Advances in pervasive technology have made it possible to consider large-scale application types that potentially span heterogeneous organisations, technologies and device types. This class of application will have a multi-layer architecture, where each layer is likely to use languages and technologies appropriate to its own concerns. An example application is a geographically-large-scale crisis management system. Typically, such applications are required to dynamically adapt their behaviour based on current circumstances, with adaptations potentially affecting all layers of the application. The complexities involved in dynamically adapting multi-layer applications will significantly benefit from formal approaches to its specification. This paper presents a new methodology for flexible, multi-layer application adaptation, with layer-specific adaptation solution templates bound to application mismatches that are organised into hierarchical taxonomies. Templates can be linked either through direct invocations or through adaptation events, supporting flexible cross-layer adaptation. The methodology illustrates the use of different formalisms for different elements of its specification. In particular, we combine semi-formal metamodelling techniques for the system model specification with formal Petri nets, which are used to capture template matchmaking using reachability analysis. This work demonstrates how existing formalisms can be used for the specification of a generic adaptation model for pervasive applications.
Abstract-Current adaptation approaches mainly work in isolation and cannot be easily integrated to tackle complex adaptation scenarios. The few existing cross-layer adaptation techniques are somewhat inflexible because the adaptation process is predefined and static.In this paper we propose a methodology for the dynamic and flexible adaptation of multi-layer applications. We use events to trigger the process of matching adaptation templates, which expose adaptation logic as BPEL processes. The matching process employs taxonomies of adaptation mismatches to select adaptation templates based on the degree of match between events and adaptation mismatches. We provide support for cross-layer adaptation by allowing templates to be composed either directly, through invocations of WSDL operations or indirectly, through events.
Athanasios Staikopoulos, Trinity College Dublin requirements, does of course not make it easier to use or to control. In particular, business processes demand resilience and real-time adaptation in the face of changing business requirements, incorporation of alternative services, and fi nding suitable substitutes when those needed are unavailable. The European Union-funded Alive project (http:// www.ist-alive.eu) is prototyping ideas, driven by commercial and industrial use cases, that utilize research in organizational modeling, software agents, model-driven engineering, artifi cial intelligence, the Semantic Web, and Web services to construct tools and demonstrators to address these needs. This article outlines the Alive architecture for serviceoriented computing, describes some of the innovative tools we have developed and illustrates it all with a detailed run-through from one of our use cases.
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