Implementation and Evaluation of Scalability Techniques in the Eco Model

Event-based communication is appropriate for many application domains, ranging from small, centralised applications such as GUIs to large, distributed applications such as telecommunications, network monitoring and virtual world support systems. Consequently, many di erent event models have been put forward, some designed for small-scale systems and others for large-scale systems. One such model is the eco model which was designed to support virtual world applications in the Moonlight project. The eco model was designed to be scalable by including ltering capabilities that were intended to decrease network tra c in a distributed implementation. There have been two previous implementations of the eco model, and one characteristic of both was that all code was linked into the application at compile time, regardless of whether it was used at runtime or not. This resulted in executables which were larger than strictly necessary, and consequently lower scalability for applications hosting many objects, most of which were used only on a few nodes. A better approach could be to link code on demand at runtime with the intention of decreasing the application footprint. This thesis describes the design and implementation of a distributed version of the eco model and the evaluation of lters and dynamic linking as means to achieve increased scalability. The evaluation is empirical and real data gathered from an actual event-based system is used. In addition to the design and evaluation chapters, a detailed review of four event models, including the eco model, is provided, with particular emphasis on ltering and dynamic linking.