Emque Producing

Define and send messages with Ruby to a variety of message brokers. The only currently supported message broker is RabbitMQ

This is a library that pairs nicely with Emque Consuming, a framework for consuming and routing messages to your code.

Installation

Add these lines to your application's Gemfile, depending on your message broker:

# for RabbitMQ, bunny is used
gem "emque-producing"
gem "bunny", "~> 1.7"

And then execute:

$ bundle

Or install it yourself as:

$ gem install emque-producing

Usage

# configure (likely in a Rails initializer)
require 'emque-producing'
Emque::Producing.configure do |c|
  c.app_name = "app"
  c.publishing_adapter = :rabbitmq
  c.rabbitmq_options[:url] = "amqp://guest:guest@localhost:5672"
  c.error_handlers << Proc.new {|ex,context|
   # notify/log
  }
end

# create a message class
class MyMessage
  include Emque::Producing::Message
  topic "topic1"
  message_type "mymessage.new"

  values do
    attribute :first_property, Integer, :required => true
    attribute :another_property, String, :required => true
  end
end

# produce message
message = MyMessage.new({:first_property => 1, :another_property => "another"})
message.publish

# create a message class including changesets
class MyChangesetMessage
  include Emque::Producing.message(:with_changeset => true)
  topic "topic1"
  message_type "mymessage.new"

  # Need to override an attribute name in the changeset? Simply define
  # the old name and new name here. This can be useful for ensuring
  # messages are consistent across varying producers.
  translate_changeset_attrs :old_attr_name => :new_attr_name
end

produced_message = TestMessageWithChangeset.new(
  :updated => {:old_attr_name => "Event"},
  :original => {:old_attr_name => "Game"}
)
json = produced_message.to_json
consumed_message = Oj.load(json)
expect(consumed_message["change_set"]).to eql(
  {
    "original"=>{"new_attr_name"=>"Game"},
    "updated"=>{"new_attr_name"=>"Event"},
    "delta"=>{
      "new_attr_name"=>{
        "original"=>"Game", "updated"=>"Event"
      }
    }
  }
)

For a more thorough guide to creating new messages and/or message producing applications, please read the wiki entry

Requirements

• Ruby 1.9.3 or higher
• RabbitMQ 3.x
• Bunny 1.4.x

Tests

To run tests...

rspec

If you would like to test the gem as part of your client, you can update the configuration option publish_messages to false like so:

    Emque::Producing.configure do |c|
      c.publish_messages = false
    ...other options
    end

This will prevent Emque from actually attempting to make the connection to your adapter which may be convenient in the case of CI environments.

Contributing

1. Fork it ( http://github.com/teamsnap/emquemessages/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

Roadmap

Kafka would make for a good adapter to be added to emque-producing. Anyone wishing to submit a PR can use the RabbitMQ adapter as a model.