The Code-Map Metaphor - A Review Of Its Use Within Software Visualisations

Software developers can use software visualisations employing the code-map metaphor to discover and correlate facts spread over a large code base. This work presents an extensive review of the use of the code-map metaphor for software visualisation. The review analyses a set of 29 publications, which together describe 21 software development tools that use visualisations employing the code-map metaphor. The review follows a task oriented framework to guide the analysis of the literature in terms of the task, audience, target, medium, representation, and evidence dimensions based on the code-map metaphor. Although the literature indicates that software visualisations based on the code-map metaphor are perceived by the research community to be helpful across all aspects of the software develop process, the main finding of our review is that there is a lack of quantitative evidence to support this perception. Thus, the effectiveness of visualisations incorporating the code-map metaphor is still unclear. The majority of the software visualisations analysed in this study, however , do provide qualitative observations regarding their usage in various scenarios. These are summarised and presented in this review as we believe the observations can be used as motivation for future empirical evaluations

Animating the evolution of software

The use and development of open source software has increased significantly in the last decade. The high frequency of changes and releases across a distributed environment requires good project management tools in order to control the process adequately. However, even with these tools in place, the nature of the development and the fact that developers will often work on many other projects simultaneously, means that the developers are unlikely to have a clear picture of the current state of the project at any time. Furthermore, the poor documentation associated with many projects has a detrimental effect when encouraging new developers to contribute to the software. A typical version control repository contains a mine of information that is not always obvious and not easy to comprehend in its raw form. However, presenting this historical data in a suitable format by using software visualisation techniques allows the evolution of the software over a number of releases to be shown. This allows the changes that have been made to the software to be identified clearly, thus ensuring that the effect of those changes will also be emphasised. This then enables both managers and developers to gain a more detailed view of the current state of the project. The visualisation of evolving software introduces a number of new issues. This thesis investigates some of these issues in detail, and recommends a number of solutions in order to alleviate the problems that may otherwise arise. The solutions are then demonstrated in the definition of two new visualisations. These use historical data contained within version control repositories to show the evolution of the software at a number of levels of granularity. Additionally, animation is used as an integral part of both visualisations - not only to show the evolution by representing the progression of time, but also to highlight the changes that have occurred. Previously, the use of animation within software visualisation has been primarily restricted to small-scale, hand generated visualisations. However, this thesis shows the viability of using animation within software visualisation with automated visualisations on a large scale. In addition, evaluation of the visualisations has shown that they are suitable for showing the changes that have occurred in the software over a period of time, and subsequently how the software has evolved. These visualisations are therefore suitable for use by developers and managers involved with open source software. In addition, they also provide a basis for future research in evolutionary visualisations, software evolution and open source development

Visualising The Complex Features Of Source Code

Software development is a complex undertaking composed of several activities that include reading, writing, and modifying source code. Indeed, previous studies have shown that the majority of the effort invested in software development is dedicated to understanding code. This includes understanding the static structure, dynamic behaviour, and evolution of the code. Given these particular characteristics, as well as the high complexity of source code, it is reasonable to consider how visualisation can facilitate source code understanding. This work proposes to extend existing software development tools with visualisations that can be used to encode the various complex features within a source code document. Further, this work establishes a design space which includes a series of visualisations that are meant to complement existing textual views of source code, as found in source code editors. Several prototype visualisations are presented in this work which utilise various visualisation techniques, such as tree visualisations techniques and visualisation techniques based on the code-map metaphor. This work also presents several experiments, where the results of these experiments indicate that combining existing software development tools with visualisations can have a positive effect on source code understanding. Additionally, the result of the experiments show that the less a visualisation is abstracted from the original textural representation of a source code document, in terms of line, token, ordering, and character information, the more likely it is that viewers can link the visualisation to the code and back

The Code Mini-Map Visualisation: Encoding Conceptual Structures Within Source Code

Modern source code editors typically include a code mini-map visualisation, which provides programmers with an overview of the currently open source code document. This paper proposes to add a layering mechanism to the code mini- map visualisation in order to provide programmers with visual answers to questions related to conceptual structures that are not manifested directly in the code. Details regarding the design and implementation of this scope information layer, which displays additional encodings that correspond to the scope chain and information related to the scope chain within a source code document, is presented. The scope information layer can be used by programmers to answer questions such as: to which scope does a specific variable belong, and in which scope is the cursor of the source code editor currently located in. Additionally, this paper presents a study that evaluates the effectiveness of adding the scope information layer to a code mini-map visualisation in order to help programmers understand scope relationships within source code. The results of the study show that the incorporating additional layers of information onto the code mini-map visualisation can have a positive effect on code understanding

Virtual software in reality

Software visualisation is an important weapon in the program comprehension armoury. It is a technique that can, when designed and used effectively, aid in understanding existing program code. It can achieve this by displaying information in new and different forms, which may make obvious something missed in reading the code. It can also be used to present many aspects of the data at once. Software, despite many software engineering advances in requirements, design and implementation techniques, continues to be complex and large and if anything seems to be growing in these respects. This means that techniques that failed to aid comprehension and maintenance are certainly not going to be able to deal with the current software. Therefore this area requires research to be able to suggest solutions to deal with the information overload that is sure to occur. There are several issues that this thesis addresses; all of them related to the creation of software visualisation systems that are capable of being used and useful well into the next generation of software systems. The scale and complexity of software are pressing issues, as is the associated information overload problem that this brings. In an attempt to address this problem the following are considered to be important: abstractions, representations, mappings, metaphors, and visualisations. These areas are interrelated and the first four enable the final one, visualisations. These problems are not the only ones that face software visualisation systems. There are many that are based on the general theory of the applicability of the technique to such tasks as program comprehension, rather than the detail of how a particular code fragment is shown. These problems are also related to the enabling technology of three- dimensional visualisations; virtual reality. In summary the areas of interest are: automation, evolution, scalability, navigation and interaction, correlation, and visual complexity. This thesis provides an exploration of these identified areas in the context of software visualisation. Relationships that describe, and distinguish between, existing and future software visualisations are presented, with examples based on recent software visualisation research. Two real world metaphors (and their associated mappings and representations) are defined for the purpose of visualising software as an aid to program comprehension. These metaphors also provide a vehicle for the exploration of the areas identified above. Finally, an evaluation of the visualisations is presented using a framework developed for the comparative evaluation of three-dimensional, comprehension oriented, software visualisations. This thesis has shown the viability of using three-dimensional software visualisations. The important issues of automation, evolution, scalability, and navigation have been presented and discussed, and their relationship to real world metaphors examined. This has been done in conjunction with an investigation into the use of such real world metaphors for software visualisation. The thesis as a whole has provided an important examination of many of the issues related to these types of visualisation in the context of software and is therefore a valuable basis for future work in this area

The Code Mini-Map Visualisation - Encoding Conceptual Structures Within Source Code

Modern source code editors typically include a code mini-map visualisation, which provides programmers with an overview of the currently open source code document. This paper proposes to add a layering mechanism to the code mini-map visualisation in order to provide programmers with visual answers to questions related to conceptual structures that are not manifested directly in the code

Visualising software in cyberspace

The problems of maintaining software systems are well documented. The increasing size and complexity of modern software serves only to worsen matters. Software maintainers are typically confronted with very large and very complex software systems, of which they may have little or no prior knowledge. At this stage they will normally have some maintenance task to perform, though possibly little indication of where or how to start. They need to investigate and understand the software to some extent in order to begin maintenance. This understanding process is termed program comprehension. There are various theories on program comprehension, many of which put emphasis on the construction of a mental model of the software within the mind of the maintainor. These same theories hypothesise a number of techniques employed by the maintainer for the creation and revision of this mental model. Software visualisation attempts to provide tool support for generating, supplementing and verifying the maintainer’s mental model. The majority of software visualisations to date have concentrated on producing two dimensional representations and animations of various aspects of a software system. Very little work has been performed previously regarding the issues involved in visualising software within a virtual reality environment. This research represents a significant first step into this exciting field and offers insight into the problems posed by this new media. This thesis provides an identification of the possibilities afforded byU3D graphics for software visualisation and program comprehension. It begins by defining seven key areas of 3D software visualisation, followed by the definition of two terms, visualisation and representation. These two terms provide a conceptual division between a visualisation and the elements of which it is comprised. This division enables improved discussion of the properties of a 3D visualisation and particularly the idenfification of properties that are desirable for a successful visualisation. A number of such desirable properties are suggested for both visualisations and representations, providing support for the design and evaluation of a 3D software visualisation system. Also presented are a number of prototype visualisations, each providing a different approach to the visualisation of a software system. The prototypes help demonstrate the practicalities and feasibility of 3D software visualisation. Evaluation of these prototypes is performed using a variety of techniques, the results of which emphasise the fact that there is substantial potential for the application of 3D graphics and virtual reality to software visualisation

Scoped: Evaluating A Composite Visualisation Of The Scope Chain Hierarchy Within Source Code

This paper presents two studies that evaluate the effectiveness of a software visualisation tool which uses a com- posite visualisation to encode the scope chain and information related to the scope chain within source code. The first study evaluates the effectiveness of adding the composite visualisation to a source code editor to help programmers understand scope relationships within source code. The second study evaluates the effectiveness of each individual component within the composite visualisation. The composite visualisation is composed of a packed circle tree diagram (overview component) and a list view (detail view component). The packed circle tree functions as an abstract mini-map to provide viewers with a high-level overview of the scope chain hierarchy within a source code document. The list view provides additional information about identifiers (variables, functions, and parameters) that are accessible from the scope within which the cursor is located, in the source code document. Both studies utilise a between-subject design, in which groups of participants were presented with source code fragments and asked to answer a series of code understanding questions. The results of the studies indicate that adding a composite visualisation to a source code editor can have a positive effect on code understanding, especially when the textual representation of the code no longer corresponds to the actual behaviour of the code (as is the case, for example, in languages such as JavaScript that implement variable hoisting)