OSGi is about to become the predominant standard in Enterprise Java and for good reasons. But like any other new technology introducing it inside existing environments can be challenging. This talk shows the benefits of OSGi in Enterprise Java, the concrete challenges and solutions to them. The focus is on the SpringSource dm Server that represents a complete OSGi environment and solves many of the issues in this area. Throughout the talk several demos and code samples will show the pratical application of the shown principles. This includes the stepwise migration of a (legacy) WAR based web applications to a fully modularized OSGi based web application.