amqp-wrapper

amqp-wrapper

Simple consuming and publishing from/to a RabbitMQ broker.

Declarative API to consume from a rabbitMQ queue and to perform publish operations.

• Auto queue declaration & binding
• Dead lettering support
• Easy publishing
• Simple promise based API

Example usage

const AMQP = require('amqp-wrapper');

var config = {
  url: process.env.AMQP_URL,
  exchange: process.env.AMQP_EXCHANGE,
  queue: {
    name: process.env.AMQP_CONSUME,
    routingKey: process.env.AMQP_ROUTING_KEY, // If supplied, queue is bound to
    // this key (or keys) on the exchange. NB Can be an array of strings or just
    // a string.
    options: {/* ... */} // Advanced: options passed to ch.assertQueue() in wrapped `amqplib`.
  },
  // Set the QOS/prefetch (defaults to 1)
  prefetch: 100
};

const amqp = new AMQP(config);

async function main () {
  // Must call this before you consume/publish/etc...
  await amqp.connect();

  // Consuming
  var handleMessage = function(message, callback) {
    //... Do things
    callback();
  };
  // You must call:
  callback(err, requeue)
  // in your handleMessage. If `err` !== `null` then the message will be `nack`ed.
  // Requeueing will be requeue iff `requeue` is `true`.
  // If `err` is `null` then the message is `ack`ed.
  // If an exception occurs in handleMessage, then the message is `nack`ed and not requeued.

  // Start consuming:
  amqp.consume(handleMessage);

  // Publishing to arbitrary routing key.
  await amqp.publish(routingKey, payload, options);
}

If payload is an object, it will be turned into JSON.

Details

• You can specify a queue which will be declared (made to exist). This will be the queue from which you will consume.
• If you specify a routing key for the queue, then a binding will be set up (I.e. a mapping that tells AMQP to route message with that routing key to that queue on the exchange you have specified).
• Any options you specify at the per-queue level are passed directly through to ch.assertQueue in the underlying library. If you want to set up dead lettering, for example, then pass the deadLetterExchange option which will cause the queue to be declared with that dead letter exchange.
• deadLetterExchange and deadLetterRoutingKey are special options, in that as well as being passed through to ch.assertQueue() to ensure the dead lettering behaviour occurs, a queue will be declared of the same name with the -dead-letter suffix, with a binding declared on the dead letter exchange for the dead letter routing key. This means that when a message is dead lettered on that queue it will have somewhere to go without you having to set up a dead lettering queue manually.

Thanks to

This is a wrapper to https://github.com/squaremo/amqp.node (amqplib).

Tests

Start a rabbit server, preferably a 'throw away' one with fresh state. You can do this like so if you have docker:

docker run -d --rm -p 5672:5672 rabbitmq

Wait for it to finish starting up, then:

npm test

Note that tests/config.js currently assumes you are using boot2docker (on a Mac) so you may need to hack that stuff (or it may just work as it should just use localhost if it's not there... unproven though.)

API

AMQPWrapper

Class to contain an instantiated connection/channel to AMQP with a given config.

Kind: global class

• AMQPWrapper
  • new AMQPWrapper(config)
  • .connect() ⇒ Promise
  • .close() ⇒ Promise
  • .publish(routingKey, message, options) ⇒ Promise
  • .consume(handleMessage, options) ⇒ Promise

new AMQPWrapper(config)

Instantiate an AMQP wrapper with a given config.

Param	Type
config	object
config.url	string
config.exchange	string
config.queue	object
config.queue.name	string
config.queue.routingKey	Array.<string> | string
config.queue.options	object

amqpWrapper.connect() ⇒ Promise

Connects, establishes a channel, sets up exchange/queues/bindings/dead lettering.

Kind: instance method of AMQPWrapper

amqpWrapper.close() ⇒ Promise

Closes connection.

Kind: instance method of AMQPWrapper

amqpWrapper.publish(routingKey, message, options) ⇒ Promise

Publish a message to the given routing key, with given options.

Kind: instance method of AMQPWrapper

Param	Type
routingKey	string
message	object | string
options	object

amqpWrapper.consume(handleMessage, options) ⇒ Promise

handleMessage() is expected to be of the form: handleMessage(parsedMessage, callback). If callback is called with a non-null error, then the message will be nacked. You can call it like: callback(err, requeue) in order to instruct rabbit whether to requeue the message (or discard/dead letter).

If not given, requeue is assumed to be false.

cf http://squaremo.github.io/amqp.node/doc/channel_api.html#toc_34

Kind: instance method of AMQPWrapper

Param	Type
handleMessage	function
options	object

License

(The MIT License)

Copyright (c) 2014 Noble Samurai

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.