Node.js oauth twitter authentication

console.log('npm install express oauth');

var express = require('express'), 
    app = express.createServer(), /*from w w w.  j av a  2s .  c o  m*/
    oauth = require('oauth'), 
    fs = require('fs');

var auth = {
  key : fs.readFileSync(__dirname + '/twitterConsumerKey'),
  secret : fs.readFileSync(__dirname + '/twitterConsumerSecret'),
  callback : "http://localhost/sessions/callback"
};

function consumer() {
  return new oauth.OAuth("https://twitter.com/oauth/request_token",
      "https://twitter.com/oauth/access_token", auth.key, auth.secret,
      "1.0A", auth.callback, "HMAC-SHA1");
}

app.get(
    '/',
    function(req, res) {
      res.send('<a href="/sessions/connect"><img src="http://si0.twimg.com/images/dev/buttons/sign-in-with-twitter-l.png"/></a>');
    });

app.get('/sessions/connect', function(req, res) {
  consumer().getOAuthRequestToken(
      function(err, oauthToken, oauthTokenSecret, results) {
        if (err)
          throw err;
        auth.oauthRequestToken = oauthToken;
        auth.oauthRequestTokenSecret = oauthTokenSecret;
        res.redirect("https://twitter.com/oauth/authorize?oauth_token="
            + auth.oauthRequestToken);
      });
});

app.get('/sessions/callback', function(req, res) {
  consumer().getOAuthAccessToken(
      auth.oauthRequestToken,
      auth.oauthRequestTokenSecret,
      req.query.oauth_verifier,
      function(err, oauthAccessToken, oauthAccessTokenSecret, results) {
        if (err)
          throw err;
        // Right here is where we would write out some nice user stuff
        consumer().get(
            "http://twitter.com/account/verify_credentials.json",
            oauthAccessToken,
            oauthAccessTokenSecret,
            function(err, data, response) {
              if (err)
                throw err;
              data = JSON.parse(data);
              console.dir(data);
              res.send('You are signed in: ' + data.screen_name
                  + '<br/><br>' + JSON.stringify(data));
            });
      });
});

app.listen(80);