Socket.io Rooms in a Hostile Network Environment?

Question

I have a very frustrating problem with a client's network environment, and I'm hoping someone can lend a hand in helping me figure this out...

They have an app that for now is written entirely inside of VBA for Excel. (No laughing.)

Part of my helping them improve their product and user experience involved converting their UI from VBA form elements to a single WebBrowser element that houses a rich web app which communicates between Excel and their servers. It does this primarily via a socket.io server/connection.

When the user logs in, a connection is made to a room on the socket server.

Initial "owner" called:

socket.on('create', function (roomName, userName) {
    socket.username = userName;
    socket.join(roomName);
});

Followup "participant" called:

socket.on('adduser', function (userName, roomName){

    socket.username = userName;
    socket.join(roomName);
    servletparam = roomName;
    var request = require('request');

    request(bserURL + servletparam, function (error, response, body) {
        io.sockets.to(roomName).emit('messages', body);
    });

    servletparam = roomName + '|' +  userName;
    request( baseURL + servletparam, function (error, response, body) {
        io.sockets.to(roomName).emit('participantList', body);
    });
});

This all worked beautifully well until we got to the point where their VBA code would lock everything up causing the socket connection to get lost. When the client surfaces form it's forced VBA induced pause (that lasts anywhere from 20 seconds to 3 minutes), I try to join the room again by passing an onclick to an HTML element that triggers a script to rejoin. Oddly, that doesn't work. However if I wait a few seconds and click the object by hand, it does rejoin the room. Yes, the click is getting received from the Excel file... we see the message to the socket server, but it doesn't allow that call to rejoin the room.

Here's what makes this really hard to debug. There's no ability to see a console in VBA's WebBrowser object, so I use weinre as a remote debugger, but a) it seems to not output logs and errors to the console unless I'm triggering them to happen in the console, and b) it loses its connection when socket.io does, and I'm dead in the water.

Now, for completeness, if I remove the .join() calls and the .to() calls, it all works like we'd expect it to minus all messages being written into a big non-private room. So it's an issue with rejoining rooms.

As a long-time user of StackOverflow, I know that a long question with very little code is frowned upon, but there is absolutely nothing special about this setup (which is likely part of the problem). It's just simple emits and broadcasts (from the client). I'm happy to fill anything in based on followup questions.

score 3 · Accepted Answer · answered Sep 30 '14 at 17:25

To anyone that might run across this in the future...

The answer is to manage your room reconnection on the server side of things. If your client can't make reliable connections, or is getting disconnected a lot, the trick it to keep track of the rooms on the server side and join them when they do a connect.

The other piece of this that was a stumper was that the chat server and the web UI weren't on the same domain, so I couldn't share cookies to know who was connecting. In their case there wasn't a need to have them hosted in two different places, so I merged them, had Express serve the UI, and then when the client surfaced after a forced disconnect, I'd look at their user ID cookie, match them to the rooms they were in that I kept track of on the server, and rejoined them.

Socket.io Rooms in a Hostile Network Environment?

1 Answers1