Abstract—Understanding source code is an important task in the maintenance of software systems. Legacy systems are not only limited to procedural languages, but are also written in object-oriented languages. In such a context, understanding classes is a key activity as they are the cornerstone of the object-oriented paradigm and the primary abstraction from which applications are built. Such an understanding is however difficult to obtain because of reasons such as the presence of late binding and inheritance. A first level of class understanding consists of the understanding of its overall structure, the control flow among its methods, and the accesses on its attributes. We propose a novel visualization of classes called class blueprint that is based on a semantically enriched visualization of the internal structure of classes. This visualization allows a software engineer to build a first mental model of a class that he validates via opportunistic code-reading. Furthermore, we have identified visual patterns that represent recurrent situations and as such convey additional information to the viewer. The contributions of this article are the class blueprint, a novel visualization of the internal structure of classes, the identification of visual patterns, and the definition of a vocabulary based on these visual patterns. We have performed several case studies of which one is presented in depth, and validated the usefulness of the approach in a controlled experiment. Index Terms—Object-oriented programming, software visualization, reverse engineering, visual patterns, smalltalk. 1

Scenario diagrams are a well-known notation for visualizing the message flow in object-oriented systems. Traditionally, they are used in the analysis and design phases of software development to prototype the expected behavior of a system. We show how they can be used reversely for understanding and browsing existing software. We have implemented a tool called Scene that automatically produces scenario diagrams for existing objectoriented systems. The tool makes extensive use of an active text framework providing the basis for various hypertext-like facilities. It allows the user to browse not only scenarios but also various kinds of associated documents, such as source code (method definitions and calls), class interfaces, class diagrams, and call matrices. 1 Introduction The static structure of object-oriented software is usually easy to understand because of the close correspondence between the software units (classes) and the concepts of the application domain. However, the dynami...

. UML is currently embraced as "the" standard in object-oriented modeling languages, the recent work of OMG on the Meta Object Facility (MOF) being the most noteworthy example. We welcome these standardisation efforts, yet warn against the tendency to use UML as the panacea for all exchange standards. In particular, we argue that UML is not sufficient to serve as a tool-interoperability standard for integrating round-trip engineering tools, because one is forced to rely on UML's built-in extension mechanisms to adequately model the reality in source-code. Consequently, we propose an alternative meta-model (named FAMIX), which serves as the tool interoperability standard within the FAMOOS project and which includes a number of constructive suggestions that we hope will influence future releases of the UML and MOF standards. Keywords: meta model, unified modeling language (UML), meta-object facility (MOF), interoperability standard, famoos information exchange (FAMIX) 1 Intr...

Tracking the changing dynamics of object-oriented frameworks[5], design patterns[7], architectural styles[8], and subsystems during the development and reuse cycle can aid producing complex systems. Unfortunately, current object-oriented programming tools are relatively oblivious to the rich architectural abstractions in a system. This paper shows that architecture-oriented visualization, the graphical presentation of system statics and dynamics in terms of its architectural abstractions, is highly beneficial in designing complex systems. In addition, the paper presents architecture-aware instrumentation, a new technique for building efficient on-line instrumentation to support architectural queries. We demonstrate the effectiveness and performance of the scheme with case studies in the design of the Choices object-oriented operating system. 1 Introduction Designers conceive complex systems as architectures with design patterns[7], frameworks[5], architectural styles[8], and subsyste...

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...

This paper describes the dotplot data visualization technique and its potential for contributingto the identification of design patterns. Pattern languages have been used in architectural design and urban planning to codify related rules-of-thumb for constructing vernacular buildings and towns. When applied to software design, pattern languages promote reuse while allowing novice designers to learn from the insights of experts. Dotplots have been used in biology to study similarity in genetic sequences. When applied to software, dotplots identify patterns that range in abstraction from the syntax of programming languages to the organizational uniformity of large, multi-component systems. Dotplots are useful for design by successive abstraction---replacing duplicated code with macros, subroutines, or classes. Dotplots reveal a pervasive design pattern for simplifying algorithms by increasing the complexity of initializations. Dotplots also reveal patterns of wordiness in languages---one...

Understanding the run-time behavior of object-oriented legacy systems is a complex task due to factors such as late binding and polymorphism. Current approaches extract and use information from the complete execution trace of a system. The sheer size and complexity of such traces make their handling, storage, and analysis difficult. Current software systems which run almost non-stop do not permit such a full analysis. In this paper we present a lightweight approach based on the extraction of a condensed amount of information, e.g., measurements, that does not require a full trace. Using this condensed information, we propose a visualization approach which allows us to identify and understand certain aspects of the objects' lifetime such as their role played in the creation of other objects and the communication architecture they support.

The reverse engineering of large scale object-oriented legacy systems is a challenging task with a definite need for approaches helping to have a fast overview and to focus on the problematic parts. This paper investigates a hybrid approach, combining the immediate appeal of visualizations with the scalability of metrics. We validate our approach by showing how CodeCrawler, the experimental platform we built allowed us to reengineer some applications. Keywords: Reverse Engineering, Program Visualization, Software Metrics, CodeCrawler 1 Introduction "While the benefits of object-oriented technology are widely recognized, the indiscriminate use of object-oriented mechanisms and weaknesses in analysis and design methods are rapidly leading to a new generation of inflexible legacy systems." [4]. The ability to reverse engineer object-oriented legacy systems has become a vital matter in today's software industry. Early adopters of the object-oriented programming paradigm are now fa...

Program comprehension is an important activity in software maintenance, as software must be sufficiently understood before it can be properly modified. The study of a program’s execution, known as dynamic analysis, has become a common technique in this respect and has received substantial attention from the research community, particularly over the last decade. These efforts have resulted in

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