  Discrete EVent Specification (DEVS) environments are known to be implemented
over middleware systems such as HLA, RMI, CORBA and others. DEVS exhibits
concepts of systems theory and modeling and supports capturing the system
behavior from the physical and behavioral perspectives. Further, they are
implemented using Object-oriented languages like Java and C++. This research
work uses the Java platform to implement DEVS over a Service Oriented
Architecture (SOA) framework. Called the DEVS/SOA, the framework supports a
development and testing environment known as DEVS Unified Process that is built
on a model-continuity-based life cycle methodology. DEVS Unified Process allows
DEVS-based Modeling and Simulation (M&S) over net-centric platforms using
DEVS/SOA. This framework also provides the crucial feature of run-time
composability of coupled systems using SOA. We describe the architecture and
designs of the both the server and the client. The client application
communicates with multiple servers hosting DEVS simulation services. These
Simulation services are developed using the proposed symmetrical services
architecture wherein the server can act as both a service provider and a
service consumer contrary to the unidirectional client-server paradigm. We also
discuss how this Services based architecture provides solutions for
cross-platform distributed M&S. We demonstrate DEVS/SOA framework with a
scenario of Joint Close Air Support specified in Business Process Modeling
Notation (BPMN). We also provide a real-world application of Network health
monitoring using DEVS/SOA layered architectural framework.
