@subfuzion/queue

This is a simple queue package intended for a demo application used for educational purposes.

It provides a Producer class for enqueueing messages and a Consumer class for dequeueing them.

The queue is implemented using Redis and this package provides a trivial wrapper over the ioredis client for Node. The wrapper essentially provides a minimal facade for using a simple queue, and also serves to illustrate how to use and test basic Redis operations using ES2017 async/await support now available natively in Node.js.

This package is inspired by the existing Docker Example Voting App. The existing app is an excellent example of a real world polyglot application, demonstrating containerized processes created from a number of different programming languages. This package is intended to support a simpler version of the voting application that only uses Node.js and modern JavaScript that some developers may find a bit easier to follow while trying to understand how the application actually works.

Testing

Redis needs to be available before running tests. The tests default to port 6379 on localhost, but host and port can be overridden by setting HOST and PORT environment variables.

If you have Docker installed, you can easily start Redis with the default values by running the following command:

$ docker run -d -p 6379:6379 --name queue redis

This will run a redis container named queue in the background with port 6379 on your system mapped to the exposed port 6379 in the container.

To run the tests, enter the following:

$ npm test

When finished, you can remove the running container from your system with:

$ docker rm -f queue

Using @subfuzion/queue

Add the dependency to your package:

npm:

$ npm install @subfuzion/queue

yarn:

$ yarn add @subfuzion/queue

Enqueueing Messages

var p = new Producer(topic [, config])
await p.send(message)
// when finished with the producer:
await p.quit()

where topic should be the queue topic and config is an optional object that can have host and port values.

Dequeueing Messages

var c = new Consumer(topic [, config])
let message = await c.receive(topic)
// when finished with the consumer: 
await c.quit()

where topic and config are the same as described previously.

Note that the receive method blocks until there is a message ready to be retrieved from the queue. The method will return null if the connection is closed (by calling quit) while it is waiting.

Closing Connections

You should always call quit on producers and consumers to ensure connections are gracefully closed on both the client and server sides.