PCOMs: A Component Model for Building Context-Dependent Applications

In this paper, we present a model to dynamically compose adaptable context-dependent applications using context conditions. The contributions of this work are: designing components as compositions of behaviour; embedding decision points in the component at development time to determine component behaviour; supporting reconfiguration of decision policies at runtime to adapt behaviours. The approach is a component-based one that modifies the application architecture by subdividing components into subsystems of static and dynamic elements. We map each context condition to a composable template architectural configuration. Each context condition acts to select behavioural patterns, which combine to form application architectures. Patterns describe system adaptation in term of adjustments of sub-elements of component behaviour. Our approach is dependent on the identification of sub-elements on the component suitable for localising context dependent changes such that alternatives versions tailored to specific context to be woven in the application at runtime as context varies. We illustrate this approach with a simple case study.