cls.js

var cls = require('continuation-local-storage')
  , concat = require('concat-stream')
  , http = require('http')

var foo = cls.createNamespace('foo')

http.createServer(foo.bind(function(req, res) {
  req.pipe(concat(done))

  function done() {
    res.write(JSON.stringify(foo.active)) //null
    res.end()
  }
})).listen(6789)