Proceedings of the 2002 Winter Simulation Conference

Is it really true that simulation models and simulation software should always be regarded as candidates for reuse, or is it better to be selective? What are the obstacles to simulation software and model reuse? Can these be surmounted and, if so, at what cost? There is a range of levels at which simulation software may be reused, a range of costs to be borne and range of benefits that may be achieved. It is crucial to consider the issue of validity when considering model reuse and this needs to be a fundamental part of any reuse strategy. There may be circumstances in which reuse is economic, especially when a small, lowfidelity model will suffice. 1 SOFTWARE AND MODEL REUSE Software reuse is the isolation, selection, maintenance and utilisation of existing software artifacts in the development of new systems (Reese and Wyatt, 1987). Any survey of current literature will reveal that there are many different approaches to achieving this end. Although much attention has focused on the reuse of source code level artifacts, reuse can be productively applied to all stages of development. This may involve any element of a system, including entities from requirements specification, design, implementation and testing (Reese and Wyatt, op cit). This paper concentrates on code and model reuse, rather than the other elements. 1.1 A Reuse Spectrum Figure 1 shows a spectrum of different types of software reuse, cast in terms that are recognisable to the simulation community. It shows 4 positions on a very non-linear scale with two different horizontal axes. The first, frequency, indicates that reuse is much more frequent at the right-hand end of the spectrum, where all of us engage in code scavenging. The second axis, complexity, runs in the opposite direction, making the point that code scavenging is relaFull model reuse Component reuse Function reuse Code scavenging