Software evolution visualization Citation for published version (APA): Voinea, S. L. (2007). Software evolution visualization. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR629335 DOI: 10.6100/IR629335 Document status and date: Published: 01/01/2007 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. 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Lukkien CIP-DATA LIBRARY TECHNISCHE UNIVERSITEIT EINDHOVEN Voinea, Stefan-Lucian Software Evolution Visualization / door Stefan-Lucian Voinea. - Eindhoven : Technische Universiteit Eindhoven, 2007. Proefschrift. - ISBN 978-90-386-1099-3 NUR 992 Subject headings: computer visualisation / software maintenance / image communication CR Subject Classification (1998) : I.3.8, D.2.7, H.3.3 Promotor: prof. dr. ir. J.J. van Wijk (Technische Universiteit Eindhoven) Copromotoren: dr. ir. A.C. Telea (Technische Universiteit Eindhoven) dr. J.J. Lukkien (Technische Universiteit Eindhoven) Kerncommissie: prof. dr. S. Diehl (Universit¨at Trier) prof. dr. A. van Deursen (Delft University of Technology) prof. dr. M.G.J. van den Brand (Technische Universiteit Eindhoven) Advanced School for Computing and Imaging The work in this thesis has been carried out in the research school ASCI (Advanced School for Computing and Imaging). ASCI dissertation series number: 149 c S.L. Voinea 2007. All rights are reserved. Reproduction in whole or in part is allowed only with the written consent of the copyright owner. Printing: Eindhoven University Press Cover design: S.L. Voinea Front cover image: “Binary code” c Andrey Prokhorov Back cover image: “Cyber business” c Emrah T¨ur¨ud¨u Contents 1 Introduction 1 1.1 TheSoftwareChallenge .......................... 1 1.2 SoftwareVisualization . 2 1.3 SoftwareEvolutionVisualization . .... 5 1.4 Outline ................................... 7 2 Background 9 2.1 Introduction................................. 9 2.2 DataExtraction ............................... 12 2.3 ReverseEngineering ............................ 13 2.4 EvolutionAnalysis ............................. 15 2.4.1 Requirements............................ 16 2.4.2 EvolutionDataAnalysisTools . 16 2.4.3 EvolutionVisualizationTools . 18 2.5 Conclusions................................. 23 3 Software Evolution Domain Analysis 27 3.1 Introduction................................. 27 3.2 SystemEvolution .............................. 28 3.3 SoftwareEvolution ............................. 33 3.4 SoftwareRepositories. 36 3.4.1 CVS................................. 36 3.4.2 Subversion ............................. 40 3.5 Conclusions................................. 40 v vi 4 A Visualization Model for Software Evolution 43 4.1 Introduction................................. 43 4.2 SoftwareVisualizationPipeline. .... 45 4.3 DataAcquisition .............................. 46 4.4 DataFilteringandEnhancement . 47 4.4.1 Selection .............................. 48 4.4.2 Metrics ............................... 49 4.4.3 Clustering.............................. 50 4.5 DataLayout................................. 51 4.6 DataMapping................................ 52 4.7 Rendering.................................. 53 4.8 UserInteraction............................... 54 4.9 Conclusions................................. 55 5 Visualizing Software Evolution at Line Level 57 5.1 Introduction................................. 57 5.2 DataModel ................................. 58 5.3 VisualizationModel............................. 62 5.3.1 LayoutandMapping . 62 5.3.2 MultipleViews ........................... 67 5.3.3 VisualImprovements. 69 5.3.4 UserInteraction.. .... .... .... .... ... .... .. 70 5.4 Use-CasesandValidation. 73 5.5 Conclusions................................. 76 6 Visualizing Software Evolution at File Level 79 6.1 Introduction................................. 79 6.2 DataModel ................................. 80 6.3 VisualizationModel............................. 80 6.3.1 LayoutandMapping . 81 6.3.2 MetricViews ............................ 86 6.3.3 MultivariateVisualization . 87 6.3.4 MultiscaleVisualization . 92 vii 6.3.5 UserInteraction.. .... .... ... .... .... .... .. 97 6.4 Use-CasesandValidation. 98 6.4.1 InsightwithDynamicLayouts . 98 6.4.2 ComplexQueries. 100 6.4.3 SystemDecomposition. 101 6.5 Conclusions................................. 103 7 Visualizing Software Evolution at System Level 105 7.1 Introduction................................. 105 7.2 DataModel .................................106 7.2.1 DataSampling ........................... 107 7.3 VisualizationModel.... .... .... ... .... .... .... .. 109 7.3.1 LayoutandMapping . 109 7.3.2 VisualScalability. 111 7.3.3 UserInteraction. 115 7.4 Use-CasesandValidation. 117 7.5 Conclusions................................. 122 8 Visualizing Data Exchange in Peer-to-Peer Networks 125 8.1 Introduction................................. 125 8.2 ProblemDescription ... .... .... ... .... .... .... .. 126 8.3 DataModel .................................128 8.4 VisualizationModel.... .... .... ... .... .... .... .. 130 8.4.1 ServerVisualization . 131 8.4.2 DownloadVisualization . 136 8.4.3 CorrelationVisualization. 137 8.5 Use-CasesandValidation. 139 8.6 Conclusions................................. 141 9 Lessons Learned 143 9.1 DataAcquisitionandPreprocessing . 143 9.2 SoftwareEvolutionVisualization . 144 9.3 Evaluation.................................. 147 viii 10 Conclusions 149 10.1 OnDataPreprocessing . 149 10.2 OnSoftwareEvolutionVisualization . ... .. 150 10.3 OnEvaluation................................ 150 10.4FutureWork................................. 151 Bibliography 155 List of Publications 165 Summary 169 Acknowledgements 171 Chapter 1 Introduction In this chapter we identify complexity and change as two major issues of the software industry and we introduce software evolution visualization as a promising approach for addressing them. We present the target audience of this type of visualization, the questions it tries to answer and the challenges it poses. Finding ways to design effective and efficient visualizations of software evolution is our goal and the focus of this thesis. 1.1 The Software Challenge Software has today a large penetration in all aspects of society. According to Bjarne Stroustrup, the creator of the highly popular programming language C++, “Our civilization runs on software” (Bjarne Stroustrup, 2003). This penetration took place rapidly in the last two decades and continues to increase at a steady pace. However, the software industry is confronted with two increasingly serious problems. The first problem of the software industry concerns the complexity of software. While a mid-size software application twenty years ago had a few thousands or tens of thou- sands of lines of code, mid-size applications nowadays have tens of millions of lines of code. Even relatively simple applications, such as the familiar Microsoft Windows Paint program, consist of tens of thousands of lines of code, spread over hundreds of files, de- veloped by tens of people over many years. These figures are orders of magnitude larger for banking, telecom, or industrial applications. Software code can be structured in many ways, e.g., as a file hierarchy; as a network of components, functions, or packages; or as a set of design patterns [49] or aspects [38, 57]. No single hierarchy suffices for under- standing software, and the inter-hierarchy