Service extraction and application composition may include preprocessing and instrumenting an existing application that is to be converted to a service-oriented application. The existing application may be executed to generate traces related to a runtime behavior of services related to the existing application. The traces may be used to generate calling code related to the services related to the existing application. Representational state transfer (REST) application programming interfaces (APIs) that include the calling code to call the services related to the existing application may be generated. Refactored code for the existing application may be generated for invocation of the services related to the existing application by the REST APIs.