A program slicing method for a wide spectrum language

This thesis describes the implementation of a program slicer for WSL - a Wide Spectrum Language - which is a language that allows different levels of abstraction to coexist in the same program. WSL contains constructs not found in conventional languages, e.g. action systems (which model a segment of code with GOTOs and labels) and non deterministic constructs. Program slicing is a method for restricting a program to a specified behaviour of interest. Usually this behaviour of interest is expressed in terms of a variable or a set of variables. The method used in the thesis to slice a program is different from the classical ones in that slices do not need to be computed from an output statement, and in that slices are computed on a wide spectrum language closer to a functional language, instead of being computed on a more conventional, procedural language. A slicer for a subset of WSL has been designed and implemented based on the data flow analysis techniques for while-programs of Bergeretti and Carré [10]. It has been necessary to modify the algorithm to permit incremental slicing. Modifications of their algorithm were also needed to accommodate the specific WSL constructs mentioned above. The implementation has been developed using a rapid prototyping approach. The prototype has provided new ideas and enhancements for a more comprehensive sheer which could be implemented in the future. The slicer has assisted the maintainer using ReForm - a reverse engineering project developed at Durham University - in understanding and debugging a program by decomposing it. At the end of this thesis results showing how slicing has helped the maintainer are presented. Conclusions on the method used, the validity of the tool, and its engineering are also summarized

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

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

A Conceptual Design for Smell Based Augmented Reality: Case Study in Maintenance Diagnosis

The trend of Industry 4.0 encourages the next generation of manufacturing to be flexible, intelligent, and interoperable. The implementations of the Artificial Intelligence (AI) technology could potentially enhance maintenance in efficiency, and accuracy. However, it will not be a substitution to the human operator's flexibility, decision-making and information received by the natural five senses. Augmented reality (AR) is commonly understood as a technology that overlays virtual information onto the existing environment to provide users a new and improved experience to assist their daily activities. However, AR can be used to enhance all human five senses rather than just overlay virtual imagery. In this paper, a design and a practical plan of smell augmentation for diagnosis is initialised, via a case study in maintenance. The aim of this paper is to evaluate the feasibilities, identify challenges, and summarise initial results of overlaying information through smell augmentations

Proceedings of the 1994 Monterey Workshop, Increasing the Practical Impact of Formal Methods for Computer-Aided Software Development: Evolution Control for Large Software Systems Techniques for Integrating Software Development Environments

Office of Naval Research, Advanced Research Projects Agency, Air Force Office of Scientific Research, Army Research Office, Naval Postgraduate School, National Science Foundatio

Support for an integrated approach to program understanding: an application of software visualisation

Program Comprehension is a key factor in providing effective software maintenance and enabling successful evolution of software systems. The objective of this research is to provide a framework and mechanism to facilitate the understanding of large software systems. There exist a number of theories and models of Program Comprehension where each favours a different approach to comprehension. It is evident that there is no real consensus on how maintainers understand software systems. The disparities in the comprehension strategies are largely dependent on the personal and circumstantial factors. Factors such as the level of technical competence of the maintainers, the size and complexity of the piece of software, and the types and goals of the maintenance activities can influence the process of comprehension. This research proposes an alternative approach to Program Comprehension. It acknowledges that the process of comprehension is opportunistic, and that the current comprehension theories are inadequate in addressing this. There is a need for a more flexible approach towards comprehension, and the Integrated Approach proposed in this thesis provides a way for the utilisation of the various comprehension theories under a single environment. It recognises that any one of the comprehension theories may become active during comprehension. Under the Integrated Approach, maintainers have the option of selecting and executing the various comprehension strategies as they see fit. The Integrated Approach to comprehension is based on a matrix of Program Relationships between Program Elements of a programming language. In this thesis, these Program Relationships are derived for the C programming language constructs. This work also involves the investigation of the roles of both textual and graphical representations during the comprehension process. Both representations are commonly used to alleviate the problem of information overloading when maintainers trying to understand and maintain a software system. The Integrated Approach is realised in a tool named PUI (program [understanding implements) which provides an environment enabling the utilisation of various comprehension theories

Requirements for a software maintenance support environment

This thesis surveys the field of software maintenance, and addresses the maintenance requirements of the Aerospace Industry, which is developing inige projects, running over many years, and sometimes safety critical in nature (e.g. ARIANE 5, HERMES, COLUMBUS). Some projects are collaborative between distributed European partners. The industry will have to cope in the near and far future with the maintenance of these products and it will be essential to improve the software maintenance process and the environments for maintenance. Cost effective software maintenance needs an efficient, high quality and homogeneous environment or Integrated Project Support Environment (IPSE). Most IPSE work has addressed software development, and lias not fully considered the requirements of software maintenance. The aim of this project is to draw up a set of priorities and requirements for a Maintenance IPSE. An IPSE, however can only support a software maintenance method. The first stage of this project is to deline 'software maintenance best practice' addressing the organisational, managerial and technical aspects, along with an evaluation of software maintenance tools for Aerospace systems. From this and an evaluation of current IPSEs, the requirements for a Software Maintenance Support Environment are presented for maintenance of Aerospace software

Qualitative Analysis for Maintenance Process Assessment

In order to improve software maintenance processes, we first need to be able to characterize and assess them. These tasks must be performed in depth and with objectivity since the problems are complex. One approach is to set up a measurement-based software process improvement program specifically aimed at maintenance. However, establishing a measurement program requires that one understands the problems to be addressed by the measurement program and is able to characterize the maintenance environment and processes in order to collect suitable and cost-effective data. Also, enacting such a program and getting usable data sets takes time. A short term substitute is therefore needed. We propose in this paper a characterization process aimed specifically at maintenance and based on a general qualitative analysis methodology. This process is rigorously defined in order to be repeatable and usable by people who are not acquainted with such analysis procedures. A basic feature of our approach is that actual implemented software changes are analyzed in order to understand the flaws in the maintenance process. Guidelines are provided and a case study is shown that demonstrates the usefulness of the approach. (Also cross-referenced as UMIACS-TR-96-7

A study of the methodologies currently available for the maintenance of the knowledge-base in an expert system

This research studies currently available maintenance methodologies for expert system knowledge bases and taxonomically classifies them according to the functions they perform. The classification falls into two broad categories. These are: (1) Methodologies for building a more maintainable expert system knowledge base. This section covers techniques applicable to the development phases. Software engineering approaches as well as other approaches are discussed. (2) Methodologies for maintaining an existing knowledge base. This section is concerned with the continued maintenance of an existing knowledge base. It is divided into three subsections. The first subsection discusses tools and techniques which aid the understanding of a knowledge base. The second looks at tools which facilitate the actual modification of the knowledge base, while the last secttion examines tools used for the verification or validation of the knowledge base. Every main methodology or tool selected for this study is analysed according to the function it was designed to perform (or its objective); the concept or principles behind the tool or methodology: and its implementation details. This is followed by a general comment at the end of the analysis. Although expert systems as a rule contain significant amount of information related to the user interface, database interface, integration with conventional software for numerical calculations, integration with other knowledge bases through black boarding systems or network interactions, this research is confined to the maintenance of the knowledge base only and does not address the maintenance of these interfaces. Also not included in this thesis are Truth Maintenance Systems. While a Truth Maintenance System (TMS) automatically updates a knowledge base during execution time, these update operations are not considered \u27maintenance\u27 in the sense as used in this thesis. Maintenance in the context of this thesis refers to perfective, adaptive, and corrective maintenance (see introduction to chapter 4). TMS on the other hand refers to a collection of techniques for doing belief revision (Martin, 1990) . That is, a TMS maintains a set of beliefs or facts in the knowledge base to ensure that they remain consistent during execution time. From this perspective, TMS is not regarded as a knowledge base maintenance tool for the purpose of this study

Runtime visualisation of object-oriented software

Software is a complex and invisible entity, yet one which is core to modem life. The development and maintenance of such software includes one staple task, the need to understand the software at the implementation level. This process of program comprehension is difficult and time consuming. Yet, despite its importance, there remains very limited tool support for program comprehension activities. The results of this research show the role that runtime visualisation can play in aiding the comprehension of object-oriented software by highlighting both its static and dynamic structure. Previous work in this area is discussed, both in terms of the representations used and the methods of extracting runtime information. Building on this previous work, this thesis develops new representations of object-oriented software at runtime, which are then implemented in a proof of concept tool. This tool allowed the representations to be investigated on real software systems. The representations are evaluated against two feature-based evaluation frameworks. The evaluation focuses on generic software visualisation criteria, due to the lack of any specific frameworks for visualising dynamic information. The evaluation also includes lessons learnt in the implementation of a prototype visualisation tool. The object-oriented paradigm continues to grow in popularity and provides advantages to program comprehension activities. However, it also brings a number of new challenges to program comprehension due to the discrepancies between its static definition and its runtime structure. Therefore, techniques that highlight both the static definition and the runtime behaviour of object-oriented systems offer benefits to their comprehension. Software visualisation offers an approach to aid program comprehension activities through providing a means to deal with the size and complexity of the software and its invisible nature. This thesis highlights the generic issues that software visualisation faces, before focusing on how the visualisation of runtime information affects these issues. Many of the issues are compounded by the dynamic nature of the information to be visualised and the explosive growth in the volume of information that this dynamism can bring. Wider results of this research have allowed the proposal of the necessary concepts that should be considered in the design and evaluation of runtime visualisations. Software visualisation at runtime is still a relatively unexplored area and there remains many research challenges within it. This thesis aims to act as a first step to addressing these challenges and aims to promote interest and future development within this area