#summary Start to finish example of sending and receiving

= Ten Minute Introduction =

We create a simple message consumer to receive messages, and a rails web controller that allows you to send a message when you click a button.  This example uses the stomp adapter and an activemq message broker, but other brokers and adapters are now available.

= Steps =

Start ActiveMQ

{{{ 
bin/activemq 
}}}

Create the rails application

{{{
rails demo
}}}

Add the activemessaging plugin

{{{
script/plugin install http://activemessaging.googlecode.com/svn/trunk/plugins/activemessaging
}}}

Create a processor

{{{
script/generate processor HelloWorld
}}}

This does the following if they don't exist already:
 * add the 'config/broker.yml' file to specify broker connections by environment
 * add the 'config/messaging.rb' file to map Stomp destinations to symbolic names
 * add the 'app/processor' folder where all prcessors that handle messages go
 * add the 'app/processor/application.rb' !ApplicationProcessor class, parent to all processors

For your particular !HelloWorld processor:
 * add the 'app/processor/hello_world_processor.rb'

By default, the processor will be subscribed to a queue ':hello_world'

{{{
class HelloWorldProcessor < ApplicationProcessor

  subscribes_to :hello_world

  def on_message(message)
    logger.debug "received: " + message
  end

end
}}}

If the generator created a new 'config/messaging.rb', it will have by default the queue symbol name to Stomp destination mapping:

{{{
    s.destination :hello_world, '/queue/HelloWorld'
}}}

Create a controller with an index action. We will use this to send our messages

{{{
script/generate controller SayHelloWorld index
}}}
	
Add the following to the new controller to allow us to access activemessaging

{{{
require 'activemessaging/processor'
include ActiveMessaging::MessageSender

publishes_to :hello_world
}}}

Modify the controller to send a message

{{{
def say_hello
  publish :hello_world, "<say>Hello World!</say>"
end
}}}

Add a button to send the message

{{{
<%=button_to "Say Hello", :action=>"say_hello" %>
}}}

Send a message. Browse to {{{http://localhost:3000/say_hello_world}}} and click the "Say Hello" button.

This adds a say action to the queue, which automatically gets created on first request. 

Now, to begin consuming the queue, start the `poller.rb` script by running the poller daemon script:
{{{
script/poller run
}}}

The Processor logs the message to the console.