Stapfen

Stapfen is a simple gem to make writing workers that consume messages via STOMP or JMS easier.

Stapfen allows you to write one worker class, and use either protocol depending on the environment and needs.

RDoc here

Usage

(Examples can be found in the examples/ directory)

Consider the following myworker.rb file:

class MyWorker < Stapfen::Worker
  use_stomp!

  configure do
    {
      :hosts => [
        {
          :host => 'localhost',
          :port => 61613,
          :login => 'guest',
          :passcode => 'guest',
          :ssl => false
        }
      ]
    }
  end

  # [Optional] Set up a logger for each worker instance
  log do
    Logger.new(STDOUT)
  end

  consume 'thequeue', :dead_letter_queue => '/queue/dlq',
                      :max_redeliveries => 0 do |message|

    data = expensive_computation(message.body)
    # Save my data, or do something worker-specific with it
    persist(data)

    # Send another message
    client.publish('/topic/computation-acks', "finished with #{message.message_id}")
  end

end

MyWorker.run!

When using the STOMP protocol, the value returned from the configure block is expected to be a valid Stomp::Client connection hash.

In the case of the JMS protocol, the value returned from the configure block is expected to be a valid configuration hash for the jruby-jms gem.

---

It is also important to note that the consume block will be invoked inside an instance of MyWorker and will execute inside its own Thread, so take care when accessing other shared resources.

Fallback and dead-letter-queue support

The consume block accepts the usual subscriptions headers, as well as two additional headers :dead_letter_queue and :max_redeliveries. If either of the latter two is present, the consumer will unreceive any messages for which the block returns false; after :max_redeliveries, it will send the message to :dead_letter_queue. consume blocks without these headers will fail silently rather than unreceive.

Installation

Add this line to your application's Gemfile:

gem 'stapfen'

And then execute:

$ bundle

Or install it yourself as:

$ gem install stapfen