As I explained back in Chapter 1, the web application pulls data from a web server. The client initiates the transfer by sending a request to the server. The response is then rendered in the browser. All web application design is based on this request/response paradigm. However, WebSocket technology opens up a whole new world, allowing server-initiated communication with client applications.
Socket technology is not new. Sockets have been used for decades as an effective protocol for point-to-point communication between applications. The exciting news, however, is that the W3C has included a WebSocket API specification as ...