Abstractions for programming SIP back-to-back user agents

In SIP services, back-to-back user agents (B2BUAs) are powerful but difficult to program correctly. StratoSIP is a high-level, domain-specific language for programming SIP B2BUAs safely. This paper describes the four major abstractions on which the language is based. It explains how each abstraction is used in programming, and how it is implemented in SIP. Because the abstractions are derived from the Distributed Feature Composition (DFC) architecture, Strato-SIP programs compose easily with each other at runtime. The implementation of StratoSIP runs in SIP Servlet containers.