example of using express middleware to gzip xml files

express.js

var express = require('express');
var connect = require('connect');
var zlib = require('zlib');
var fs = require('fs');
var app = express();

var compressOptions = {
  filter: function(req, res) {
    return /json|text|xml|javascript/.test(res.getHeader('Content-Type'))
  }
};

app.use(express.compress(compressOptions));
app.use(express.static(__dirname + '/public'));

app.get('/', function(req, res){
  res.sendfile('./public/data.xml');
});

app.listen(8000);