code: function ServerClientStream(app){
      var StreamHandler;
      app.use(function(req, res, next){
        if(req.originalUrl == '/promise-pipe-connector' && req.method=='POST'){
          var message = req.body;
          message._response = res;
          StreamHandler(message)
        } else {
          return next();
        }
      });
      return {
        send: function(message){
          if(!message._response) throw Error("no response defined");
          var res = message._response;
          message._response = undefined;
          res.json(message);
        },
        listen: function(handler){
          StreamHandler = handler;
        }
      }
    }
docs: express app highly experimental