International Journal of Software Engineering and Knowledge Engineering

Object-oriented analysis is the activity of understanding a problem domain and developing a specification for it within an object-oriented paradigm. In this paper we propose object-oriented analysis can be viewed as a design task that consists of analysis, synthesis and internal and external completeness and consistency checking. We postulate a blackboard based design framework and propose several alternative theories within this framework. Data from an expert analyst is collected and analyzed for relative explanatory power of the alternative theories. Basic findings are that viewed as a design activity, object-oriented analysis is neither top-down nor completely opportunistic in nature, Rather, (1) analysis (the process of finding objects and processes) and synthesis (constructing the object model and state-transition diagrams) are complementary activities while internal completeness and consistency checking is coupled with synthesis and (2) construction of objects and processes are cyclic and complementary processes. The findings are compared with both descriptive and normative research in automated software design.

Reusing software may greatly increase the productivity of software engineers and improve the quality of developed software. Software component libraries have been suggested as a means for facilitating reuse. A major difficulty in designing software libraries is in the selection of a component representation that will facilitate the classification and the retrieval processes. Using formal specifications to represent software components facilitates the determination of reusable software because they more precisely characterize the functionality of the software, and the well-defined syntax makes processing amenable to automation.

This paper presents an approach, based on formal methods, to the classification, organization and retrieval of reusable software components. From a set of formal specifications, a two-tiered hierarchy of software components is constructed. The formal specifications represent software that has been implemented and verified for correctness. The lower-level hierarchy is created by a subsumption test algorithm that determines whether one component is more general than another; this level facilitates the application of automated logical reasoning techniques for a fine-grained, exact determination of reusable candidates. The higher-level hierarchy provides a coarse-grained determination of reusable candidates and is constructed by applying a hierarchical clustering algorithm to the most general components from the lower-level hierarchy. The hierarchical organization of the software component specifications provides a means for storing, browsing, and retrieving reusable components that is amenable to automation. In addition, the formal specifications facilitate the verification process that proves a given software component correctly satisfies the current problem. A prototype browser that provides a graphical framework for the classification and retrieval process is described.

Assumption-based truth maintenance systems (ATMS) have become powerful and widely used tools in artificial intelligence problem solvers. In this paper, we apply ATMS to verification of termination of computer programs written as a set of rewrite rules. Compared with the traditional methods based on the ordinary backtracking, our method can greatly improve the overall efficiency by virtue of the ATMS's ability to avoid futile backtracking, rediscovering inferences, and rediscovering contradictions. The originality of our work lies in the practical use of the ATMS in a software engineering problem and in the communication protocol between the termination verifier and the ATMS.

Current programming languages support construction of parameterized reusable components that can be adapted and composed to create new functionality. For widespread reuse, software components must also have readily adaptable performance. This paper introduces language mechanisms for creating such performance-parameterized reusable software components and for controlling their performance by "plugging in" appropriate constituent components. A key element of the proposed approach is that it provides inexpensive performance tuning. It permits performance of a tunable component to be changed without modifications to the functionality of the component or its clients; in principle, without the need for re-compilation or re-validation of functionality.

Knowledge bases contain specific and general knowledge. In relational database systems, specific knowledge is often represented as a set of relations. The conventional methodologies for centralized database design can be applied to develop a normalized, redundancy-free global schema. Distributed database design involves redundancy removal as well as the distribution design which allows replicated data segments. Thus, distribution design can be viewed as a process on a normalized global schema which produces a collection of fragments of relations from a global database. Clearly, not every fragment of data can be permitted as a relation. In this paper, we clarify and formally discuss three kinds of fragmentations of relational databases, and characterize their features as valid designs, and we introduce a hybrid knowledge fragmentation as the general case. For completeness of presentation, we first show an algorithm for the validity test of vertical fragmentations of normalized relations, and then extend it to the more general case of unbiased fragmentations.

This paper summarizes the author's four-year research on examining rule-based programming (RBP) and object-oriented programming (OOP) for expert systems implementation. It reaches two conclusions. First, with a few exceptions, RBP is simply not working in practice. Second, many rule-based problems can be solved with OOP with improved system understandability and maintainability. This paper aims at (1) clarifying some of the confusion surrounding expert systems technology, and (2) providing a practical direction for expert systems implementation.