Class: NebulousStomp::Listener

Inherits:
Object
  • Object
show all
Defined in:
lib/nebulous_stomp/listener.rb

Overview

Implements the Request-Response use case; consume Requests from an input queue and send Responses.

listener = NebulousStomp::Listener.new(target)
listener.consume_messages do |msg|
  begin

    case msg.verb
      when "ping"
        listener.reply *msg.respond_with_success
      when "time"
        listener.reply *msg.respond_with_protocol("timeresponce", Time.now)
      else
        listener.reply *msg.respond_with_error("Bad verb #{msg.verb}")
    end

  rescue
    listener.reply *msg.respond_with_error($!)
  end
end

loop { sleep 5 }

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(queue) ⇒ Listener

When creating a Listener, pass the queue name to listen on.

This can be something stringlike, or a Target (in which case we listen on the target’s receiving queue).



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# File 'lib/nebulous_stomp/listener.rb', line 46

def initialize(queue)
  case 
    when queue.respond_to?(:receive_queue) then @queue = queue.receive_queue
    when queue.respond_to?(:to_s)          then @queue = queue.to_s
    else fail ArgumentError, "Unknown object passed as queue"
  end

  NebulousStomp.logger.debug(__FILE__) { "Listening on #@queue" }
end

Instance Attribute Details

#queue ⇒ Object (readonly)

the queue name we are listening to



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# File 'lib/nebulous_stomp/listener.rb', line 35

def queue
  @queue
end

#stomp_handler=(value) ⇒ Object

Insert a StompHandler object for test purposes



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# File 'lib/nebulous_stomp/listener.rb', line 38

def stomp_handler=(value)
  @stomp_handler = value
end

Instance Method Details

#consume_messages ⇒ Object

:call-seq: listener.consume_message(queue) {|msg| … }

Consume messages from the queue, yielding each.

Note that we don’t block for input here. Just as with the Stomp gem, and with StompHandler, you will need to take your own measures to ensure that your program does not end when it should be waiting for messages to arrive. The simplest solution is something like:

loop { sleep 5 }

Note also that this method runs inside a Thread, and so does the block you pass to it. By default threads do not report errors, so you must arrange to do that yourself.



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# File 'lib/nebulous_stomp/listener.rb', line 71

def consume_messages
  stomp_handler.listen(@queue) {|msg| yield msg }
end

#quit ⇒ Object

Disconnect from Stomp.

You probably don’t need this; Stomp connections are quite short lived.



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# File 'lib/nebulous_stomp/listener.rb', line 92

def quit
  stomp_handler.stomp_disconnect
  self
end

#reply(queue, message) ⇒ Object

Send a message in reply

Queue must be a queue name; message must be a Message. The usual way to get these is from the Message class, for example by calling ‘message.respond_with_success`.



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# File 'lib/nebulous_stomp/listener.rb', line 81

def reply(queue, message)
  NebulousStomp.logger.debug(__FILE__) { "Replying to #{queue}" }
  stomp_handler.send_message(queue, message)
  self
end