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layout: post title: Socket IO date: 2019-02-12 —

Socket.IO

Is a library that enables real-time, bidirectional and event-based communication between the browser and the server. It consists of:

• a Node.js server: Source

  API

• a Javascript client library for the browser (which can be also run from Node.js): Source

  API

Reliability

Connections are established even in the presence of:

• proxies and load balancers.

• personal firewall and antivirus software.

• For this purpose, it relies on Engine.IO, which first establishes a long-polling connection, then tries to upgrade to better transports that are “tested” on the side, like WebSocket. Please see the Goals * section for more information.

example

io.on(‘connection’, function(socket){ socket.emit(‘request’, /* /); // emit an event to the socket io.emit(‘broadcast’, / /); // emit an event to all connected sockets socket.on(‘reply’, function(){ / */ }); // listen to the event });