Using Analogy and Formal Methods for Software Reuse

Using formal speciications to represent software components facilitates the determination of reusability because they more precisely characterize the func-tionality of the software, and the well-deened syntax makes processing amenable to automation. This paper presents an approach, based on formal methods, to the modiication of reusable software components. From a two-tiered hierarchy of reusable software components, the candidate components that are analogous to the query speciication are retrieved from the hierarchy. A retrieved component is compared to the query speciication to determine what changes needed to be applied to the corresponding program component in order to make it satisfy the query speciication. The major objectives of a reuse system are to classify the reusable components, to retrieve them from an existing library, and to modify the retrieved components to satisfy the query speciication. In previous investigations, the processes for classifying software components to form hierarchy of corresponding speciications and retrieving software components have been formally speciied and implemented 1, 3, 4]. Analogical reasoning has long been recognized as an important tool to overcome the search complexity of nding solutions to novel problems 2]. Retrieved components may not exactly match the query spec-iication. Analogy presents a basic and challenging question: when are two speciications (problem representations) for a given purpose, alike? Analogical reasoning techniques are used to enhance our software reuse system. This paper describes an approach to modifying retrieved components based on analogies between existing and query speciications. A top-down matching process to facilitate the modiication process based on analogies between a pair of components has been added to the reuse system. The remainder of this paper is organized as follows. Section 2 deenes analogical matching. Section 3 describes the matching algorithm used in the analogical reasoning process. Section 4 demonstrates an example application of the matching algorithm. Section 5 describes related work in the area of applying analogy to software engineering problems. Section 6 gives concluding remarks and brieey describes future investigations. An analogical match is a group of associated pairs between symbols in the logical terms term 1 and term 2 that belong to base and target speciications, respectively. Each pair in an analogical match is of the following form: ((symbol 1 ; position 1); (symbol 2 ; position 2)) where symbol 1 is located at position 1 of logical term term 1 , and similarly for symbol 2 , position 2 , and term 2. The analogical matching …