In ubiquitous computing, as more and more devices are introduced into the environment, new applications are made possible that exploit device capabilities in new ways. Currently, however, there is a mismatch between the effort involved in implementing these applications and the benefit they provide. Furthermore, there is a risk that the user loses the understanding of the system and although this is usually not a problem during normal use, it can be problematic if a breakdown occurs. A proposed solution that handles these problems is to use a service oriented architecture and implement applications as composite services and let information about the structure of the composites be available to the user at runtime. As long as the set of services that constitute the composite is static, traditional techniques can be used to specify the composite. But if the member set is dynamic it is problematic to specify which nodes partake in the composite and how they interact. In this paper we introduce mechanisms for handling membership dynamicity in service composition specifications. We demonstrate how an application scenario developed in cooperation with users can be implemented using the mechanisms and sketch how a decentralised interpretation can be realised.
Proceedings of the 5th Minema Workshop: Middleware for Network Eccentric and Mobile Applications, 2007, p. 62-67
Middleware; Palpable Computing; Pervasive Computing; Service Composition; Service Oriented Architecture