Distributed object-oriented discrete event simulation

This paper presents criteria for an \u27ideal\u27 simulation language, compares four traditional simulation languages to this ideal and concludes that an object-oriented approach to simulation comes closer to the ideal than the traditional procedural approach. It also examines how the object-oriented approach can be very beneficial for distributing a simulation problem among several machines. A distributed object-oriented package is described and a manufacturing example written and explained using this package

A graphics driven approach to discrete event simulation.

This thesis investigates the potential of computer graphics in providing for a graphics driven specification system that gives sufficient structure and content to form the simulation model itself. The nature of discrete event simulation modelling, the diagramming method of activity cycle diagrams which underpinned this research, the three phase simulation model structure, and the trend of visual simulation modelling are discussed as the basis for the research. Some current existing simulation languages and packages are reviewed, which gives insight into the essential features of an ideal computer simulation environment. The basic research method adopted was to build systems that exemplified the state of thinking at the time. The purpose of this method was to enable ideas to be developed, discarded and enhanced, and for new ideas to emerge. The research has undergone a series of application developments on the Apple Macintosh to examine the advantages and limitations of such systems. The first system developed during the research, MacACD, provides the basis for proposals concerning the enhancement of the ACD diagramming method in a computer-aided environment. However, MacACD demonstrated the limitations of an ACD interface and the need for a more flexible specification system. HyperSim, a simulation system developed using HyperCard, has all the power of interconnectivity demonstrated as a need by MacACD, but has severe limitations both in terms of security of system development, and an inability to provide a running model directly due to lack of speed. However, the power of an icon-based interconnected textual and diagrammatic based system were demonstrated by the construction of this system during this research, and led to the development of the final system described in this thesis : MacGraSE. The development of this system during this research incorporates many innovations. The main input device is a picture representing the problem, including a background display. This system allows for dynamic icon based visual model running, as well as code generation for complete model embellishments, interactive report writing, and representational graphics outputs