How Does the Internet Work?

• Your computer asks a server for some data
• The server sends the data back to your computer
• This works great for most things, but what about trying to get data in real time?

Enter WebSockets

• Creates a two-directional connection between your computer and the server
• Both can react to events taking place on the other

Why Socket.io

• A standard way to implement the server end of a WebSocket connection
• Libraries exist for many different types of clients
• Extremely easy to use

emit

• The event taking place
• Sends some data to the other side
• Can be done from client or server

on

• Respond to an event taking place
• Receive data from the other side
• Can be done from client or server

// Client

// Takes the name of the event and
// the data to be sent as parameters

socket.emit('message', {
    sender: 'Alex LaFroscia',
    body:   'This is the message'
});

// Server

// Takes the name of the event and a
// callback as parameters

socket.on('message', function(data) {
  console.log("Sender: " + data.name);
  console.log("Message: " + data.body);
  // The message from the client gets
  // printed to the server
});

The Plan

• Show a list of chat messages on a page
• Have an input box and send button that allow us to add messages