Theseus: Whole updates of java server applications

We present a novel approach to update server applications in Java. In our approach, different versions of the code coexist in the system, but are isolated into distinct contexts. The server can switch from one context to another incrementally in order to process incoming requests. Our approach has the following characteristics: (1) updatability is defined and added to the application by developers, (2) no syntax is added to the language and the update is controlled via the manipulation of objects, (3) the whole system is migrated lazily and eventually replaces the old system, (4) it is safe to update global entities anytime and there is no need to reach update points. We demonstrate our approach by updating the Jetty web server.