Service Oriented Architectures (SOA) present challenges to current model-based software engineering methodologies such as Rational Unified Process (RUP). In this research effort we propose a process called DEVS Unified Process (DUNIP) that uses the DEVS formalism as a basis for automated generation of models from various requirement specifications and realization as SOA collaborative services. DEVS is inherently based on object oriented methodology and systems theory, and categorically separates the Model, the Simulator and the Experimental frame, and has been used for systems Modeling & Simulation over the years. DUNIP integrates these concepts into DEVSbased Bifurcated Model-Continuity life-cycle development methodology. The life-cycle begins by specifying the system requirements in a number of different formats such as state-based, BPMN/BPEL-based, message-based requirement specifications. DUNIP then automates the generation of DEVS models capable for distributed collaboration. The collaboration uses an XML-based DEVS Modeling Language (DEVSML) framework that provides the capability to integrate models that may be expressed in different DEVS implementation languages. The models are also made available for remote and distributed real-time execution over the SOA middleware in a manner transparent to the user. A prototype simulation framework has been implemented and is illustrated with an application to a system of collaborating military systems implemented and tested using Bifurcated Model-Continuity methodology. We also show how the Department of Defense Architecture Framework (DoDAF) can be enhanced to incorporate simulation based executable models using the DUNIP process.