Doctoral Dissertation Proposal

Traditional debugging is a procedural process in that a programmer must proceed step-by- step and object-by-object in order to uncover the cause of an error. In contrast, we explore a declarative approach to debugging in which the execution states of a program are queried through a novel temporal query language. In this proposal, we describe such a language by means of examples and show its potential for declarative debugging of object-oriented programs. The queries may examine individual execution states as well as the history of execution. In this research, we also explore techniques for visualizing the runtime states and execution history of object-oriented programs. The current state of execution is depicted through an enhanced UML object diagram in which both object structure and method activation are represented. The history of execution is depicted by a sequence diagram which claries object interactions. A major contribution of our work lies in showing that declarative queries and runtime visu- alizations complement each other: the queries help reduce the amount of information to be visualized, while the visualizations provide a framework for reporting the answers to queries as well as for formulating the queries themselves. Another important contribution of our research is in devising ecient techniques for reverse stepping and jumping over previous execution states. We are developing an experimental framework for incorporating these ideas as an ex- tension of the Eclipse Integrated Development Environment (IDE) for Java. This dissertation proposal describes our results to date and also outlines our proposed research in the areas of scalable visualizations, interactive execution, and declarative query languages.