RabbitMQ

RabbitMQ is lightweight and easy to deploy messaging platform for event-based data integration

Overview

RabbitMQ is a lightweight and easy-to-deploy messaging platform that supports multiple messaging protocols. It can be configured in distributed and federated setups to meet high-scale and high-availability requirements.

Joule enables publishing to RabbitMQ queues, exchanges and topics, providing flexible event-driven architectures.

This page covers how to configure RabbitMQ publishers within Joule, including queue-based eventing, work queues for task distribution, publish / subscribe models and routing with dynamic keys.

The examples demonstrate how to serialise events into JSON, configure exchanges and use routing keys for targeted message delivery.

Additionally, it provides configuration details for common patterns like worker queues and topic-based exchanges, offering scalability and efficiency in event processing.

Client library: com.rabbitmq:amqp-client:5.16.0

Examples & DSL attributes

This example configures the RabbitMQ Publisher to send StreamEvents as JSON-formatted messages to a queue named quotes_queue.

Here's a breakdown:

1. queue The events will be published to the quotes_queue, a named queue in RabbitMQ.

2. serializer The events are serialized using the jsonFormatter with UTF-8 encoding, ensuring the data is formatted as JSON.

This setup sends JSON-encoded events to the quotes_queue in RabbitMQ, with the message content encoded in UTF-8.

rabbitPublisher:
  queue: quotes_queue
  
  serializer:
    formatter:
      jsonFormatter:
        encoding: UTF-8

Attributes schema

Attribute	Description	Data Type	Required
host	RabbitMQ server hostname or Ip address	String Default: localhost
port	RabbitMQ server port, must be greater than 0.	Integer Default: 5672
username	User name	String Default: guest
password	password	String Default: guest
virtualHost	Creates a logical group of connections, exchanges, queues, bindings, user permissions, etc. within an instance. See vhost documentation for further information	String Default: /
autoAck	Flag to consider if server should message acknowledged once messages have been delivered. False will provide explicit message acknowledgment.	Boolean Default: true
global	QoS - true if the settings should be applied to the entire channel rather than each consumer	Boolean Default: true
durable	Set a durable queue (queue will survive a server restart)	Boolean Default: true
autoDelete	Server deletes queue when not in use	Boolean Default: true
exclusive	Exclusive queue to this connection	Boolean Default: false
arguments	Additional queue properties	Map<String, Object> Default: null
exchange	Exchange configuration	See Exchange attributes section
routing	Routing configuration	See Routing attributes section
serializer	Serialisation configuration	See Serialization attributes section

Exchange attributes schema

Attribute	Description	Data Type	Required
name	Name of exchange	String
type	In RabbitMQ, messages are published to an exchange and, depending on the type of exchange, the message gets routed to one or more queues	TOPIC, DIRECT, FANOUT, HEADERS Default: TOPIC
arguments	Additional binding properties	Map<String, Object> Default: null

Exchange example

This example configures the RabbitMQ Publisher to send events to an exchange instead of a queue:

1. exchange The events are published to an exchange named marketQuotes.

   1. type The exchange type is set to TOPIC, meaning events can be routed based on routing keys that include wildcards. This allows consumers to subscribe to specific types of messages using patterns like market.IBM or market.*.

This setup sends events to the marketQuotes topic exchange, enabling more flexible routing of messages based on the routing keys used by consumers.

rabbitPublisher:
    ...

    exchange:
        name: marketQuotes
        type: TOPIC

Routing attributes schema

Attribute	Description	Data Type	Required
event fields	List of event fields to create dynamic routing keys	String Default: None

Routing example

In this example, the RabbitMQ Publisher is configured to dynamically create a routing key based on the market and symbol fields from the StreamEvent:

1. routing The routing key is constructed using the values of the market and symbol fields in the event. For example, if the market is nasdaq and the symbol is IBM, the routing key nasdaq.IBM will be created.

This enables fine-grained control over which events are routed to specific consumers, as they can subscribe to events using specific routing keys like nasdaq.IBM or nasdaq.*.

rabbitPublisher:
  ...

    routing:
        event fields:
          - market
          - symbol

Serialisation attributes schema

Attribute	Description	Data Type	Required
transform	User provided implementation that transforms the StreamEvent in to a domain class. The resulting domain class must implement serialisable interface	Implementation of StreamEventParser
formatter	If a custom transformer has not been provided the for formatter setting will be applied to the processed StreamEvent object	Default: jsonFormatter
compressed	Not implemented	Boolean Default: false

Serialiser example

This example demonstrates how to configure the serialiser for the RabbitMQ Publisher:

1. serializer The jsonFormatter is used to serialise the events.

   1. encoding The events are encoded in UTF-8, ensuring that the message content is in a standard JSON format that can be easily consumed by downstream applications.

This setup serialises the events into JSON format with UTF-8 encoding before publishing them to RabbitMQ.

rabbitPublisher:
  ...

  serializer:
    formatter:
      jsonFormatter:
        encoding: UTF-8

Additional resources

• Offical RabbitMQ documentation
• CloudAMQP documentation