Can I broadcast to all WebSocket clients

I'm assuming this isn't possible, but wanted to ask in case it is. If I wa开发者_如何学JAVAnt to provide a status information web page, I want to use WebSockets to push the data from the server to the browser. But my concerns are the effect a large number of browsers will have on the server. Can I broadcast to all clients rather than send discrete messages to each client?

WebSockets uses TCP, which is point to point, and provides no broadcast support.

Not sure how is your client/server setup, but you can always just keep in the server a collection of all connected clients - and then iterate over each one and send the message.

A simple example using Node's Websocket library:

Server code

var WebSocketServer = require('websocket').server;

var clients = [];
var socket = new WebSocketServer({
  httpServer: server,
  autoAcceptConnections: false
});

socket.on('request', function(request) {
  var connection = request.accept('any-protocol', request.origin);
  clients.push(connection);

  connection.on('message', function(message) {
    //broadcast the message to all the clients
    clients.forEach(function(client) {
      client.send(message.utf8Data);
    });
  });
});

As noted in other answers, WebSockets don't support multicast, but it looks like the 'ws' module maintains a list of connected clients for you, so it's pretty easy to iterate through them. From the docs:

const WebSocketServer = require('ws').Server;
const wss = new WebSocketServer({ port: 8080 });

wss.broadcast = function(data) {
  wss.clients.forEach(client => client.send(data));
};

Yes, it is possible to broadcast messages to multiple clients.

In Java,

  @OnMessage
  public void onMessage(String m, Session s) throws IOException {
  for (Session session : s.getOpenSessions()) {
    session.getBasicRemote().sendText(m);
   }
}

and here it is explained. https://blogs.oracle.com/PavelBucek/entry/optimized_websocket_broadcast.

It depends on the server-side really. Here's an example of how it's done using Tomcat7:

Tomcat 7 Chat Websockets Servlet Example

and an explanation of the how it's constructed here.

Yes you can and there are many socket servers out there written in various scripting languages that are doing it.

The Microsoft.Web.WebSockets namespace has a WebSocketCollection with Broadcast capability. Look for the assembly in Nuget. The name is Microsoft.WebSockets.