Runtime Concepts of Hierarchical Software Components

Components have become a widely accepted concept used in building large-scale applications. Although the concept of a component is not really new, it is generally not clear how to deal with the component abstraction at runtime. This manifests in the fact that nowadays component systems can be basically divided (a) to those being rich in advanced features (e.g., hierarchical components, software connectors, versioning, dynamic architectures), but which have typically only poor or even no runtime support, and (b) to those with a solid runtime support, but which typically possess only a limited set of the advanced features. In our opinion, this is mainly due to the difficulties that arise when trying to give proper semantics to the features and reify them in development tools and an runtime platform. In this paper, we describe the implementation of the runtime environment for the SOFA 2.0 component model. In particular, we focus on the runtime support of the advanced features mentioned above. The described issues and corresponding solutions are not specific only to SOFA 2.0, but they are generic enough to be applicable to any other component system aiming at addressing those advanced features.