The scope of software visualization tools which exist for the navigation, analysis and presentation of software information varies widely. One class of tools, which we refer to as software exploration tools, provide graphical representations of software structures linked to textual views of the program source code and documentation. This paper describes a hierarchy of cognitive issues which should be considered during the design of a software exploration tool. The hierarchy of cognitive design elements is derived through the examination of program comprehension cognitive models. Examples of how existing tools address each of these issues are provided.

Treemaps, a space-filling method of visualizing large hierarchical data sets, are receiving increasing attention. Several algorithms have been proposed to create more useful displays by controlling the aspect ratios of the rectangles that make up a treemap. While these algorithms do improve visibility of small items in a single layout, they introduce instability over time in the display of dynamically changing data, fail to preserve order of the underlying data, and create layouts that are difficult to visually search. In addition, continuous treemap algorithms are not suitable for displaying quantum-sized objects within them, such as images. This paper introduces several new treemap algorithms, which address these shortcomings. In addition, we show a new application of these treemaps, using them to present groups of images. The ordered treemap algorithms ensure that items near each other in the given order will be near each other in the treemap layout. Using experimental evidence from Monte Carlo trials, we show that compared to other layout algorithms ordered treemaps are more stable while maintaining relatively favorable aspect ratios of the constituent rectangles. A second test set uses stock market data. The quantum treemap algorithms modify the layout of the continuous treemap algorithms to generate rectangles that are integral multiples of an input object size. The quantum treemap algorithm has been applied to PhotoMesa, an application that supports browsing of large numbers of images. Keywords:

Algorithm visualization (AV) technology graphically illustrates how algorithms work. Despite the intuitive appeal of the technology, it has failed to catch on in mainstream computer science education. Some have attributed this failure to the mixed results of experimental studies designed to substantiate AV technology's educational effectiveness. However, while several integrative reviews of AV technology have appeared, none has focused specifically on the software's effectiveness by analyzing this body of experimental studies as a whole. In order to better understand the effectiveness of AV technology, we present a systematic metastudy of 24 experimental studies. We pursue two separate analyses: an analysis of independent variables, in which we tie each study to a particular guiding learning theory in an attempt to determine which guiding theory has had the most predictive success; and an analysis of dependent variables, which enables us to determine which measurement techniques have been most sensitive to the learning benefits of AV technology. Our most significant finding is that how students use AV technology has a greater impact on effectiveness than what AV technology shows them. Based on our findings, we formulate an agenda for future research into AV effectiveness.

Software developers spend significant time gaining and maintaining awareness of fellow developers ’ activities. FASTDash is a new interactive visualization that seeks to improve team activity awareness using a spatial representation of the shared code base that highlights team members ’ current activities. With FASTDash, a developer can quickly determine which team members have source files checked out, which files are being viewed, and what methods and classes are currently being changed. The visualization can be annotated, allowing programmers to supplement activity information with additional status details. It provides immediate awareness of potential conflict situations, such as two programmers editing the same source file. FASTDash was developed through usercentered design, including surveys, team interviews, and in situ observation. Results from a field study show that FASTDash improved team awareness, reduced reliance on shared artifacts, and increased project-related communication. Additionally, the team that participated in our field study continues to use FASTDash.

Therapy planning plays an increasingly important role in the everyday work of physicians. Clinical protocols

Software products are often released with missing functionality, errors, or incompatibilities that may result in failures in the field, inferior performances, or, more generally, user dissatisfaction. In previous work, we presented the Gamma technology, which facilitates remote analysis and measurement of deployed software and allows for gathering programexecution data from the field. When monitoring a high number of deployed instances of a software product, however, a large amount of data is collected. Such raw data are useless in the absence of a suitable data-mining and visualization technique that supports exploration and understanding of the data. In this paper, we present a new technique for collecting, storing, and visualizing program-execution data gathered from deployed instances of a software product. We also present a prototype toolset, Gammatella, that implements the technique. We show how the visualization capabilities of Gammatella allows for effectively investigating several kinds of execution-related information in an interactive fashion.

Software programs, especially legacy programs, are often large, complex and poorly documented. To maintain these programs software engineers require a variety of efficient analytical tools. Some software maintenance tools use visualizations (i.e. graphical views) to communicate information about software systems. Although many software visualization tools exist, the majority of them are not very effective in practice. Part of the problem is that they are designed in an ad hoc manner, with little empirical evaluation. They are often criticized because they try to force programmers to use a specific approach to understanding software rather than supporting their own approaches. The result is that current software visualization tools do not play as big a role in industry as was anticipated by some researchers. The tools that are used are very basic, consisting of mainly text editors and searching features. With increasingly fast computing platforms, there is great potential for the use of...

This thesis introduces a user interface that supports the understanding and manipulation of timeoriented, This user interface is called AsbruView, and is based on the plan representation language Asbru, which is used for medical therapy planning. Clinical protocols are seen in Asbru as timeoriented, AsbruView utilizes Metaphors of running tracks and traffic control to communicate important concepts and uses glyphs to depict the complex time annotations used in Asbru. Two different views show different aspects of the same set of plans: One shows the topology of plans and which parts have been defined, the other captures the temporal dimension and the structure of plans.

Distributed software development suffers from limited collaboration capabilities, as developers are unable to easily coordinate their efforts across physical boundaries. Different fields, such as CSCW and groupware, have attempted to bridge this gap, but few of the approaches developed so far have been incorporated in current software development environments. Configuration Management (CM) systems are vital to any software development process, support distributed development, and are in widespread use. Unfortunately, they have only limited support for distributed collaboration. In this paper we describe Palantír, a system that is aimed at bringing collaborative capabilities to distributed development. Palantír builds upon existing CM systems to introduce project awareness to the developer workspace. In particular, Palantír supports close collaboration among developers by visualizing concurrent changes and showing, in real time, the severity and impact of those changes on the developer’s workspace. 1.

The paper describes a system, Imsovision, for visualizing object-oriented software in a Virtual Reality Environment. A visualization language (COOL) is defined that maps C++ source code to a visual representation. Our aim is to develop a language with few metaphors and constructs, but with the ability to represent a variety of elements with no ambiguity or loss of meaning. In addition, the visualization has to maximally use the potential of the used media. The design of the OO software system and its attributes are represented in the visualization. Class information, relationships between classes, and metric information is displayed. VRML is used for the visualization and it is rendered in the CAVE environment.