Software development and maintenance tasks rely on and can benefit from an increased level of program understanding. Object-oriented programming languages provide features which facilitate software maintenance, yet the same features often make object-oriented programs more difficult to understand. We support the use of program visualization techniques to foster object-oriented program comprehension. This paper identifies ways that visualization can increase program understanding, and presents a means for characterizing both static and dynamic aspects of an object-oriented program. We then describe the implementation of a prototypical tool for visualizing the execution of C++ programs. Based on this work, we define a framework for the visualization of object-oriented software which requires little or no programmer intervention and provides a mechanism which allows users to focus quickly on particular aspects of the program. Keywords: program visualization, program comprehension. 1 In...

Abstract. Program errors are hard to find because of the cause-effect gap between the time when an error occurs and the time when the error becomes apparent to the programmer. Although debugging techniques such as conditional and data breakpoints help to find error causes in simple cases, they fail to effectively bridge the cause-effect gap in many situations. Dynamic query-based debuggers offer programmers an effective tool that provides instant error alert by continuously checking inter-object relationships while the debugged program is running. To speed up dynamic query evaluation, our debugger (implemented in portable Java) uses a combination of program instrumentation, load-time code generation, query optimization, and incremental reevaluation. Experiments and a query cost model show that selection queries are efficient in most cases, while more costly join queries are practical when query evaluations are infrequent or query domains are small. 1.

Source code analysis and inspection does not provide enough information to describe the structure of an objectoriented program completely because there are components and relations that only exist during its runtime. This paper presents a tool, called Gadget, that helps software engineers extract the dynamic structure of objectoriented programs written in the Java programming language. The tool uses program profiling, filtering, and graph clustering techniques. In this work we show how Gadget is used to analyze a standard graphical user interface library for Java, called Swing. This library has a complex structure, part of which we expose using data gathered by Gadget during the execution of a simple Java program that uses Swing. 1.

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Previous work in software visualization has demonstrated the advantages of presenting programs in a graphical manner in both program understanding and debugging. Among the class of program visualization systems are those which operate non-intrusively on program sources. One of the major challenges faced by users of such systems is the problem of filtering the enormous amount of run-time information present during the execution of a large system. In this thesis, I describe an evolution of the Software Landscape. The Software Landscape is a tool for browsing a software system's static structure using boxes together with arrow and containment relations. My Run-Time Landscape includes run-time information, utilizes the Landscape paradigm for the elision of unwanted details, and provides a tightly integrated environment for viewing program artifacts from different perspectives. This prototype is useful in debugging, program understanding, and profiling. ii Acknowledgements I am grateful...

Erklärung gemäß §23 der Diplom-Prüfungsordnung: Hiermit erkläre ich, daß ich die Arbeit selbständig durchgeführt und keine anderen als die angegebenen Quellen und Hilfsmittel verwendet habe. ii 04.02.98 15:27

Modelling the dynamic aspects of an object-oriented design is important to gain concrete insight into the ways objects interact and relate to each other. A similar insight may be obtained from a static model, but at a more abstract level and in a more indirect way. Dynamic models are usually presented as graph-based diagrams in which the vertices are objects and the edges are messages or relations among objects. In this paper we study such diagrams as the basis for tools in a dynamic modelling environment. We are especially interested in different ways to present time in such tools. One particular approach is to present "time by time", hereby leading to animation of dynamic models. By introducing the idea of `design by animation' we aim at a radical improvement of the presentation and manipulation of dynamic models in contemporary CASE tools. 1 Introduction Diagrammatic, graph-based presentations play an important role as the documentation of an object-oriented model. This...