send message to a specific connected client

[pacmac]

Is there any way of initiating a message to a connected client as opposed to replying to a message from a client ?

[fecaleagle]

If you keep track of clients on connect, it's very easily done. This is more or less a duplicate of: #81

I took a similar approach to @michael and did something like this on connect, dirtying the ws object with an id...

var id = 0;
var lookup = {};

wss.on('connection', function(ws) {
  ws.id = id++;
  lookup[ws.id] = ws;

  [...]
}

if you want to send a message to the client with id == 0, you'd just call...

lookup[0].send('message');

There's probably a better way to do this, but it's working fine for me.

[bryku]

If you keep track of clients on connect, it's very easily done. This is more or less a duplicate of: #81

I took a similar approach to @michael and did something like this on connect, dirtying the ws object with an id...

var id = 0;
var lookup = {};

wss.on('connection', function(ws) {
  ws.id = id++;
  lookup[ws.id] = ws;

  [...]
}

if you want to send a message to the client with id == 0, you'd just call...

lookup[0].send('message');

There's probably a better way to do this, but it's working fine for me.

Can you also send something to everyone without looping through the lookup?

[WiktorLigeza]

Hi, i have just used this method but lookup[i].send(msg) isn't sending anything in this configuration, it does work when i broadcast to all, like so:
wsServer.clients.forEach(function (client) { client.send(msg); });
, or when i send raw msg just after i establish connection like:
wsServer.on('connection', function (socket) { socket.send("Hello!") ...

basically what the following code does is: Client with tag connects to a server and is being remembered, client without tag just sends information with a specific destination which is being represented by that tag, so the role of the server is just to forward this info to a specific client

`

    var id = 0;
    var lookup = {};
    var clients_tag = [];
    
    Object.size = function(obj) {
      var size = 0,
        key;
      for (key in obj) {
        if (obj.hasOwnProperty(key)) size++;
      }
      return size;
    };
    
    wsServer.on('connection', function (socket) {
        socket.on('message', function (msg) {
            if (msg.slice(0, 3) == "TAG"){
              socket.id = id++;
              lookup[socket.id] = socket;
              clients_tag[socket.id] = msg.slice(3);
              console.log(msg.slice(3) + " - just connected, with id: "+ socket.id);
              
            }
           else{
             const msg_obj = JSON.parse(msg);
             console.log("from "+  msg_obj.user + " to " + msg_obj.device_tag + " || color value: " +  msg_obj.color);
             
             for (var i = 0; i < Object.size(lookup); i++){ 
                 if(clients_tag[i] == msg_obj.device_tag){
                   console.log("sending to client with id: ", lookup[i].id);
                   lookup[i].send(msg);
                 }
             }
           }
            
            // wsServer.clients.forEach(function (client) {
            //     client.send(msg);
            // });
        });
    });

`

output after connecting 3 clients, 2 are listening 1 is sending - and it works fine but nothing is being sent to a specific client:
2137 - just connected, with id: 0
2134 - just connected, with id: 1
from John to 2137 || color value: #b18181
sending to a client with id: 0

[netizen-ais]

@WiktorLigeza I think you're mixing id/tag. This is not an issue in this library, but your code. Try SO or google for help

[webcoderph]

If you keep track of clients on connect, it's very easily done. This is more or less a duplicate of: #81

I took a similar approach to @michael and did something like this on connect, dirtying the ws object with an id...

var id = 0;
var lookup = {};

wss.on('connection', function(ws) {
  ws.id = id++;
  lookup[ws.id] = ws;

  [...]
}

if you want to send a message to the client with id == 0, you'd just call...

lookup[0].send('message');

There's probably a better way to do this, but it's working fine for me.
@fecaleagle
how would you manage that array if the socket is disconnected? I mean, what is the best way to handle that kind of situation? Thanks