A number of new generation languages have been evolved for the past few years and have been adapted by the industries. As a result of which the project done under 3GL are becoming Legacy and also the information that is to be stored is increasing the complexity of the Legacy systems. These are issues because of which companies are migrating their legacy systems to SOA which provides loosely coupled and interoperable services. There are many approaches to migrate a legacy system to SOA. This paper presents a survey to migrate legacy system to SOA. We also propose a roadmap to migrate a legacy system to service oriented architecture.