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37
Abstracting a Specification from Code
, 1993
"... Much of the work on developing program transformation systems has concentrated on systems to assist in program development. However, the four separate surveys carried out between 1977 and 1990 [18,20,22,24], summarised in [17], show that between 40% and 60% of all commercial software effort is devot ..."
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Cited by 44 (18 self)
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Much of the work on developing program transformation systems has concentrated on systems to assist in program development. However, the four separate surveys carried out between 1977 and 1990 [18,20,22,24], summarised in [17], show that between 40% and 60% of all commercial software effort is devoted to software maintenance rather than the development of new systems. In this paper we describe a joint project between the University of Durham and CSM Ltd to develop a method and tool for reverse engineering and software maintenance based on program transformation theory. We present an example which illustrates how such a tool can extract a highlevel abstract specification from the lowlevel source code of a program by a process of formal program transformation based on a theory of program equivalence [27]. All the codelevel reverse engineering of the example progr...
Assembler to C Migration using the FermaT Transformation System
 In IEEE International Conference on Software Maintenance (ICSM’99
, 1999
"... The FermaT transformation system, based on research carried out over the last twelve years at Durham University and Software Migrations Ltd., is an industrialstrength formal transformation engine with many applications in program comprehension and language migration. This paper describes one applic ..."
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Cited by 42 (8 self)
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The FermaT transformation system, based on research carried out over the last twelve years at Durham University and Software Migrations Ltd., is an industrialstrength formal transformation engine with many applications in program comprehension and language migration. This paper describes one application of the system: the migration of IBM 370 Assembler code to equivalent, maintainable C code. We present an example of using the tool to migrate a small, but complex, assembler module to C with no manual intervention required. We briefly discuss a mass migration exercise where 1,925 assembler modules were sucessfully migrated to C code. Keywords: Assembler, Migration, Comprehension, Formal Methods, WSL, Wide Spectrum Language, Program Transformation, Legacy Systems, Restructuring.
Foundations for a Practical Theory of Program Refinement and Transformation
, 1994
"... A wide spectrum language is presented, which is designed to facilitate the proof of the correctness of refinements and transformations. Two different proof methods are introduced and used to prove some fundamental transformations, including a general induction rule (Lemma 3.9) which enables transfor ..."
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Cited by 21 (14 self)
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A wide spectrum language is presented, which is designed to facilitate the proof of the correctness of refinements and transformations. Two different proof methods are introduced and used to prove some fundamental transformations, including a general induction rule (Lemma 3.9) which enables transformations of recursive and iterative programs to be proved by induction on their finite truncations. A theorem for proving the correctness of recursive implementations is presented (Theorem 3.21), which provides a method for introducing a loop, without requiring the user to provide a loop invariant. A powerful, general purpose, transformation for removing or introducing recursion is described and used in a case study (Section 5) in which we take a small, but highly complex, program and apply formal transformations in order to uncover an abstract specification of the behaviour of the program. The transformation theory supports a transformation system, called FermaT, in which the applicability conditions of each transformation (and hence the correctness of the result) are mechanically verified. These results together considerably simplify the construction of viable program transformation tools; practical consequences are briefly discussed.
Pigs from Sausages? Reengineering from Assembler to C via FermaT Transformations
 Science of Computer Programming, Special Issue on Program Transformation 52
, 2004
"... Software reengineering has been described as being "about as easy as reconstructing a pig from a sausage" [11]. But the development of program transformation theory, as embodied in the FermaT transformation system, has made this miraculous feat into a practical possibility. This paper desc ..."
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Cited by 21 (5 self)
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Software reengineering has been described as being "about as easy as reconstructing a pig from a sausage" [11]. But the development of program transformation theory, as embodied in the FermaT transformation system, has made this miraculous feat into a practical possibility. This paper describes the theory...
Formal Methods to Aid the Evolution of Software
 International Journal of Software Engineering and Knowledge Engineering
, 1995
"... There is a vast collection of operational software systems which are vitally important to their users, yet are becoming increasingly difficult to maintain, enhance and keep up to date with rapidly changing requirements. For many of these so called legacy systems the option of throwing the system awa ..."
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Cited by 19 (5 self)
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There is a vast collection of operational software systems which are vitally important to their users, yet are becoming increasingly difficult to maintain, enhance and keep up to date with rapidly changing requirements. For many of these so called legacy systems the option of throwing the system away an rewriting it from scratch is not economically viable. Methods are therefore urgently required which enable these systems to evolve in a controlled manner. The approach described in this paper uses formal proven program transformations, which preserve or refine the semantics of a program while changing its form. These transformations are applied to restructure ans simplify the legacy systems and to extract higherlevel representations. By using an appropriate sequence of transformations, the extracted representation is guaranteed to be equivalent to the code. The method is based on a formal wide spectrum language, called WSL, with accompanying formal method. Over the last ten years we h...
Slicing as a Program Transformation
 ACM Transactions On Programming Languages and Systems
, 2007
"... The aim of this paper is to provide a unified mathematical framework for program slicing which places all slicing work, for sequential programs, on a sound theoretical foundation. The main advantage to a mathematical approach is that it is not tied to a particular representation. In fact the mathema ..."
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Cited by 15 (3 self)
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The aim of this paper is to provide a unified mathematical framework for program slicing which places all slicing work, for sequential programs, on a sound theoretical foundation. The main advantage to a mathematical approach is that it is not tied to a particular representation. In fact the mathematics provides a sound basis for any particular representation. We use the WSL (Wide Spectrum Language) program transformation theory as our framework. Within this framework we define a new semantic relation, semirefinement which lies between semantic equivalence and semantic refinement. Combining this semantic relation, a syntactic relation (called reduction) and WSL’s remove statement, we can give mathematical definitions for backwards slicing, conditioned slicing, static and dynamic slicing and semantic slicing as program transformations in the WSL transformation theory. A novel technique of “encoding ” operational semantics within a denotational semantics allows the framework to handle “operational slicing”. The theory also enables the concept of slicing to be applied to nondeterministic programs. These transformations are implemented in the industrystrength FermaT transformation system.
Do Program Transformations Help Reverse Engineering?
 In IEEE International Conference on Software Maintenance (ICSM'98
, 1998
"... Program transformations have been advocated as a method for accomplishing reverse engineering. The hypothesis is that the original source code can be progressively transformed into alternative forms, but with the same semantics. At the end of the process, an equivalent program is acquired, but one w ..."
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Cited by 13 (0 self)
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Program transformations have been advocated as a method for accomplishing reverse engineering. The hypothesis is that the original source code can be progressively transformed into alternative forms, but with the same semantics. At the end of the process, an equivalent program is acquired, but one which is much easier to understand and more maintainable. We have been undertaking an extensive programme of research over twelve years into the design and development of transformations for the support of software maintenance. The paper very briefly explains the theory, practice and tool support for transformational systems, but does not present new theoretical results. The main results are on an analysis of the strengths and weaknesses of the approach, based on experience with case studies and industrial applications. The evaluation framework used (called DERE) is that presented in [5]. It is hoped that the results will be of benefit to industry, who might be considering using the technolog...
Reverse Engineering from Assembler to Formal Specifications via Program Transformations
, 2000
"... ..."
Language Oriented Programming
 In: Software  Concepts and Tools, Springer Berlin / Heidelberg, Vol.15, No.4
, 1994
"... This paper describes the concept of language oriented programming which is a novel way of organising the development of a large software system, leading to a different structure for the finished product. The approach starts by developing a formally specified, domainoriented, very highlevel languag ..."
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Cited by 13 (3 self)
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This paper describes the concept of language oriented programming which is a novel way of organising the development of a large software system, leading to a different structure for the finished product. The approach starts by developing a formally specified, domainoriented, very highlevel language which is designed to be wellsuited to developing “this kind of program”. The development process then splits into two independent stages: (1) Implement the system using this “middle level ” language, and (2) Implement a compiler or translator or interpreter for the language, using existing technology. The approach is claimed to have advantages for domain analysis, rapid prototyping, maintenance, portability, userenhanceable systems, reuse of development work, while also providing high development productivity. We give an example where the method has been used very successfully (in conjunction with rapid prototyping) in the development of a large software system: the FermaT reverse engineering tool. A major benefit of this approach to software development, as compared to the usual sequential “waterfall model ” is the speed with which products can be brought to market. This is due to “concurrent engineering”: the effective overlap of development stages. Finally, the “middle out ” development
Formal Methods for Legacy Systems
 J. Software Maintenance: Research and Practice
, 1995
"... A method is described for obtaining useful information from legacy code. The approach uses formal proven program transformations, which preserve or refine the semantics of a construct while changing its form. The applicability of a transformation in a particular syntactic context is checked before a ..."
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Cited by 11 (3 self)
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A method is described for obtaining useful information from legacy code. The approach uses formal proven program transformations, which preserve or refine the semantics of a construct while changing its form. The applicability of a transformation in a particular syntactic context is checked before application. By using an appropriate sequence of transformations, the extracted representation is guaranteed to be equivalent to the code. In this paper, we focus on the results of using this approach in the reverse engineering of medium scale, industrial software, written mostly in languages such as assembler and JOVIAL. Results from both benchmark algorithms and heavily modified, geriatric software are summarised. It is concluded that the approach is viable, for self contained code, and that useful design information may be extracted from legacy systems at economic cost. We conclude that formal methods have an important practical role in the reverse engineering process.