Trader-Based Component Frameworks

Component-based software development makes specific demands on infrastructures and on the techniques used for framework construction and customization. We have developed a component framework (Combo) for editors with direct manipulation interfaces. The framework was developed using an object-oriented environment and can be customized by plugging in binary software components at run-time. We use a flexible trading mechanism for selecting appropriate components for specific tasks from component sets, which relies on meta-information about a component's incoming and outgoing interfaces, and (non-functional) properties. Contrary to many object systems where this information is extracted from type information provided by the run-time environment or by type repositories, it has to be supplied by the components themselves in our system. The framework was developed to serve as the basis for an open tool environment that supports browsing and editing of object-oriented, framework-based software architectures. Originally implemented in C++/ET++, parts of the framework have been re-implemented in Java.