RabbitMQ

AMQP messaging solution ideal for IoT and client / server use cases

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.

Additionally, the page highlights the usage of Joule to consume events via RabbitMQ messaging subscriptions.

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

Examples & DSL attributes

This example shows how to configure a RabbitMQ consumer that subscribes to specific event types using routing keys with a topic exchange.

The consumer listens for events related to quotes for specific stocks (IBM, MSFT and GOOG) from the marketQuotes exchange.

The events are deserialised from a StreamEvent JSON object into a Joule StreamEvent object using a custom parser.

rabbitConsumer:
  host: localhost
  exchange:
    name: marketQuotes
    type: TOPIC
  
  routing:
    keys:
      - NASDAQ.IBM
      - NASDAQ.MSFT
      - NASDAQ.GOOG
  
  deserializer:
    parser: 
      com.fractalworks.examples.banking.data.QuoteToStreamEventParser

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
prefetchCount	QoS -maximum number of messages that the server will deliver, 0 if unlimited	Integer Default: 1
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 sttributes section
routing	Routing configuration	See routing attributes section
deserializer	Deserialisation configuration	See Deserialisation documentation

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

rabbitConsumer:
    ...
    exchange:
        name: marketQuotes
        type: DIRECT

Routing attributes schema

Attribute	Description	Data Type	Required
keys	Consumers can selectively consume events sent to a topic exchange by specifying one or more words delimited by dots. Learn more about how to apply it here. Valid key format examples: 'nasdaq.ibm', 'dept.inventory.bolts'. There are two important special cases to define keys: *(star) can be substituted for exactly one word #(hash) can be substituted for zero or more words	String Default: All Constraints: Any number of dot separated words to a limit of 255 bytes

Routing example

This example will subscribe to all events that match the first component of the key 'NASDAQ'

rabbitConsumer:
    ...
    routing:
        keys:
          - NASDAQ.#

Additional resources

Further AMQP resources can be found on the following links:

• Official RabbitMQ documentation
• CloudAMQP documentation