Acquiring data designs from existing data-intensive programs

The problem area addressed in this thesis is extraction of a data design from existing data intensive program code. The purpose of this is to help a software maintainer to understand a software system more easily because a view of a software system at a high abstraction level can be obtained. Acquiring a data design from existing data intensive program code is an important part of reverse engineering in software maintenance. A large proportion of software systems currently needing maintenance is data intensive. The research results in this thesis can be directly used in a reverse engineering tool. A method has been developed for acquiring data designs from existing data intensive programs, COBOL programs in particular. Program transformation is used as the main tool. Abstraction techniques and the method of crossing levels of abstraction are also studied for acquiring data designs. A prototype system has been implemented based on the method developed. This involved implementing a number of program transformations for data abstraction, and thus contributing to the production of a tool. Several case studies, including one case study using a real program with 7000 Hues of source code, are presented. The experiment results show that the Entity-Relationship Attribute Diagrams derived from the prototype can represent the data designs of the original data intensive programs. The original contribution of the thesis is that the approach presented in this thesis can identify and extract data relationships from the existing code by combining analysis of data with analysis of code. The approach is believed to be able to provide better capabilities than other work in the field. The method has indicated that acquiring a data design from existing data intensive program code by program transformation with human assistance is an effective method in software maintenance. Future work is suggested at the end of the thesis including extending the method to build an industrial strength tool

Software maintenance by program transformation in a wide spectrum language

This thesis addresses the software maintenance problem of extracting high-level designs from code. The investigated solution is to use a mathematically-based formal program transformation system. The resulting tool, the Maintainer's Assistant, is based on Ward's [177] WSL (wide spectrum language) and method of proving program equivalence. The problems addressed include: how to reverse engineer from code alone (the only reliable source of information about a program [158]), how to express program transformations within the system, what kinds of transformations should be incorporated, how to make the tool simple to use, how to perform abstraction and how to create a tool suitable for use with large programs. Using the Maintainer's Assistant, the program code is automatically translated into WSL and the transformations, although tested for valid applicability by the system, are interactively applied by the user. Notable features include a mathematical simplifier, a large flexible transformation catalogue and, significantly, the use of an extension of WSL, A4etaWSL, for representing the transformations. MetaWSL expands WSL by incorporating a variety of extensions, including: program editing statements, pattern matching and template filling functions, symbolic mathematics and logic functions, statements for moving within the program’s syntax tree and statements for repeating an operation at each node of the tree. Using MetaWSL, 80% of the 601 transformations can be expressed in less than 20 program statements. The Maintainer's Assistant has been used on a wide variety of examples of up to several thousand lines, including commercial software written in IBM 370 assembler. It has been possible to transform initially unstructured programs into a hierarchy of procedures, facilitating subsequent design recovery. These results show that program transformation is a viable method of renovating old (370 assembler) code in a cost elective way, and that MetaWSL provides an effective basis for clearly and concisely expressing the required transformations