Tackle

Tackles the problem of processing asynchronous jobs in reliable manner by relying on RabbitMQ.

You should also take a look at Ruby Tackle.

Why should I use tackle?

• It is ideal for fast microservice prototyping
• It uses sane defaults for queue and exchange creation
• It retries messages that fail to be processed
• It stores unprocessed messages into a dead queue for later inspection

Installation

Add the following to the list of your dependencies:

def deps do
  [
    {:tackle, github: "renderedtext/ex-tackle"}
  ]
end

Also, add it to the list of your applications:

def application do
  [applications: [:tackle]]
end

Publishing messages to an exchange

To publish a message to an exchange:

options = %{
  url: "amqp://localhost",
  exchange: "test-exchange",
  routing_key: "test-messages",
}

Tackle.publish("Hi!", options)

Consuming messages from an exchange

First, declare a consumer module:

defmodule TestConsumer do
  use Tackle.Consumer,
    url: "amqp://localhost",
    exchange: "test-exchange",
    routing_key: "test-messages",
    service: "my-service"

  def handle_message(message) do
    IO.puts "A message arrived. Life is good!"

    IO.puts message
  end
end

And then start it to consume messages:

TestConsumer.start_link

Rescuing dead messages

If you consumer is broken, or in other words raises an exception while handling messages, your messages will end up in a dead messages queue.

To rescue those messages, you can use Tackle.republish:

dead_queue_name = "my-service.test-message.dead"

options = {
  url: "amqp://localhost",
  qeueu: dead_queue_name,
  exchange: "test-exchange",
  routing_key: "test-messages",
  count: 1
}

Tackle.republish(options)

The above will pull one message from the dead_queue_name and publish it on the test-exchange exchange with test-messages routing key.

To republish multiple messages, use a bigger count number.