cls.js

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

var foo = cls.createNamespace('foo')

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

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