James D. Mooney’s research while affiliated with West Virginia University and other places

The Variable Language Interpreter (VALI) is a high-level-language computer architecture. The language definition is not fixed, but can be easily changed to process many popular languages. The languages may be complete, so portable programs can be handled. VALI makes use of parallel processors to achieve its objectives. Parsing is carried out by an array of identical units called token processors. These generate a high-level intermediate form called an execution tree. This tree is then interpreted by additional processors, exploiting its parallelism whenever possible. A version of this design has been simulated. Suitable implementation methods are discussed.

Portability is becoming universally recognized as a desirable attribute for most software products, and porting is a recognized technique for extending the value and life of a software unit. However, most porting is still done by ad hoc techniques. Portability is not addressed explicitly either by software engineering curricula or by common software development methodologies. Moreover, there are few reports in the literature of academic research focused on portability issues. Many studies deal with reuse issues, and porting is a special case of reuse. However, these studies have not addressed the specialized problems of reuse across substantially different operating environments. A portability research group has been established at West Virginia University to help meet this need. Our overall goal is to develop improved methodologies for addressing portability in a cost-effective way for a wide range of software. A major obstacle to meeting this goal is the lack of established mechanisms to specify and measure portability. In this presentation we propose some initial approaches to the development of such mechanisms. We first describe briefly the issues that arise in developing portable software, and in reimplementing or porting existing software. This analysis is used to identify specification types and metrics that may aid in making effective portability-related decisions when performing these activities. We argue the need for specifications to describe interfaces and environmental attributes and to characterize the "degree of portability" of a software unit. Some approaches to formalizing these concepts are discussed. Cost metrics for software development and porting activities are also discussed, and we consider their use in comparing development and implementation alternatives. A formal definition for degree of portability is proposed, and some relevant software quality measures are briefly considered. Some simple examples are also presented to illustrate these concepts.