loopback-component-mq

Loopback Component for working with a Message Queue

Installation

Install in you loopback project:

npm install --save loopback-component-mq

Create a component-config.json file in your server folder (if you don't already have one)
Configure options inside component-config.json. (see configuration section)

{
  "loopback-component-mq": {
    "options": {
      "dataSource": "rabbit",
      "acls": [{
        "accessType": "*",
        "principalType": "ROLE",
        "principalId": "$unauthenticated",
        "permission": "DENY"
      }]
    },
    "topology": {
      "my-event-queue": {
        "consumer": {
          "model": "Event",
          "method": "consumeEventMessage"
        },
        "producer": {
          "model": "Event",
          "method": "produceEventMessage"
        }
      }
    }
  }
}

Configure the Rabbit Data Source inside datasources.json:

{
  "rabbit": {
    "name": "rabbit",
    "connector": "transient",
    "options": {
      "protocol": "amqp",
      "username": "guest",
      "password": "guest",
      "hostname": "localhost",
      "port": "5672",
      "restPort": "15672",
      "vhost": "/",
      "sslKey": ""
    }
  }
}

Configuration

The configuration of this component happens in component-config.json.

The 2 top-level keys are options and topology which are both objects.

Options

The options object has 2 keys:

dataSource (String, required). This is the name of the RabbitMQ datasource that is configured in datasources.json. Please note that this datasource does not use any loopback-connector-* packages, but just a way to tell the component how to connect to RabbitMQ.
acls (Array, optional). Use this array to configure the ACL's. This ACL protects the Queue model that gets created.

Topology

In the topology object you configure the queues served by this component. The object key is the name of the Queue.

Inside this queue definition you can define a consumer, a producer, or both. The consumer and producer objects both accept 2 properties, model and method.

Consumer

When you defined a consumer on a queue, the component will call into the Model.method() defined when a new message arrives on the queue. The method will be called with 2 parameters, payload and ack. Payload is the raw message from the queue. The ack parameter is a message that is used to acknowledge to the queue that the message is being handled. Make sure to acknowledge all messages, because RabbitMQ won't allow any other messages to be picked up until the message is acknowledged, making the queue come to a halt.

Producer

When defining a producer on a queue, the component will create the method Model.method() defined. The method created accepts 1 parameter, payload. The payload is the raw message that will be stored on the queue.

TODO

Add support for more types of Queues in the topology

License

MIT

rahulbile/loopback-component-mq