Setting up a nodejs job queue on Heroku with RabbitMQ (and the jackrabbit npm module)

I am trying to set up a Node.js job queue on Heroku. I am using RabbitMQ with the jackrabbit npm module for this task.

After following the example in the repository, I have the following files:

server.js. Node simple web server.
worker.js. Worker.

As I understand it, on Heroku I start a web process and a worker process in the Procfile:

// Procfile
web: node server.js
worker: node worker.js

In the worker.js file, I do the following:

// worker.js
var http = require('http');
var throng = require('throng');
var jackrabbit = require('jackrabbit')
 // want to use "worker: node worker.js" in heroku Procfile
var queue = jackrabbit(process.env.CLOUDAMQP_URL || 'amqp://localhost')

http.globalAgent.maxSockets = Infinity;

var start = function() {
  queue.on('connected', function() {
    queue.create('myJob', { prefetch: 5 }, function() {
        queue.handle('myJob', function(data, ack) {
            console.log(data)
            console.log("Job completed!")
            ack()
        })
    })
  })
}

throng(start, { 
  workers: 1,
  lifetime: Infinity,
  grace: 4000
})

Now I want a situation where I can push data to a job from the web application. So I in a middleware function I have,

// middleware.js
var jackrabbit = require('jackrabbit')
var queue = jackrabbit(process.env.CLOUDAMQP_URL || 'amqp://localhost')

app.get('/example', function(req, res, next) {
   queue.publish('myJob', { data: 'my_data' })
   res.send(200, { data: 'my_data' })
})

On development, I start worker.js and app.js in separate terminal windows. When I call the /example method, I expect to see the worker terminal window show the relevant console logs. However, the request just hangs. The same thing happens on Heroku.

I feel like there is something really fundamental I am missing here in terms of my understanding of jackrabbit and ampq, and how to set up a job queuing system using that.

Any help on this would be greatly appreciated as this is obviously new to me.