A Flexible Model and Implementation of Component Controllers

The GCM (Grid Component Model) is a component model that is being defined by the CoreGRID institute on Programming Models; it is based on the Fractal component model. It is intended at overcoming the insufficiencies of the existing component systems when it comes to Grid computing. Its main characteristics are: hierarchical composition, structured communications with support for asynchrony, support for deployment, functional and non-functional (NF) adaptivity, and autonomicity. As in the Fractal component model, the GCM distinguishes controllers which implement NF concerns and are gathered in a membrane from the functional content of the component. This article presents a refinement of the Fractal/GCM model and an API for adopting a component design of the component membranes, as suggested by the GCM specification. The objective of this framework is to provide support for both adaptivity and autonomicity of the component control part. In the design of the model refinement and the API for NF components, we also take into account hierarchical composition and distribution of the membrane, which is crucial in the GCM. Our approach is flexible because it allows “classical” controllers implemented by usual objects to coexist with highly dynamic and reconfigurable controllers implemented as components.