# graphql-amqp-subscriptions

This package implements the PubSubEngine Interface from the [graphql-subscriptions](https://github.com/apollographql/graphql-subscriptions) package.
It allows you to connect your subscriptions manager to a AMQP PubSub mechanism.

This package is influenced by [graphql-redis-subscriptions](https://github.com/davidyaha/graphql-redis-subscriptions) and [graphql-rabbitmq-subscriptions](https://github.com/cdmbase/graphql-rabbitmq-subscriptions).

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## graphql-subscriptions@2

If you are using `graphql-subscriptions@2.x` please use `graphql-amqp-subscriptions@2`.

## Basic usage

```javascript
import { AMQPPubSub } from 'graphql-amqp-subscriptions';
import amqp from 'amqplib';

amqp.connect('amqp://guest:guest@localhost:5672?heartbeat=30')
.then(conn => {
  const pubsub = new AMQPPubSub({
    connection: conn
    /* exchange: {
       name: 'exchange',
       type: 'topic',
       options: {
         durable: false,
         autoDelete: true
       }
     },
     queue: {
       name: 'queue'
       options: {
         exclusive: true,
         durable: true,
         autoDelete: true
       },
       unbindOnDispose: false;
       deleteOnDispose: false;
     } */
  });
  // Use the pubsub instance from here on
})
.catch(err => {
  console.error(err);
});
```

## Benefits

- Reusing existing [amqplib](https://github.com/squaremo/amqp.node) Connection
- Reusing channels (one for subscriptions, one for publishing)
- Performance/Ressource-usage benefits on AMQP (RabbitMQ) because of the aforementioned reasons [more info](https://www.cloudamqp.com/blog/2018-01-19-part4-rabbitmq-13-common-errors.html)
- Using Topic Exchange (e.g. you publish to `agreements.eu.berlin.headstore` and subscribe to `agreements.eu.#`) [more info](https://www.cloudamqp.com/blog/2015-09-03-part4-rabbitmq-for-beginners-exchanges-routing-keys-bindings.html)

## Debug

This package uses Debug.
To show the logs run your app with the environment variable DEBUG="AMQPPubSub"

## Tests

You'll need to have a local AMPQ instance such as RabbitMQ running to run tests.

If you have [Docker](https://www.docker.com/), you can run:

```bash
docker run --hostname my-rabbit -p 5672:5672 rabbitmq:3
```

Then

```bash
npm test
```