1.6 Simulation Languages
Discrete event simulation normally involves a tremendous volume of computation. Consequently, the use of computers to carry out these computations is essential; however, the volume of computations is not the only obstacle in simulation. If you consider the bank teller example discussed in the previous sections, you will discover that it involves a complex logical structure that requires special expertise before it can be translated into a computer model. Attempting to implement the simulation model, from scratch, in a general purpose language such as FORTRAN, Visual Basic, C/C++, or Java will require above average programming skills. In the absence of specialized libraries for these languages that try to relive the user from some of the burden, simulation as a tool would be relegated to "elite" programmers. Luckily, the repetitive nature of computations in simulation allows the development of computer libraries that are applicable to simulation modeling situations. For example, libraries or packages must be available for ordering and processing events chronologically, as well as generating random numbers and automatically collecting statistics. Such a library for simulating discrete-event systems in Java is available from the author, see (Rossetti 2008).
The computational power and storage capacity of computers has motivated the development of specialized simulation languages. Some languages have been developed for continuous or discrete simulations. Others can be used for combined continuous and discrete modeling. All simulation languages provide certain standard programming facilities and will differ in how the user will take advantage of these facilities. There is normally some trade-off between how flexible the language is in representing certain modeling situations. Usually, languages that are highly flexible in representing complex situations require more work (and care) by the user to account for how the model logic is developed. Some languages are more programming oriented (e.g. SIMSCRIPT) and others are more "drag and drop" (e.g. ProModel, Arena, etc. ).
The choice of a simulation language is a difficult one. There are many competing languages, each having their own advantages and disadvantages. The Institute for Operations Research and Management Science (INFORMS) often has a yearly product review covering commercial simulation languages, see for example (http://lionhrtpub.com/orms/). In addition to this useful comparison, you should examine the Winter Simulation Conference (www.wintersim.org). The conference has hands on exhibits of simulation software and the conference proceedings often have tutorials for the various software packages. Past proceedings have been made available electronically through the generous support of the INFORMS Society for Simulation (http://www.informs-sim.org/wscpapers.html).
was chosen for this textbook because of the author’s experience utilizing the software, its ease of use, and the availability of student versions of the software. While all languages have flaws, using a simulation language is essential in performing high performance simulation studies. Most, if not all simulation companies have strong support to assist the user in learning their software. has a strong academic and industrial user base and is very competitive in the simulation marketplace. Once you learn one simulation language well, it is much easier to switch to other languages and to understand which languages will be more appropriate for certain modeling situations.
is fundamentally a process description based language. That is, when using , the modeler describes the process that an "entity" experiences while flowing through or using the elements of the system. You will learn about how facilitates process modeling throughout this textbook.