I'm using express js & socket.io to built my simple app.
So, there is website "a" using PHP that will post some data to my app (built using express js). There are 2 routes defined in app.js, they are :
/send_voting_result -> Will receive POST data from website "a"
/voting_result -> Will be accessed by user & I want to make it to be realtime in updating the voting result data posted to /send_voting_result
What I did here are :
app.js
var app = require('express')()
, server = require('http').createServer(app)
, io = require('socket.io').listen(server);
...
// Receive POST data and do update the data to /voting_result route
app.post('/send_voting_result', function(req, res){
var result = JSON.parse(req.body.kandidat);
io.of('/voting_result').emit('getResult', {votingResult : result.data});
});
app.get('/voting_result', function(req, res){
res.render('voting_result', { title: 'Express', msg: 'This is Result page'});
});
voting_result.html
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect();
socket.on('getResult', function (data) {
console.log("Message from server : "+data);
});
</script>
However, the "emit" process in this script seems not working :
io.of('/voting_result').emit('getResult', {votingResult : result.data});
I'm unable to retrieve data posted to /send_voting_result in /voting_result
Actually, I'm new in using expressjs & socket.io, so I try my best to achieve it by referring to some related tutorial, but it's still not working.
Is there a proper way to do this?
Thanks in advance
The io.of() method you're using doesn't refer to the URL of the accessed webpage. It instead refers to a namespace that you can define when you create the socket:
// Client-side
var chat = io.connect('http://localhost/chat')
// Server-side
var chat = io
.of('/chat')
.on('connection', function (socket) { ... }) // will only apply to some connections
This feature is used for instance to multiplex multiple data streams on one WebSocket, see Socket.io's documentation, section Restricting yourself to a namespace.
There are then two solutions for your issue:
Don't use namespaces at all:
io.of('/voting_result').emit('getResult', {votingResult : result.data});
becomes
io.emit('getResult', {votingResult : result.data});
Define a namespace on the client, that you'll use on server-side:
var socket = io.connect('/voting_result');
Related
I'm building an application in node, using express for simplify things and socket.io for sockets manipulation.
So, while I'm writing my code I realize that it works, but is not the best and elegant solution.
The only thing I want to do is to wrap all the code of the sockets events, and then reuse in more than one page request, so:
app.js
var express = require('express')
, io;
var app = express()
, PORT = 7777;
io = require('socket.io').listen(app.listen(PORT));
app.get("/", function ( req, res ) {
io.socket.on('connection', function ( socket ) {
socket.on('user', function () {
});
socket.on('message', function () {
});
socket.on('getConversation', function ( socket ) {
});
});
res.render('index');
});
But what happens if I want to assign to the /foo and /bar files the same approach?
i.e. I need to get it in a modular or object oriented way, as can be possible.
There is a pattern to do it?
All you're doing here is attaching event listeners to socket.io after someone makes a page request. Then every single request after that would be attaching new event listeners and your server slowly begins to run out of memory as you clog it with new event listeners every time someone makes a page request. It makes no sense to put socket.io code in your route handlers. Take a look at this:
https://www.npmjs.com/package/express.io
This must have been asked already a thousand times, but I do not find any of the answers satisfying, so I'll try having another go, being as clear as possible.
I am starting out with a clean Express; the one that is usually done via the following terminal commands:
user$ express
user$ npm install
then I proceed installing socket.io, this way:
user$ npm install socket.io --save
on my main.js file I then have the following:
//app.js
var express = require('express'),
http = require('http'),
path = require('path'),
io = require('socket.io'),
routes = require('./routes');
var app = express();
I start my socket.io server by attaching it to my express one:
//app.js
var server = http.createServer(app).listen(app.get('port'), function(){
console.log('express server started!');
});
var sIo = io.listen(server);
What I do now is to set the usual routes for Express to work with:
//app.js
app.get('/', routes.index);
app.get('/send/:recipient/:text', routes.sendMessage);
Now, Since I like to keep things organized, I want to put my socket.io code in another file, so instead of using the usual code:
//app.js
sIo.sockets.on('connection', function(socket){
console.log('got a connection');
});
I use the following to be able to access both the socket and the sIo object (as that object contains all the connections infos (important)):
//app.js
sIo.sockets.on('connection', function(socket){
routes.connection(sIo, socket);
});
// index.js (./routes)
exports.connection = function(sIo, socket){
console.log('got a connection.');
};
This way I can do all my socket.io jobs in here. I know that I can access all my clients information now from the sIo object, but of course, they do not contain any information about their session data.
My questions now are the following:
Suppose a user makes an HTTP request to send a message and the handler in my routes is like this:
exports.sendMessage = function(req, res){
//do stuff here
};
How can I get this to "fire" something in my socket.io to send a message? I do not want to know all the underlying work that needs to be done, like keeping track of messages, users, etc. I only want to understand how to "fire" socket.io to do something.
How can I make sure that socket.io sends the message only to a person in particular and be 100% sure that nobody else gets it? From what I can see, there is no way to get the session infos from the sIo object.
Thanks in advance.
question one: The cleanest way to separate the two would probably be to use an EventEmitter. You create an EventEmitter that emits when an http message comes in. You can pass session information along with the event to tie it back to the user who sent the message if necessary.
// index.js (./routes)
var EventEmitter = require('events').EventEmitter;
module.exports.messageEmitter = messageEmitter = new EventEmitter();
module.exports.sendMessage = function(req, res) {
messageEmitter.emit('private_message', req.params.recipient, req.params.text);
};
question 2: You can access the socket when the initial connection is made. An example mostly borrowed from this answer:
var connect = require('connect'),
userMap = {};
routes.messageEmitter.on('private_message', function(recipient, text) {
userMap[recipient].emit('private_message', text);
});
io.on('connection', function(socket_client) {
var cookie_string = socket_client.request.headers.cookie;
var parsed_cookies = connect.utils.parseCookie(cookie_string);
var connect_sid = parsed_cookies['connect.sid'];
if (connect_sid) {
session_store.get(connect_sid, function (error, session) {
userMap[session.username] = socket_client;
});
}
socket_client.on('private_message', function(username, message) {
userMap[username].emit(private_message, message)
});
});
So we're just creating a map between a session's username and a socket connection. Now whenever you need to send a message you can easily lookup what socket is associated with that user and send a message to them using their socket. Just make sure to handle disconnects, and reconnects and connecting in multiple tabs, etc.
I have built something like what you are saying. If a user can make a socket request, it pushes the message via the socket, and then the server does a broadcast or emit of it. But, if a user can't connect to the socket, it then does the http post, like what you are saying by calling the sendMessage. What I have done, rather than having sendMessage shoot off a socket is that I also have my clients doing an ajax request every 5 seconds or so. That will bring back new messages, and if any of the messages were not received via socket.io, I then add them to my clientside array. This acts as sort of a safety net, so I don't have to always fully trust socket.io.
see below in pseudo code
client
if canSendSocketMessage()
sendSocketMessage(message)
else
sendAjaxMessage(message)
setInterval( ->
// ajax call
getNewMessages()
), 5000
server
socket stuff
socket.on 'message' ->
saveMessage()
socket.emit(message)
ajax endpoints
app.post 'sendMessage'
saveMessage()
app.get 'getNewMessages'
res.send getNewMessages()
I've created a basic node.js server program and used socket.io to pass some field data from a client (see below). Pretty chuffed as I'm new to this business. I liked this node-express-socket.io approach as its all Javascript and is apparently usable by most browsers (incl' mobile). The problem is I've kind of fumbled my way through and do not not fully understand what I have created! Two questions...
1) Do I need to use the "//ajax.googleapis.com...jquery..."? This is annoying as the browser will need to have an internet connection to work. Is there another way to access the html doc elements without needing an internet connection?
2) What does the "app.use(express.static...." line do? The "app.get..." function seems to require this to work.
If there are any other general comments about my code please let me have it!
Cheers,
Kirbs
Client side code:
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect(document.location.protocol+'//'+document.location.host);
function clicked(){
$(function(){
var makeInput=$('.app').find('#make').val();
var modelInput=$('.app').find('#model').val();
socket.emit('make', makeInput);
socket.emit('model', modelInput);
});
};
</script>
Server side code:
var express = require('express');
var http = require('http');
var socketio = require('socket.io');
var app = express();
var server = http.createServer(app);
var io = socketio.listen(server);
app.use(express.static(__dirname));
app.get('/', function (req, res) {
res.render(__dirname + '/index.html');
});
io.sockets.on('connection', function (socket) {
socket.on('make', function (make) {
socket.on('model',function (model){
console.log('recieved message:', make+','+model);
});
});
});
server.listen(8000);
1) As you have setup a static web server (see answer 2), you could simply download the jquery source and serve the .js file from there.
2) "app.use(express.static...." configure a static webserver and setting up the http root directory to the directory that your node.js script lives, as indicated by the __dirname variable. For more detail, see app.use API reference.
As result, I would recommend you change you app.use to:
app.use(express.static(__dirname + '/public'));
and place all your static files, including your jquery file(s), under a public subdirectory.
Also, your server side code has a dependency on sequence of make and model which should be changed. For example, if you switch the emit order to model then make, you should see that your server's console.log will be picking up the make from the previous call.
Instead, try something like:
// On server:
socket.on('info', function (info) {
console.log('recieved message:', info.make+','+info.model);
});
// On client:
socket.emit('info', { make: makeInput, model: modelInput })
1) You can serve the jQuery library also from your server if you like that better. You should put it in the public/vendor or public/js folder in your project.
2) This is a middleware call from Express framework, which uses in turn the Connect middleware stack. Read up on this here.
I am writing a multi-player game using processing.js, node.js and socket.io.
Question #1:
In the client, I use p5.js to create a class Ball.
I want the server to send parameter to create an array using that class (balls.push(new Ball(x, y));), so every client can have a bunch of balls moving on the canvas.
I know I should use socket.io to emit the parameter to the client but i have no clue.
Normally the array is created inside the setup function inside p5...so how could socket do that?
Question #2:
How could the client send the mouseX and mouseY to the server? And then how could the server send back others' mouseX and mouseY to every client?
I try to make p5.js into normal js like this:
(function () {
"use strict";
function sketchProc(processing) {
var p=processing,
var ...,
var ...;
function ball(){...}
p.setup=function(){}
p.draw=function(){}
}
var canvas = document.getElementById("canvas1"),
p = new Processing(canvas, sketchProc);
}());
But i don't know if this helps...
The balls should be passed to the client only in the connection event. That's where node's beauty lies, code sharing.
To create a socket server, you can use either node's native Net module or Socket.io
On the server:
var server = net.createServer();
server.listen(PORT, HOST);
server.on('connection', function(socket) {
socket.write({ type: "BallsArray", data: BallsArray });
});
On the client, you use WebSockets with Socket.io:
var client = io.connect('http://localhost:3000');
var BallsArray = null;
client.on('message', function(msg) {
if(msg.type == "BallsArray")
BallsArray = msg.data;
});
I´m going crazy with socket.io!
Documentation is so bad it's simply not true.
I want to send a feedback to specific client over socket.io
My server side looks like this:
app.get('/upload', requiresLogin, function(request, response) {
response.render('upload/index.jade');
io.sockets.on('connection', function (socket) {
console.log('SOCKET ID ' + socket.id);
io.sockets.socket(socket.id).emit('new', 'hello');
});
});
and the client side looks like this:
$(document).ready(function() {
var socket = io.connect('http://localhost:80/socket.io/socket.io.js');
socket.on('new', function (data) {
console.log(socket.id);
console.log(data);
//$('#state').html(data.status);
});
});
but the client does simply nothing. I have tried nearly everything. Can someone tell me what I am doing wrong, please! :(
to send a message to a specific client save every one that connects to the server in an Object.
var socketio = require('socket.io');
var clients = {};
var io = socketio.listen(app);
io.sockets.on('connection', function (socket) {
clients[socket.id] = socket;
});
then you can later do something like this:
var socket = clients[sId];
socket.emit('show', {});
A couple of ways to send feedback to a specific client over socket.io include:
As stated by pkyeck, save all clients to an Object, so you can send to these specific clients later in your route handlers, e.g.:
var sessionsConnections = {};
sio.on('connection', function (socket) {
// do all the session stuff
sessionsConnections[socket.handshake.sessionID] = socket;
});
or, use socket.io's built in support for rooms - subscribe each client to a room on connection and send via this room within route handlers, e.g.:
sio.on('connection', function (socket) {
// do all the session stuff
socket.join(socket.handshake.sessionID);
// socket.io will leave the room upon disconnect
});
app.get('/', function (req, res) {
sio.sockets.in(req.sessionID).send('Man, good to see you back!');
});
Acknowledgement:
http://www.danielbaulig.de/socket-ioexpress/#comment-1158
Note that both these example solutions assume that socket.io and express have been configured to use the same session store and hence refer to the same session objects. See the links above and below for more details on achieving this:
https://github.com/LearnBoost/socket.io/wiki/Authorizing
2 things
1) You should really place your io.sockets.on(..) outside your app/update route to prevent adding multiple listeners for clients.
2) io.sockets.socket(id); should not be used, it should have been socket.emit('new', 'hello')
In socket.io 1.0, this is how it would work. It may work for lower versions, but I cannot guarantee it.
socket.to(socket_id_here).emit('new', 'hello');
This works because socket.io automatically adds a socket to a room with the socket's id on connection.
Also, if you plan to upgrade to version 1.0, there are a lot of changes to the api, so you'll sometimes have to change some code to make it work in 1.0.
The correct way to do this in Socket.io 1.0+ is:
io.to(users_socket_id).emit('new', 'hello');
You can also substitute a room name for 'users_socket_id' to emit to a specific socket.io room.
First of all, you cannot use socket.id on client side.
And then change the line
var socket = io.connect('http://localhost:80/socket.io/socket.io.js');
to
var socket = io.connect('http://localhost:80/');
I believe io.sockets.socket has been removed and has been a problem in Socket.IO (https://github.com/socketio/socket.io/issues/1618).
You can use io.sockets.connected[socket.id] and store the socket.id to reference with the user via username:
var usernames = {};
usernames[username] = socket.id;
// Sending the message
io.sockets.connected[usernames[username]].emit(...);
I don't see it anywhere on the documentation so I can see how this hasn't been answered. Also, if you don't have any reference via usernames, you can instead try:
users[socket.id] = socket.id;
to duplicate the key and value for easy access.
There is also possibly another way by using io.clients as described below, but I haven't used that method.
OTHER SOLUTION: Send message to specific client with socket.io and node.js
Have you tried using?
var socket = io.connect('http://localhost:80/');
i tired with the latest version of node and socket.io
below i am going to post complete code
<ul id="messages"></ul>
<form action="">
<input id="id1" /><button>Send</button>
</form>
<script src="https://cdn.socket.io/socket.io-1.2.0.js"></script>
<script src="http://code.jquery.com/jquery-1.11.1.js"></script>
<script>
var io = io.connect();
$('form').submit(function(){
io.emit('drumevent', $('#id1').val());
$('#id1').val('');
return false;
});
io.on('drumevent', function(msg){
console.log(msg);
$('#messages').append($('<li></li>').text(msg.message+' quantity = '+msg.quantity));
});
</script>
server side code
var usernames = {};io.on('connection', function(socket){usernames["username"] = socket.id;
socket.on('drumevent', function(msg){
var socketId = socket.id;io.to(socketId).emit('drumevent', data);