The Workflow Management System, which is widely recognized as an effective tool, greatly improves the efficiency of business process. The challenges for workflow management systems rely on their ability to align ICT and the new paradigms of businesses. Unfortunately, they suffer from some lacks and limitations due to their architectures, enterprise platform dependences as well as a lack of standards. In this paper, we propose a generic distributed, adaptive and platform independent Workflow architecture based on a Service Oriented approach (SOA) and the WfMC reference model. Hence, the architecture hinges on autonomy, distributed and self-contained web services. The assembly of the services is centered in a crucial Web Service known as the orchestrator service. We validate our architecture based on the Service Oriented approach and web services by implementing a preliminary prototype.