Reuse of requirements reduced time to market at one industrial shop: a case study
Many a computer-based system (CBS) developed in one division of the Israel Aerospace Industries, is a derivation of formerly delivered CBSs. Sometimes, a CBS that was developed over decades needs to be redesigned for a new customer or for new technology. In addition, the requirements management process in the division has to deal with an extensive system of systems, a matrix organizational structure, and many subcontractors in order to develop any fully operational CBS. It has become obvious that any generic building block in any product developed by any project in a project family stands a chance to be reused to build new products in other projects of the same project family. Moreover, this reuse is best if it begins with the consideration of the reuse of a requirements specification of the building block, in order to save the time and money of the blocks development. The reused artifact can be the contract description of the building block, from very early in the lifecycle. Alternatively, the reused artifact can be detailed hardware and software specifications for the building block, from later in the lifecycle. With which specification reuse begins depends on the purpose of the reuse. No matter when a reuse began, it led to some significant reduction in the products time to market, i.e., its time to delivery. This paper is a case study of several instances in an industrial setting of building-block reuse within a large-scale system being developed in the division. It reports how these reuses were discovered and carried out. Among the contributions of this paper is a description of the divisions multilevel requirements hierarchy that is based on the multilevel architecture of the CBS to be developed. Also contributed the divisions idea of project-family-based reuse, as opposed to product-line-based reuse. The paper shows how basing reuse on a project family made proactive reuse possible. The paper then analyzes data from the divisions requirements-management tool about these reuses to assess the impact of requirements reuse on time to market. Finally, it confirms this quantitative assessment by a qualitative assessment garnered from quotations gathered from interviews of four key people two-and-a-half years after the end of the period of the case study.
reuse requirements requirements management management process project family specifications large-scale system tools reusable software