International Journal of Software Engineering and Knowledge Engineering

Genesis is a software system generator for database management systems that relies exclusively on as-is large scale component reuse. We review the general model of software components on which Genesis is based and discuss component libraries for relational database systems that we have implemented. We then explain how we have evolved Genesis and its libraries to be able to synthesize object-oriented database systems. We study a subproblem of creating “self-tuning” software systems by examining the performance of selected components for object-oriented database systems.

Related reusable components are often based on different conceptual models of behavior. This may unduly restrict the ways in which they can be composed. The conceptual model underlying the specification of one module’s parameter requirements may differ significantly from the model underlying the specification of another module’s exported features, even if the two modules intuitively seem compatible. There is no well understood groundwork of common models for component interaction, and the lack of guidance for applying these models exacerbates the composability problem. This article describes how varying interface models and techniques for describing a component’s interface requirements affect composability. These problems are illustrated in the context of common interface properties that are exhibited even in simple ADT components.

For widespread reuse in a component-based software industry, a component must be designed and developed to be reused. Benefits of reuse are maximized when a component is reused “as is” (possibly with provisions for expected customization, such as through parameters), based only on its specification. The expression of the specification of a component is crucial in this setting. The specification must be formal, yet understandable, as well as abstract and implementation-independent. The specification also must make it possible to demonstrate correctness of an implementation of the specification and permit formal reasoning about its behavior in a client program. This paper explains how it is possible to write specifications with these properties in RESOLVE, a conceptual framework that we have developed for constructing reusable software components.

A multidatabase system (MDBS) is a system that integrates several autonomous database systems and provides users with a uniform access to all the databases. In this paper we developed a two-level active metadata dictionary approach for semantic query processing. To capture the global view of data schemas of participating databases which may be heterogeneous, a Hornclause data model is used. The lower-level metadata dictionaries (LLMDs) keep metadata for each corresponding local database in MDBS. The higher-level metadata dictionary (HLMD) integrates the metadata about all LLMDs. The database integration strategy includes two phases: schema translation and schema integration. It is a bottom-up approach integrating schema from the underlying database schemas. The evaluation strategy is a top-down approach. It starts with a query as a global goal to be achieved, unifies and optimizes the query to decompose the goal into subgoals that can be evaluated against extensional database, then translates these subgoals into corresponding queries against underlying DBMSs. To solve the control problem, we employ a G-net model for procedure control and inference control. An experimental implementation in Prolog is described.

Since its introduction in 1969, the phrase “frame problem” has been attributed various interpretations. Most researchers in the field of Artificial Intelligence define the frame problem as the problem of finding an effective representation for reasoning about change. Logicians use the phrase to refer to a much less general technical problem within logic whereas philosophers tend to interpret the phrase as the more general problem of determining (ir)relevance. All in all, this discrepancy has led to considerable confusion about the meaning of the phrase. We contend that most of this confusion can be avoided, if the original (robotics) context of the frame problem is adhered to. We present an engineering view on the frame problem that allows us to strip the frame problem from associated problem notions like qualification and ramification. The problem that remains is intimately related to the knowledge acquisition bottleneck in knowledge engineering.

Inspite of numerous research advancements made in recent years in the area of formal techniques, specification of real-time systems is still proving to be a very challenging and difficult problem. In this context, this paper critically examines state-of-the-art specification techniques for real-time systems and analyzes the emerging trends.