WComp middleware for ubiquitous computing: Aspects and composite event-based Web services

Abstract

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

Adaptation Mechanism based on Service-Context Distance for Ubiquitous Computing

“…The adaptation consists in inserting a translation component, at runtime. We have used a mechanism based on ISL (Interaction Specification Language) that is used also in WComp middleware [6].…”

“…In the last years, numerous researchers have concentrated on developing middleware that enables dynamic adaptation. For instance, the WComp middleware [5,6] offers a support for composing and adapting services at runtime. The design and the execution phases are simultaneous.…”

Context-sensitive authorization for asynchronous communications

“…They offer lots of features discussed in [13] such as encapsulation, dynamicity, discoverability and interoperability. They evolved from standard SOA to SOA for device (SOAD) by adding two main features: decentralized reactive discovery and asynchronous communications.…”

“…Since compositions are based on lightweight components, service compositions are fully dynamic. A paradigm called Aspect of Assembly [13] allows to adapt composite services according to specified rules. Aspects of assembly are pieces of information describing how an assembly of components will be structurally modified.…”

“…Moreover, aspects of assembly provide associativity, commutativity and idempotence properties when several aspects are enabled to be weaved at the same time [13].…”