Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering
Transport Technology / Logistic Engineering

R. den Ouden Simulatie met Java®.
Computer program, Report 97.3.LT.4902, Transport Technology, Logistic Engineering.

Java is a computer language which importance is increasing by its use for internet. Several simulation tools for Java are available, such as SimJava or JavaSim, but none of these tools make Java a programming language suitable for discrete-event simulation. My computer assignment was to develop a simulation-tool for Java which includes the event scheduler. Subsequently a standard simulation problem, the 'lock model' had to be programmed which makes use of the simulation unit developed. De simulation methods of the simulation unit have to correspond to the terminology and principles of Must.

After getting acquainted to and gaining programming experience with Java I started programming the lock model. While programming, for each simulation method like 'start', '(re)activate', 'passivate', 'hold' and 'stop', a separate method (Java-term for procedure) was developed. In the end a collection of simulation methods was formed, so only these simulation methods had to be saved in a new package (Java-term for unit). This package makes it possible to use these simulation methods in every Java-program by initializing the package in the class-definition (the syntax of the class). While developing the simulation program is decided to use a class of the thread-type for each component. The usage of the threads makes it possible to stop each component temporarily while running the simulation, which is essential for the discrete-event simulation. Since Java supports the usage of multi-threading (running several threads simultanious), it was of great importance to take care of the fact that while running the simulation, only one thread is active at a time, because of the discrete-event principle.

Conclusions with regard to the development of the simulation unit and the usage of Java are: Although the developed simulation-unit makes it possible to program and simulate the lock model in Java, the simulation-unit is far from complete, reliable and user-friendly like simulation tools as Must or Prosim. Therefore the following recommendations are made:

Reports on Logistic Engineering (in Dutch)
Modified: 2000.04.15; , TU Delft / 3mE / TT / LT.