domain Specific Languages (DSLs) will allow us to meet such requirements, allowing straightforward and “correctby-construction” design and implementation of next generation network protocols. 1.

this paper withnhA5wP routin strategies that areconPP ainP by requiremenA of preservation or adequate tradin of QoS values, as proposed, e.g.,in [16] [17].

Results of the conceptual work carried out during the BRAIN project concerning the BRAIN QoS Framework and the Brain ENd Terminal Architecture (BRENTA) is presented. This includes mechanisms to specify and manage QoS End-to-End including mobile end-systems and IP based wireless access networks in the transmission path. One of the key points is to manage QoS end-to-end from the users and media point of view and provide well-defined adaptation strategies in the case that QoS at the network level cannot be guaranteed for the whole session. This is likely to occur in mobile environments, because of potential handovers (horizontal and vertical) and error rate patterns of wireless links in contrast to fixed networks. The design of selected parts of BRENTA is currently under study within the MIND (www.ist-mind.org) project with respect to ad hoc network aspects, and security.

The paper discusses the design and prototype implementation of a QoS aware multimedia repository. We present an overview of the issues encountered as well as a proposed design solution.

Next generation network architectures will benefit from the many years of practical experience that have been gained in designing, using and operating network protocols. Over time, the networking community has gradually improved its understanding of networked systems in terms of architecture, design, engineering and testing. However, as protocols and networked systems become more complex, it is our contention that it will be necessary for programming techniques to evolve similarly so that they better support the design, implementation and testing of both the functional and the non-functional requirements for the network protocols that will be used. We therefore envisage new levels of programming language support that permit: (a) the design and implementation of new protocols with provably correct construction; (b) inline testing; and (c) the expression of protocol behaviour within the design. Based on our ongoing work with both network protocols and programming language design, we believe that exploiting the capabilities of recent work in Domain Specific Languages (DSLs) will allow us to meet such requirements, allowing straightforward and “correctby-construction” design and implementation of next generation network protocols. 1.