Reuse, CORBA, and knowledge-based systems

By applying recent advances in the standards for distributed computing, we have developed an architecture for a CORBA implementation of a library of platform-independent, sharable problem-solving methods and knowledge bases. The aim of this library is to allow developers to reuse these components across different tasks and domains. Reuse should be cost effective; therefore, the library will include standard problem-solving methods whose semantics are well understood and are described with a language for stating the requirements and capabilities of a component. In addition, when a developer needs to adapt a component to a new task, the adaptation costs should be minimal. Thus, we advocate the use of separate mediating components that isolate these adaptations from the original component. We demonstrate our approach with an example: an implementation of a problem-solving method, a knowledge-base server, and mediating components that adapt the method to different knowledge bases and tasks. 1. Cost-Effective Reuse Researchers in both knowledge-based systems and in software engineering have looked to reuse as a methodology for reducing the high cost of software development and maintenance. With a reuse approach to software construction, developers adapt existing software components at a fraction of the cost of developing a system from scratch. Reuse can save development costs when (1) the overhead cost of building a component for reuse is low, (2) the frequency with which developers reuse components is high, and (3) the cost of finding, and adapting a component is low. Unfortunately, there are a number of obstacles to overcome before component reuse is cost effective. Reuse is not cost-effective when the cost of building, finding and adapting a library component is greater than the cost of building a solution from scratch. Reuse is cost effective only when the developer can find and understand a component quickly, and when the component solves a significant problem: one that would be expensive to solve with software built and debugged from scratch.