Real-Time Communication with WebRTC

Chapter 5. Putting It All Together: Your First WebRTC System from Scratch

We are finally ready to put all the pieces together and build our first WebRTC application. In this chapter, by leveraging a signaling server like the one we described in Chapter 4, we will implement the Browser RTC Trapezoid in a distributed scenario. Basically, we will take the running example of Chapter 3 and let it also work beyond the limits of a local perspective.

We will show how to use the signaling channel to allow two peers to exchange user media information, session descriptions, and ICE protocol candidates. We will also highlight how the signaling server role proves fundamental only during the setup phase. Indeed, once the above information has been successfully exchanged, the communication paradigm switches to pure peer-to-peer, with the server itself having no involvement in the actual data exchange phases.

A Complete WebRTC Call Flow

Figures 5-1, 5-2, and 5-3 provide the big picture associated with a complete WebRTC call flow involving a channel Initiator, a channel Joiner, and a signaling server relaying messages between them at channel setup time.

Figure 5-1. WebRTC call flow: Sequence diagram, part 1

Figure 5-2. WebRTC call flow: Sequence diagram, part 2

Figure 5-3. WebRTC call flow: Sequence diagram, ...