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ON RUN-TIME BEHAVIOURAL ADAPTATION IN CONTEXT-AWARE SYSTEMS. Javier Cámara, Gwen Salaün, Carlos Canal GISUM – Deptartamento de Lenguajes y Ciencias de la Computación Universidad de Málaga M-ADAPT'07 1st ECOOP Workshop on Model-Driven Software Adaptation Berlin, Germany, 30th of July 2007.
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ON RUN-TIME BEHAVIOURAL ADAPTATION IN CONTEXT-AWARE SYSTEMS Javier Cámara, Gwen Salaün, Carlos Canal GISUM – Deptartamento de Lenguajes y Ciencias de la Computación Universidad de Málaga M-ADAPT'071st ECOOP Workshop on Model-Driven Software Adaptation Berlin, Germany, 30th of July 2007
Index • Introduction • Case Study: Wireless Medical Information System • Issues in Context-aware, Run-time Adaptation • Proposal • Conclusion and Open Issues
Introduction - COTS • COTS products offer specific functionality needed by larger systems into which they are incorporated. • Promote reusability. • Reduction of development costs and time. But: • COTS products cannot be directly reused (interoperability problems or mismatch among components). • Require customized adaptation.
Introduction - Interoperability Levels • Signature Level: Interface descriptions including methods or services that an entity either offers or requires. • Protocol or Behavioural Level: describes the interactive behaviour that a component follows. • Service Level: groups other sources of mismatch related with non-functional properties (temporal requirements, security, etc.) • Semantic Level: This level describes what the component actually does.
Introduction - Software Adaptation Software Adaptation is characterized by: • Highly dynamic run-time procedures. • Modification or extension of application behaviour. • Extensive use of software adaptors ( special software components with the purpose of solving interoperability problems between other software components). • Adaptors are built from a description of how mismatch between components can be worked out (mapping).
Issues • Context-Aware computing studies the development of systems which exploit context information (e.g., user location, network resources, time, etc.). • The execution context of the system is likely to change at run-time. • Adaptation policies in most proposals in software adaptation are fixed.
Issues • Need of Run-time modifiable adaptation policies dependent on the current state of the context of the system. • Context is complex: depends on many (potentially interrelated) variables Complexity in mapping specification. • Interoperability Issues: • Name mismatch. • 1-to-many interaction • … • Context-triggered actions. • Reconfiguration of the system.
Proposal Composition Engine. Acts as an “Interpreter” deciding which messages to issue depending on context state and mapping information.
Proposal – Mapping – Vector Selection ACTIVE VECTORS vlid vlin vlo vebl vqry vresp vconn vptr vltr vup GLOBAL vlid vresp vlin vlo vptr vqry vltr vup
Conclusions and Open Issues • Approach to the composition of mismatching components in systems where behaviour may be affected by context. • Run-time composition and Separation of Concerns enable and simplify context-aware adaptation. • Implementation using Dynamic AOP (Prose?). • Reconfiguration.