Websocketpp is a C++ implementation of the websocket protocol. Websockets allow bidirectional communications between the server and the client, in opposition to HTTP where all communications are initiated by the client. Please note that the source code Websocketpp is not provided by silicon. You need to install it by yourself before compiling silicon-websocketpp code.
The websocketpp silicon backend enables the server to remotely call function on the set of client connected clients. It implements a very basic protocol to serialize and send the calling data (function path and arguments) back to the client.
The example wsbroadcastserver.cc shows how to build a simple broadcast chat with silicon and it's websocketpp backend.