Oldschool Socket Communication

This post describes a simple example for implementing sockets. Sockets allow two programs to communicate across a network. It does this by allocated a unique port number to the program. This enables multiple networked programs to run from a single operating system, and allows fully-duplex data transmission. This is opposed to the web-based “Client/Server” paradigm, which traditionally only allowed data communication to be instantiated by the client (Web browser) in the form of a HTTP request. The server (software on a networked computer) could then respond to the request.

Only recently bi-directional communication within the web browser was made possible thanks to the WebSocket protocol.

The following is a simple example of how to network a piece of software, and how to receive and send data. In this example the server will wait for an instruction to perform a particular task, and then respond when the task is complete. In the above code you will notice that a client has established a connection and sent a request “calculate_primes:2000000”, this will be interpreted on the other node as “find all the prime numbers in 200000”.

The server receives the request, performs the task and responds to the request when the task is complete.