Class: Bunny::Subscription

Inherits:
Consumer show all
Defined in:
lib/bunny/subscription08.rb

Overview

=== DESCRIPTION:

Asks the server to start a “consumer”, which is a transient request for messages from a specific queue. Consumers last as long as the channel they were created on, or until the client cancels them with an unsubscribe. Every time a message reaches the queue it is passed to the blk for processing. If error occurs, Bunny_::_ProtocolError is raised.

==== OPTIONS:

  • :consumer_tag => ‘tag’ – Specifies the identifier for the consumer. The consumer tag is local to a connection, so two clients can use the same consumer tags. If this option is not specified a server generated name is used.
  • :ack => false (default) or true – If set to false, the server does not expect an acknowledgement message from the client. If set to true, the server expects an acknowledgement message from the client and will re-queue the message if it does not receive one within a time specified by the server.
  • :exclusive => true or false (default) – Request exclusive consumer access, meaning only this consumer can access the queue.
  • :nowait => true or false (default) – Ignored by Bunny, always false.
  • :timeout => number of seconds – The subscribe loop will continue to wait for messages until terminated (Ctrl-C or kill command) or this timeout interval is reached.
  • :message_max => max number messages to process – When the required number of messages is processed subscribe loop is exited.

==== OPERATION:

Passes a hash of message information to the block, if one has been supplied. The hash contains :header, :payload and :delivery_details. The structure of the data is as follows -

:header has instance variables - @klass @size @weight @properties is a hash containing - :content_type :delivery_mode :priority

:payload contains the message contents

:delivery details is a hash containing - :consumer_tag :delivery_tag :redelivered :exchange :routing_key

If the :timeout option is specified then the subscription will automatically cease if the given number of seconds passes with no message arriving.

==== EXAMPLES

my_queue.subscribe(:timeout => 5) {|msg| puts msg[:payload]}

my_queue.subscribe(:message_max => 10, :ack => true) {|msg| puts msg[:payload]}

Instance Attribute Summary

Attributes inherited from Qrack::Subscription

#ack, #break_when_empty, #client, #consumer_tag, #delivery_tag, #exclusive, #message_count, #message_max, #queue, #timeout

Instance Method Summary collapse

Methods inherited from Consumer

#initialize

Methods inherited from Qrack::Subscription

#initialize, #start

Constructor Details

This class inherits a constructor from Bunny::Consumer

Instance Method Details

#setup_consumer ⇒ Object 



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# File 'lib/bunny/subscription08.rb', line 67

def setup_consumer
  subscription_options = {
    :queue => queue.name,
    :consumer_tag => consumer_tag,
    :no_ack => !ack,
    :exclusive => exclusive,
    :nowait => false
  }.merge(@opts)

  client.send_frame(Qrack::Protocol::Basic::Consume.new(subscription_options))

  method = client.next_method

  client.check_response(method, Qrack::Protocol::Basic::ConsumeOk, "Error subscribing to queue #{queue.name}")

  @consumer_tag = method.consumer_tag
end