Representational state transfer (REST) was introduced in early 2000 by Roy Fielding's doctoral dissertation. However, in the Java community, it was not standardized until JSR 311(JAX-RS) was finalized in 2008. The first release of its reference implementation is even later. In this article, I introduce Jersey, which is the reference implementation of JSR 311, by describing its essential APIs and annotations. I'll also show you how you can smoothly transfer from servlet-style services to RESTful services by integrating Jersey into Apache Tomcat.