A High-Level, Open-Ended Architecture For SIP-based Services

Overview & Synopsis

Now that Internet Telephony can interact with systems such as databases, e-mail facilities and Web services, it can offer a host of new functionalities. However, developing enriched, real-size services is quite a challenge considering the requirements that must be fulfilled by the service developer. Such developer must (1) have an extensive knowledge on network protocols and distributed systems; (2) be familiar with often large and complex platform APIs (e.g., JAIN); and (3) fully understand the signaling protocol (e.g., SIP) to develop services that do not compromise the processing of the calls, nor the platform. All these areas of expertise are required by most existing platforms. They offer unrestricted APIs and support mainstream programming languages such as C, C# and Java. They provide little abstraction, and thus rely on the programmer to manage the intricacies of the underlying technologies (protocols, network layers, and signaling). Other platforms enable service creation through a scripting language, such as CPL and LESS, that offers a restricted expressiveness and mostly targets the creation of individual user services. We present a high-level architecture of an Application Server for SIP-based services. Our architecture abstracts over the intricacies of the underlying technologies and facilitates both the development and the management of services. By revolving around an Application Server, our approach allows a uniform and coherent basis of telephony services to be offered to the platform users, regardless of the heterogeneity of their end systems.