If you haven't installed node.js, socket,io, express and the other helper programs make sure you do that before attempting to run the program below. The installation directions can be found in my previous post. The first app I tried was the simple chat. Two files make up the application: the nodejs file, app.js, and the webpage file, index.html. Place both files into the same directory. (I suggest ~/Documents/nodejs/) Make sure port 8080 is open and available on your server then run
node app.jsThis will start the node.js service. If all is ok you will see status messages in the terminal that will update with each socket event. If there is a failure the prompt will be returned to you. Fire up a web browser and navigate to your server's address. (In my case it looks like http://192.168.0.12:8080) After a moment you will receive a java prompt asking for a chat user name. After entering a name you will be placed in the chat and can send a receive messages from anyone else connected. Most likely you will be the only one connected so fire up a second web browser to mimic a second chat connection.
The node.js file app.jsvar app = require('express').createServer()
var io = require('socket.io').listen(app);
app.listen(8080);
// routing
app.get('/', function (req, res) {
res.sendfile(__dirname + '/index.html');
});
// usernames which are currently connected to the chat
var usernames = {};
io.sockets.on('connection', function (socket) {
// when the client emits 'sendchat', this listens and executes
socket.on('sendchat', function (data) {
// we tell the client to execute 'updatechat' with 2 parameters
io.sockets.emit('updatechat', socket.username, data);
});
// when the client emits 'adduser', this listens and executes
socket.on('adduser', function(username){
// we store the username in the socket session for this client
socket.username = username;
// add the client's username to the global list
usernames[username] = username;
// echo to client they've connected
socket.emit('updatechat', 'SERVER', 'you have connected');
// echo globally (all clients) that a person has connected
socket.broadcast.emit('updatechat', 'SERVER', username + ' has connected');
// update the list of users in chat, client-side
io.sockets.emit('updateusers', usernames);
});
// when the user disconnects.. perform this
socket.on('disconnect', function(){
// remove the username from global usernames list
delete usernames[socket.username];
// update list of users in chat, client-side
io.sockets.emit('updateusers', usernames);
// echo globally that this client has left
socket.broadcast.emit('updatechat', 'SERVER', socket.username + ' has disconnected');
});
});<script src="/socket.io/socket.io.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"></script>
<script>
var socket = io.connect('http://23.21.164.48:8080');
// on connection to server, ask for user's name with an anonymous callback
socket.on('connect', function(){
// call the server-side function 'adduser' and send one parameter (value of prompt)
socket.emit('adduser', prompt("What's your name?"));
});
// listener, whenever the server emits 'updatechat', this updates the chat body
socket.on('updatechat', function (username, data) {
$('#conversation').append('<b>'+username + ':</b> ' + data + '<br>');
});
// listener, whenever the server emits 'updateusers', this updates the username list
socket.on('updateusers', function(data) {
$('#users').empty();
$.each(data, function(key, value) {
$('#users').append('<div>' + key + '</div>');
});
});
// on load of page
$(function(){
// when the client clicks SEND
$('#datasend').click( function() {
var message = $('#data').val();
$('#data').val('');
// tell server to execute 'sendchat' and send along one parameter
socket.emit('sendchat', message);
});
// when the client hits ENTER on their keyboard
$('#data').keypress(function(e) {
if(e.which == 13) {
$(this).blur();
$('#datasend').focus().click();
}
});
});
</script>
<div style="float:left;width:100px;border-right:1px solid black;height:300px;padding:10px;overflow:scroll-y;">
<b>USERS</b>
<div id="users"></div>
</div>
<div style="float:left;width:300px;height:250px;overflow:scroll-y;padding:10px;">
<div id="conversation"></div>
<input id="data" style="width:200px;" />
<input type="button" id="datasend" value="send" />
</div>Next learn how to control real-time interactions with node.js and socket.io