Source code file that can be compiled by SJavaC, a Java compiler that extends the Java 1.4 specification to support synchronous active objects; contains standard Java source code as well as synchronous active objects, which define threaded processing and locking behaviors. Synchronous Java files are used for event-driven applications, such as GUIs and network-based programs. The SJavaC compiler was written by members of the Computer Networking Laboratory at EPFL, a polytechnic school in Switzerland.