AMQP (Advanced Message Queuing Protocol)

The library provides support for both direct exchanges and topic exchanges.

> _NOTE:_ Check README.md for transport-agnostic library documentation.

Publishers

Use AbstractAmqpQueuePublisher to implement direct exchange and AbstractAmqpTopicPublisher for topic exchange.

See test publisher for an example of implementation.

Consumers

Use AbstractAmqpQueueConsumer to implement direct exchange and AbstractAmqpTopicConsumer for topic exchange.

See test consumer for an example of implementation.

Automatic Reconnects

message-queue-toolkit automatically reestablishes connections for all publishers and consumers via AmqpConnectionManager mechanism.

Example:

``ts
export const TEST_AMQP_CONFIG: AmqpConfig = {
vhost: '',
hostname: 'localhost',
username: 'guest',
password: 'guest',
port: 5672,
useTls: false,
}

const amqpConnectionManager = new AmqpConnectionManager(config, logger)
await amqpConnectionManager.init()

const publisher = new TestAmqpPublisher(
{ amqpConnectionManager },
{
// other amqp options
},
)
await publisher.init()

const consumer = new TestAmqpConsumer(
{ amqpConnectionManager },
{
// other amqp options
},
)
await consumer.start()

// break connection, to simulate unexpected disconnection in production
await (await amqpConnectionManager.getConnection()).close()

const message = {
// some test message
}

// This will fail, but will trigger reconnection within amqpConnectionManager
publisher.publish(message)

// eventually connection is reestablished and propagated across all the AMQP services that use same amqpConnectionManager

// This will succeed and consumer, which also received new connection, will be able to consume it
publisher.publish(message)
`

Lazy instantiation

By default message-queue-toolkit/amqp will lazily instantiate publishers before the publish in case they weren't instantiated before. This may result in system not failing fast when connection to AMQP cannot be established, as instantiation happens asynchronously. In case that is an undesirable behaviour, you can set parameter isLazyInitEnabled to false either directly for a publisher, or as one of the newPublisherOptions parameters for the AmqpQueuePublisherManager.

In case when lazy instantiation is disabled, publishers should be initialized explicitly by using an async AmqpQueuePublisherManager.initRegisteredPublishers() method. It also has an optional publishers?: string[]` argument, which can be used to only initialize some specific publishers.