AMQP Connector

Overview

The AMQP connector enables publish/subscribe messaging through RabbitMQ and any AMQP 0.9.1 broker, with exchanges, queues, and routing keys.

Connector Types:

AmqpReader - Consume messages from a queue or exchange binding
AmqpWriter - Publish messages to an exchange with a routing key

AMQP Reader

Consume messages from an existing queue:

{
  "type": "AmqpReader",
  "config": {
    "url": "amqp://guest:guest@localhost:5672/",
    "queue": "sensor_events",
    "autoAck": false,
    "prefetchCount": 10,
    "consumerTag": "meddle-reader"
  }
}

Bind to an Exchange

When queue is empty and exchange is set, the reader declares a temporary exclusive queue and binds it to the exchange using routingKey:

{
  "type": "AmqpReader",
  "config": {
    "url": "amqp://user:password@rabbit.example.com:5672/",
    "exchange": "factory.events",
    "routingKey": "line1.*.temperature",
    "autoAck": true
  }
}

TLS Connection

{
  "type": "AmqpReader",
  "config": {
    "url": "amqps://user:password@rabbit.example.com:5671/",
    "queue": "secure_events",
    "tls": true,
    "autoAck": false
  }
}

AMQP Writer

Publish messages to an exchange:

{
  "type": "AmqpWriter",
  "config": {
    "url": "amqp://guest:guest@localhost:5672/",
    "exchange": "factory.events",
    "routingKey": "line1.temperature",
    "mandatory": false,
    "contentType": "application/json"
  }
}

Publish to Default Exchange (Queue Directly)

Leave exchange empty and use the queue name as the routing key:

{
  "type": "AmqpWriter",
  "config": {
    "url": "amqp://guest:guest@localhost:5672/",
    "exchange": "",
    "routingKey": "sensor_events"
  }
}

Configuration Parameters

url: AMQP connection URI (amqp://user:pass@host:port/vhost or amqps://...)
exchange: Exchange name (empty string targets the default exchange)
queue: Queue name to consume from (Reader only)
routingKey: Routing key or binding pattern
tls: Use TLS for the connection
prefetchCount: (Reader) Max unacknowledged messages on the channel
autoAck: (Reader) Auto-acknowledge messages on delivery
consumerTag: (Reader) Client-supplied consumer identifier
mandatory: (Writer) Return message to publisher if it cannot be routed
contentType: (Writer) MIME type for published messages (default: application/json)

Acknowledgement Modes

autoAck: true - The broker considers messages delivered as soon as they are sent. Faster but messages can be lost on consumer crash.
autoAck: false - Meddle explicitly acks each successful message and nacks on payload errors. Use with prefetchCount to bound in-flight messages.

Routing Key Patterns

Topic exchanges support wildcards in binding keys:

* matches exactly one word: line1.*.temperature
# matches zero or more words: factory.#

MQTT - Lightweight pub/sub alternative
Kafka - High-throughput log-based messaging
NATS - Cloud-native pub/sub alternative