How to send a message to a particular client with socket.io

I'm starting with socket.io + node.js, I know how to send a message locally and to broadcast socket.broadcast.emit() function:- all the connected clients receive the same message.

Now, I would like to know how to send a private message to a particular client, I mean one socket for a private chat between 2 person (Client-To-Client stream). Thanks.

Solution 1:

You can use socket.io rooms. From the client side emit an event ("join" in this case, can be anything) with any unique identifier (email, id).

Client Side:

var socket = io.connect('http://localhost');
socket.emit('join', {email: [email protected]});

Now, from the server side use that information to create an unique room for that user

Server Side:

var io = require('socket.io').listen(80);

io.sockets.on('connection', function (socket) {
  socket.on('join', function (data) {
    socket.join(data.email); // We are using room of socket io
  });
});

So, now every user has joined a room named after user's email. So if you want to send a specific user a message you just have to

Server Side:

io.sockets.in('[email protected]').emit('new_msg', {msg: 'hello'});

The last thing left to do on the client side is listen to the "new_msg" event.

Client Side:

socket.on("new_msg", function(data) {
    alert(data.msg);
}

I hope you get the idea.

Solution 2:

When a user connects, it should send a message to the server with a username which has to be unique, like an email.

A pair of username and socket should be stored in an object like this:

var users = {
    '[email protected]': [socket object],
    '[email protected]': [socket object],
    '[email protected]': [socket object]
}

On the client, emit an object to the server with the following data:

{
    to:[the other receiver's username as a string],
    from:[the person who sent the message as string],
    message:[the message to be sent as string]
}

On the server, listen for messages. When a message is received, emit the data to the receiver.

users[data.to].emit('receivedMessage', data)

On the client, listen for emits from the server called 'receivedMessage', and by reading the data you can handle who it came from and the message that was sent.

Solution 3:

SURE: Simply,

This is what you need :

io.to(socket.id).emit("event", data);

whenever a user joined to the server, socket details will be generated including ID. This is the ID really helps to send a message to particular people.

first we need to store all the socket.ids in array,

var people={};

people[name] =  socket.id;

here name is the receiver name. Example:

people["ccccc"]=2387423cjhgfwerwer23;

So, now we can get that socket.id with the receiver name whenever we are sending message:

for this we need to know the receivername. You need to emit receiver name to the server.

final thing is:

 socket.on('chat message', function(data){
io.to(people[data.receiver]).emit('chat message', data.msg);
});

Hope this works well for you.

Good Luck!!

Solution 4:

You can refer to socket.io rooms. When you handshaked socket - you can join him to named room, for instance "user.#{userid}".

After that, you can send private message to any client by convenient name, for instance:

io.sockets.in('user.125').emit('new_message', {text: "Hello world"})

In operation above we send "new_message" to user "125".

thanks.