Using WebSockets

This recipe will show you how to use WebSockets in a client-server application (both web and command-line clients) and what its advantages are. You can find the code in the project websockets.

Getting ready

HTTP is a simple request-response-based protocol, and then the connection is broken from the application's point of view until the next request. In a modern web application (for example, in online multiplayer games), the client and server are of equal importance; changes in the state of the application can take place on both sides. So, we need a bi-directional communication channel between the client(s) and the server that allows for two-way real time updates and more interaction; this is exactly what WebSockets has to offer. WebSocket connections between a browser and a server are made through a handshake request. This is a regular HTTP client request with an upgrade flag in the header, also containing a Sec-WebSocket-Key, which is a random value that has been base64 encoded...