After a survey of the specific features of ubiquitous computing applications and corresponding middleware requirements, we list the various paradigms used in the main middlewares for ubiquitous computing in the literature. We underline the lack of works introducing the use of the concept of Aspects in middleware dedicated to ubiquitous computing, in spite of them being used for middleware improvement in other domains. adaptation approach using the original concept called Aspect of Assembly. These paradigms lead to two ways to dynamically design ubiquitous computing applications. The first implements a classical component-based compositional approach to design higher-level composite Web Services and then allow to increment the graph of cooperating services for the applications. This approach is well suited to design the applications in a known, common, and usual context. The second way uses a compositional approach for adaptation using Aspect of Assembly, particularly well-suited to tune a set of composite services in reaction to a particular variation of the context or changing preferences of the users. Having detailed Aspect of Assembly concept, we finally comment on results indicating the expressiveness and the performance of such an approach, showing empirically that principles of aspects and program integration can be used to facilitate the design of adaptive applications.Keywords Ubiquitous computing · Web services for devices · Event-based component middleware · Software composition Ubiquitous computingWe are standing on the brink of a new computing era, one that will fundamentally transform our computing usages. In September 1991, Mark Weiser in [38] unveiled his vision of ubiquitous computing. He described the future like a world where computing systems are available anywhere but not visible. Already, early forms of ubiquitous computing are obvious in the

Pervasive devices are becoming popular and smaller. Those mobile systems should be able to adapt to changing requirements and execution environments. But it requires the ability to reconfigure deployed codes, which is considerably simplified if applications are component-oriented rather than monolithic blocks of codes. So, we propose a middleware called WComp which federates an event-driven componentoriented approach to compose distributed services for devices. This approach is coupled with adaptation mechanisms dealing with separation of concerns. In such mechanisms, aspects (called Aspects of Assembly) are selected either by the user or by a self-adaptive process and composed by a weaver with logical merging of high-level specifications. The result of the weaver is then projected in terms of pure elementary modifications of components assemblies with respect to blackbox properties of COTS components. Our approach is validated by analyzing the results of different experiments drawn from sets of application configurations randomly generated and by showing its advantages while evaluating the additional costs on the reaction time to context changing.

Due to more and more mobile computers moving among smart and communicating devices in our everyday life, we observe the emergence of new constraints in software design. Indeed, device heterogeneity, dynamic software variation, and frequent mobile device apparition/disappearance make software applications compulsorily adapt to their context. In this paper, we will present an enhancement of ambient computing discovery mechanisms adding context handling capabilities to Web Services for Devices. As a matter of fact, we define contextual parameters for broadcast requests so that only devices in the "selected context" reply, which aim at reducing the overall number of exchanged messages on the network.