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...

bundle exec 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

FIRST: Read our style guides at https://github.com/teamsnap/guides/tree/master/ruby

1. Fork it ( http://github.com/emque/emque-producing/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.