In this thesis, we present a framework for managing changes in service oriented enterprises (SOEs). A service oriented enterprise outsources and composes its functionality from third-party Web service providers. We focus on changes initiated or triggered by these member Web services. We present a taxonomy of changes that occur in service oriented enterprises. We use a combination of several types of Petri nets to model the triggering changes and ensuing reactive changes. The techniques presented in our thesis are implemented in WebBIS, a prototype for composing and managing e-business Web services. Finally, we conduct an extensive simulation study to prove the feasibility of the proposed techniques. / Master of Science