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EASY: An event/association centric simulation framework

Charles Suscheck
( USA )

Colorado Technical University
2110 Westmoreland Rd. Colorado Springs, CO 80907 USA
tel: 01-719-594-6142
fax:
csuscheck@acm.org

Keywords:

analysis/design frameworks simulations

Abstract:

Using current optimistic parallel discrete event simulation (OPDES) frameworks to implement an object-oriented domain model disassociates the domain design from the actual implementation. Much of the disconnect is due to the events and constructs introduced to support associations. It is very common for simulations to form and dissolve thousands of associations over the execution of a scenario. Implementing associations in a manner that reflects the conceptual domain model is critical to the quality of an object-oriented simulation model. My dissertation proposes an OPDES package that reduces complexity by specifically supporting association formation. The design of this simulation package can be applied to other PDES frameworks to support associations and reduce the complexity of using framework, thereby keeping the system implementation close to the design. The expectations for high speed, high fidelity, accurate, and understandable computer simulations is increasing. Frameworks for parallel simulation provide a significant increase in throughput of events, which enables more detail in the simulation model without sacrificing performance. The fidelity and performance of the simulation is increased which leads to an increase in the complexity of the domain model. The high degree of complexity of the model makes it important to employ techniques that ease systems development. One of the most efficient techniques for developing an accurate and understandable domain model has proven to be object-oriented modelling. Associations are a very important part of the domain model in many simulations. Associations are dynamically formed and dissolved. For example, a phenomenon s such as "radar detects missile" causes an association between a radar and a missile object to be formed. Current object-oriented OPDES frameworks hide the complexities of parallelism and optimism at the cost of using events to manipulate objects, which leaves the manipulation of association in the hands of the modeler. It becomes necessary to add classes and events that do not map to the domain design in order to support associations. I propose an OPDES package (EASY) that hides the implementation classes and events that must otherwise be included to manipulate associations. Through junction objects, container classes, and support mechanism specifically designed to manipulate associations, the simulation package separates the dynamic association-based interactions that objects play from their context-independent behavior. This separation allows the domain modeler to concentrate on the behavior of the domain and opens up the design to a cleaner, more understandable, and more reusable implementation. With the package the implementation level model becomes less complex and matches the conceptual domain model more closely. My hypothesis is that a simulation framework designed to support associations (EASY) will display characteristics of reduced complexity when compared to representative OPDES frameworks. To this end, I select and then apply a set of object-oriented complexity metrics to a domain model implemented in representative simulation frameworks. I show that the baseline domain model exhibits higher complexity when implemented in the comparison frameworks than in EASY. The development of EASY is based on direct support of associations within simulation frameworks such as IMPORT, language level support of associations such as proposed in Smalltalk, and the use of design patterns.

The PhD work started: 10/1999

The participant will apply for the
upcoming ECOOP PhD Workshop.

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Last modified on Mon Aug 15 14:59:24 2005