Application Composition in the SIP Servlet Environment

The SIP servlet standard is a popular Java application programming interface (API) for developing and deploying session initiation protocol (SIP) applications in Voice over IP (VoIP) environments. A number of commercial container implementations conforming to the current 1.0 specification are available; they provide feature rich and robust environments where a wealth of SIP applications can provide flexible control logic for advanced telecommunications applications. However, while one of the stated goals of the SIP servlet API is to support application composition, it is optional and not standardized in the 1.0 specification. In this paper, the authors propose an application composition framework that is general, powerful, and yet shields developers of individual applications from the complexities of application composition and feature interaction. Such a framework promotes modularity and application reuse. Also presented here are the results of implementing this framework on top of 1.0 implementations. This framework is being standardized for the new 1.1 SIP Servlet specification as part of the JCP JSR 289 process.