| Abstract: | This paper presents a modular design approach for the implementation of process-oriented or event-oriented discrete systems simulation software. Requirements for such a simulation facility are discussed, to include list processing capabilities, data structuring capabilities, dynamic allocation of data storage, statistics collection and number-crunching capabilities, and subprograms. Specific focus is placed upon implementing the process view which requires constructs in the language for initiating, controlling and terminating a process. Resource management facilities are also considered, to include a means of defining a resource with its associated resource handler and a set of primitives for requesting, releasing and obtaining status information regarding a resource. HPSIM, an organized collection of modules written in Modula-2, was designed to facilitate both event-oriented and process-oriented discrete systems simulation, Modula-2 was chosen for its data abstraction facilities, its software engineering capabilities, its execution efficiency, its ability for separate compilation and its implementation of co-routines. The modeller encapsulates the conceptual model of the system into a software module which is interfaced with the HPSIM modules. The IMPORT statement in Modula-2 allows the modeller to access any of the routines provided by HPSIM as required. An example involving a single-server CPU system highlights the process/resource features of HPSIM. |
