Sending a message to a client via its socket.id

Question

I can only seem emit messages to users when their socket id has been directly stored within the io.sockets.on(\'connect\') function. I don\'t know why it doesn\'t work when

Answer 1

I can see that this post is generating quite a lot of interest... so i'm going to post the code I used to implement this:

Notes

I have used Redis as the session storage. The session is initially setup during the login page via a HTTP request containing the users details, if these details are valid (Checked against a MongoDB document)... then the session is created.

Server Side Code Creation and Removal of Session / Socket

//Auth the user
io.set('authorization', function (data, accept) {
  // check if there's a cookie header
  if (data.headers.cookie) {
    data.cookie = parseCookie(data.headers.cookie);
    data.sessionID = data.cookie['express.sid'];

    //Save the session store to the data object
    data.sessionStore = sessionStore;

    sessionStore.get(data.sessionID, function(err, session){
      if(err) throw err;

      if(!session)
      {
        console.error("Error whilst authorizing websocket handshake");
        accept('Error', false);
      }
      else
      {
        console.log("AUTH USERNAME: " + session.username);
        if(session.username){
          data.session = new Session(data, session);
          accept(null, true);
        }else {
          accept('Invalid User', false);
        }
      }
    })
  } else {
    console.error("No cookie was found whilst authorizing websocket handshake");
    return accept('No cookie transmitted.', false);
  }
});

/** A new socket connection has been accepted */
io.sockets.on('connection', function (socket)
{    
  var hs = socket.handshake;
  if(hs.session)
  {
    if(hs.session.username)
    {
        clients[socket.id] = socket; // add the client data to the hash
        validUsers[hs.session.username] = socket.id; // connected user with its socket.id
    }
  }


  socket.on('disconnect', function()
  {
    delete browsing[hs.session.username]; //Remove the client from the browsing hash
    delete clients[socket.id];         // remove the client from the array
    delete validUsers[hs.session.username]; // remove connected user & socket.id
  })
....
}

Server Side Selective Message Sending

This code allows me to send a message to team members of a project. A team of users won't receive messages from a separate team of users..

for(var i = 0; i < project.team.length; i++)
{
  if(validUsers[project.team[i].username])
  {
    if(clients[validUsers[project.team[i].username]])
    {
      projects.update({"_id" : projectId},
        {"$pull" :
          {"stories" : {"_id" :  storyId}}
        }
      );                
      clients[validUsers[project.team[i].username]].emit('delete-story', storyId); 
    }
    else
    {
      console.error("Project team member not found");
    }
  }
}