The Design And Implementation Of Signal Subsystem Of The Webrtc System

RTCWeb (Real-Time Communication in the Web-browsers) is an effort to achieve a standardized infrastructure in Web browsers on which real-time interactive communication between users of the World Wide Web can be achieved. WebRTC system is a system based on web browser, and the system provides functions such as audio/video calls, instantmessages, address book, presence, group management and make real-time communication with other VoIP systems which use SIP.This paper focuses on the design and implementation of signal subsystem of the WebRTC system. Signal subsystem plays an important role in WebRTC system, which is mainly responsible for media negotiation and session management. The signal protocol used for real-time communication between web browsers is ROAP, which is short of RTCWeb Offer/Answer Protocol. ROAP is sent between browser and WebRTC server over WebSocket and the server should manage the sessions. WebRTC gateway makes the interconriectionbetween WebRTC system and other VoIP systems possible. The signal module of WebRTC gateway needs to control the conversation, and what’s the most, make protocol adaptation between ROAP and SIP. The paper start by presenting designdetail of the signal subsystem, including architecture and modules, signal protocol, session management and so on. Based on the design, the paper shows the implementation of signal subsystem. Finally, by testing the signal subsystem of the WebRTC system, we have evaluated the effectiveness of the signal subsystem.