Application of a Smalltalk-based simulation tool

by Tim Verwaart & John Wolters

From their origin almost half a century ago, object-oriented programming languages have been applied for simulation of real-world systems. The first object-oriented language, Simula, was designed as a language for discrete event simulation. Simula is as good as dead now, but Smalltalk lives. Numerous examples of simulations in Smalltalk illustrate its suitability for simulation of discrete entities that interact with an environment.

In the talk we will give some examples of object-oriented simulations and in particular some successful Smalltalk applications. A special branch of simulation is multi-agent simulation. Agents are software entities that can act autonomously, are goal-driven, responsive to their environment, and social, i.e. they are aware of the existence of other agents, can share information, and adjust their behavior in response to observation and information of other agents. The natural application area of multi-agent simulation is the simulation of social processes. It can be used for two purposes. The first is to support group decision making in interaction with stakeholders, to show the effect of decisions on the behavior of social systems. The second application area are the social sciences by themselves, where multi-agent simulation models can be used to enhance our understanding of social processes. In the talk we will present our experience with CORMAS, a Smalltalk-based system for multi-agent simulation that has been around for ages, but, as we will show, is still a strong tool for rapid development. The subject of our simulation is: the effect that cultural differences have on trade in international supply chains. We will present how Smalltalk has helped us to rapidly create a model and discuss some advantages & disadvantages of Smalltalk for agent modeling.

Bio: Tim and John work for LEI Wageningen UR, a social sciences institute working in the fields of agriculture, rural areas, and food. Both have been involved in Smalltalk systems development for 10 years. Tim was a Simula programmer until 1978. He was very pleased when after 20 years of suffering, a new opportunity for real object orientation emerged in his current job. John has been working on the Smalltalk project at LEI from the beginning. He works with VisualWorks and is the GemStone expert of the team.