Proxy twitter stream via socket.io

Question

I've got socket.io set up with node.js. My scenario is a user/client supplies a twitter screen_name to follow, and then I need to subscribe to that twitter stream using the supplied screen_name (for some asinine reason the API requires a user_id instead of a screen_name).

I've run into a sequence problem where I have to subscribe to the stream before I know the screen_name (and subsequently the user_id):

var tweetStream;

io.sockets.on('connection', function connect( socket )
{
  socket.on('subscribe', function(data)
  {
    twitter.get(
      'statuses/user_timeline',
      { "screen_name": data.screen_name },
      function getTweets( err , tweets )
      {
        // …
        // var user_id …

        tweetStream = twitter.stream('statuses/filter', { "follow": user_id });
        console.log('\n','tweetStream: ', tweetStream, '\n');

        tweetStream.on('tweet', function onTweet(tweet)
        {
          console.log( '\ntweetStream -> new tweet: ', tweet, '\n' );
          io.sockets.in( data.screen_name ).emit('tweets', tweet );
        });
      }
    );
  });
}

The above does not subscribe to the tweetstream and does not produce an error. If I move the tweetStream code outside of socket.io and hard-code a user_id (because it's otherwise not available), it works:

var tweetStream;

io.sockets.on('connection', function connect( socket )
{
  …
}

tweetStream = twitter.stream('statuses/filter', { "follow": 6253282 });
console.log('\n','tweetStream: ', tweetStream, '\n');

tweetStream.on('tweet', function onTweet(tweet)
{
  console.log( '\ntweetStream -> new tweet: ', tweet, '\n' )
  io.sockets.in( tweet.user.screen_name ).emit('tweets', data );
});

EDIT

The tweetStream objects in both cases are identical (compared via FileMerge).

Here's a Gist with the complete code.

Answer 1

The problem was that the twitter instance needs to be instantiated inside the socket.on('subscribe') callback:

// …
var io      = require('socket.io').listen(server);
var Twit    = require('twit');

io.sockets.on('connection', function connect( socket )
{
    //…
    socket.on('subscribe', function subscribe( data )
    {
        var twitter = new Twit({ … });
        // …
    });
    //…
});