T. Dean Hendrix

An extensible framework for providing dynamic data structure visualizations in a lightweight IDE

A framework for producing dynamic data structure visualizations within the context of a lightweight IDE is described. Multiple synchronized visualizations of a data structure can be created with minimal coding through the use of an external viewer model. The framework supplies a customizable viewer template as well as high-level APIs to a graph drawing library and the Java Debugger Interface. Initial classroom use has demonstrated the frameworks ease of use as well as its potential to as an aid to student learning.

Experimental evaluation of animated-verifying object viewers for Java

Although many visualization techniques have been shown to be pedagogically effective, they are still not widely adopted. The reasons include: lack of suitable methods of automatic-generation of visualizations, lack of integration among visualizations, and lack of integration with basic integrated development environment (IDE) support. To effectively use visualizations when developing code, it is useful to automatically generate multiple synchronized views without leaving the IDE. The jGRASP IDE provides object viewers that automatically generate dynamic, state-based visualizations of objects and primitive variables in Java. Such seamless integration of a lightweight IDE with a set of pedagogically effective software visualizations is unique and is currently unavailable in any other environment. Multiple instructors have reported positive anecdotal evidence of their usefulness. We conducted formal, repeatable experiments to investigate the effect of these viewers for singly linked lists on student performance and we found a statistically significant improvement over traditional methods of visual debugging that use break-points.

The Control Structure Diagram: An Overview and InitialEvaluation

A new graphical representation, the Control Structure Diagram (CSD), has been created to visualize software at both the source code and program design language (PDL) level. The primary impetus for creation of the CSD was to improve the comprehension efficiency of software and, as a result, improve reliability and reduce costs. The CSD has the potential to replace traditional prettyprinted source code. As part of the GRASP (Graphical Representations of Algorithms, Structures, and Processes) research project at Auburn University, the GRASP software engineering tool has been successfully developed. GRASP automatically generates CSDs from source code written in Ada, C, C++, Java, and VHDL. The emphasis to this point has been on the automatic generation of the CSD to support development, maintenance, reverse engineering and reengineering through the use of GRASP. GRASP has been applied successfully to numerous programs ranging in size from several hundred to several thousand lines of source code and is efficient and sufficiently flexible for use in a production setting. To demonstrate the potential benefits of the CSD and its automatic generation using GRASP, a series of empirical studies has been planned and initiated. First, as reported in this article, the perceived usefulness of the CSD was evaluated using a preference instrument based on eleven performance characteristics in which a comparison was made with other well-known graphical representations for algorithms. Statistical analysis indicated numerous significant differences with a clear preference for the CSD in seven of the eleven performance characteristics. Further empirical studies, currently being implemented, will examine the effect of the CSD and GRASP on objective measures such as comprehension efficiency and effectiveness.

Implementing studio-based learning in CS2

This paper presents an experience in designing, implementing, and evaluating a studio-based learning model for CS2. Adapted from architecture and art education, as well as from collaborative problem-solving pedagogies, studio-based learning has shown great promise for computing education. Key elements of studio-based learning include exploring multiple solutions to a problem, justifying the choice of one solution, and being subject to, as well as providing, peer reviews. We describe the design, implementation, and revision of a studio model for CS2, and then present the results of an evaluation of the model when compared to traditional instruction in CS2.

Language independent generation of graphical representations of source code

There are many potential benefiti to be gained from the effective we of graphical representatiom of source code. To be of practical we, however, ruch graphical representations mwt be automatically generated and supported in aoftware. There are e&tiny tools that provide this functionality, but many are source language specific. That is, they can only be wed with source code written in, say, Ada. A source language independent tool that automatically generates control structure diagrams from source code is the authors’ first step towarda a suite of language independent code visualization and software engineering tools. The graphical representation generator worb in two phases: the markup phase and the rendering phase. During the markup phase, a parser for a given source language is used to embed generic markup tags in the source tezt. In the rendering phase, the embedded tags provide all the needed information for producing the control structure diagram.

Robust Generation of Dynamic Data Structure Visualizations with Multiple Interaction Approaches

jGRASP has three integrated approaches for interacting with its dynamic viewers for data structures: debugger, workbench, and text-based interactions that allow individual Java statements and expressions to be executed/evaluated. These approaches can be used together to provide a complementary set of interactions with the dynamic viewers. Data structure identification and rendering were tested by examining examples from 20 data structure textbooks. Controlled experiments with CS2 students indicate that the viewers can have a significant positive impact on student performance. The overall result is a flexible environment for interacting with effective dynamic data structure visualizations generated by a robust structure identifier.

Studio-based learning in CS2: an experience report

Recently there has been a surge of interest in making computer science education attractive to potential students, motivating to current students, and relevant to graduating students. We are exploring a new pedagogical approach called studio-based learning as a means to reinvigorate computer science education. Adapted from architectural education, this instructional model emphasizes learning activities in which students (a) design computational solutions to problems that lend themselves to multiple solution strategies, and (b) present and justify their solutions to their instructors and peers for critical review and discussion. In this paper we describe the studio-based approach, discuss how it was implemented in CS2, and present preliminary evaluation results.

The role of software measures and metrics in studies of program comprehension

Many studies have been conducted into how programmers comprehend software. Models based on these studies have pointed to top-down, bottom-up, and mixed models for describing the comprehension process. In most of these studies, however, a key element of the experiment is largely ignored: the underlying nature of the software being examined by the programmers. This paper discusses software measurements and metrics that must be considered as factors when conducting comprehension

Qualitative comparison of systems facilitating data structure visualization

The development of pedagogically sound learning tools using software visualization (SV) techniques has been a very popular area of research. In this paper we will conduct a qualitative comparison of a few such tools with an emphasis on data structure visualization. There are numerous tools available in academia to aid in the instruction of introductory level data structures. In this paper, we will evaluate a representative sample of these tools using Prices SV taxonomy and suggest improvements that can be incorporated in future work.

Visual support for incremental abstraction and refinement in Ada 95

1. ABSTRACT GRASP is a software engineering tool which uniquely combines a source code diagramming technique, the control structure diagram (CSD), with other comprehension aids such as complexity visualization, syntax coloring and source code folding. The synergistic combination of these features in GRASP has the potential to be a powerful aid in any activity where source code is expected to be read. The primary focus of GRASP is to improve the comprehension efficiency of software and, as a result, improve reliability and reduce costs during design, implementation, testing, maintenance and reengineering.