Extracting ontologies from legacy systems for understanding and re-engineering

Ontology has been investigated in the context of knowledge sharing among heterogeneous and disparate database and knowledge base systems. Our recent study and experiments suggest that ontology also have a great potential for legacy software understanding and re-engineering. In this paper we consider an ontology to be composed of four elements: classes, relations, functions and instances. We show these four elements forming an ontology for a legacy system can be extracted from the code of the concerned system using the existing software re-engineering tools. We then present our vision how the obtained ontology can be applied to understanding and eventually better re-engineering the legacy systems.