As computer technology advances, the size and scope of simulations expand. So, too, do the costs of simulation studies, and the idea of simulation as a distinct discipline has appeared, at least in part, as a result of economic forces. Just as the complexity of software reached a crisis in the 1960s (or, more likely, well before this), giving birth to the now well-recognized field of software engineering, the problems posed by large simulation projects are spurring interest in those elements of modeling and simulation that transcend the particular. Software architectures for simulation are one such topic. In this concluding chapter, three other topics are briefly considered; although not conclusive, this short survey includes technologies that are relevant to the construction of simulation software, are being actively pursued at the present, and are likely to have a substantial impact on the future of modeling and simulation.
7.1 SIMULATION PROGRAMMING LANGUAGES
For 40 years, beginning in the 1950s and tapering in the 1990s, simulation programming languages were a major focus of academic and industrial research. Some languages for discrete-event simulation are still widely used, but these appear largely as part of commercial products: SIMAN, MODL, and SLAM, for instance, are the backbones of Arena (Rockwell Automation), Extend (Imagine That!), and Awesim, respectively (see, e.g., Refs. 27, 62, 105, and 112); Raczynsky's PASION (and its more recent variants ...