Socket Examples

The net Library

Example 1 - Creating a Network Socket and talking to it.

node simple_telnet_socket_server then telnet 127.0.0.1 9999

• Anything typed on the telnet client is sent byte-for-byte through the socket.

• This is a TCP Socket that can be used for network communication.

• Visit http://127.0.0.1:9999/path/to/a/resource and look at the header that arrives on the server. The browser is speaking HTTP but our server just sees it as a bunch of bytes. Web servers are just TCP socket servers with code to interpret the HTTP layered on top.

Example 2 - A 404 Server

node simple_404_server.js then open http://127.0.0.1:9999

Since we are in complete control of anything we send over a socket, here we might have the world's smallest responding web server. The short version in simple_404_one_line.js is just 76 characters long.

WebSockets

Example 3 - A WebSocket with an Express HTTP server

node simple_web_socket/server.js then open http://127.0.0.1:9999

Files:

• simple_web_socket_server.js is a minimal web socket server which echoes data sent

  • it is complemented by an Express.js HTTP server that serves files from simple_web_socket_client

• simple_web_socket_client/index.html is a page of two text areas: typing in the left-hand text results in the key codes being sent to the server over a web socket. Any message received from the server is put in the right-hand panel.