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Motivation

The goal of the PCM is to provide modeling capabilities that enable QoS analyses of component-based software architectures. As clients perceive different QoS characteristics of a provided service in a component-based architecture depending on a particular context, component developers have to provide parameterised specifications of the QoS attributes of their components. Such context dependencies for a specific component service may originate from a) input parameters (including the current component internal state), b) resource usage, and c) usage of required services. These influences have to be made explicit in the service's specification.

To achieve accurate QoS analyses, a description of the usage of required services (influence c)) for each provided service of a component is useful, because the QoS characteristics perceived at the provided interface can depend on QoS characteristics of calls to required services. For example, consider a provided service calling a slow required service. In this case, the response time of the provided service will be perceived as slow by its clients, because the execution time of the slow required service has to be included in its own execution time (details can be found in [27]). software architects cannot know how requests to a provided service of a component are propagated to required services if no dependencies between them are specified. Thus, component developers have to enhance their component specifications with a description of such intra-component dependencies to enable accurate specification-based QoS analyses by third parties.


next up previous contents index
Next: Description Up: Service Effect Specification Previous: Service Effect Specification   Contents   Index
Snowball 2007-03-16