====== RabbitMQ ======
===== Configuration =====
==== Install ====
<code>
$ echo "deb http://www.rabbitmq.com/debian/ testing main" >> /etc/apt/sources.list
$ wget http://www.rabbitmq.com/rabbitmq-signing-key-public.asc
$ sudo apt-key add rabbitmq-signing-key-public.asc
$ sudo apt-get install rabbitmq-server
</code>
==== Commands ====
=== Manage the server ===
<code>
$ sudo service rabbitmq-server status
</code>
Where status can be ''start'', ''stop'', ''restart''...

=== See number of messages ===
<code>
$ sudo rabbitmqctl list_queues
</code>

=== Print not-acknowledge message ===
<code>
$ sudo rabbitmqctl list_queues name messages_ready messages_unacknowledged
</code>

=== Listing exchanges ===
<code>
$ sudo rabbitmqctl list_exchanges
</code>

=== List bindings ===
<code>
$ sudo rabbitmqctl list_bindings
</code>
==== Concepts ====
=== Exchanges ===
A producer can only send messages to an exchange. The exchange receives messages from producers and it pushes them to queues. 
  * direct
  * topic
  * headers
  * fanout: it broadcasts all the messages it receives to all the queues it knows.

Some amq.* exchanges and the default (unnamed) exchange are created by default, we identify the default exchange by the empty string.

To declare an exchange it's used:
<code python>
channel.exchange_declare(exchange='logs', type='fanout')
</code>

=== Bindings ===
The relationship between exchange and a queue is called a binding.
<code python>
channel.queue_bind(exchange='logs', queue=result.method.queue)
</code>

=== Temporary queues ===
Whe we want to hear about all messages and not just a subset of them. We need to connect to Rabbit with an empty queue. To do it we could let the server choose a random queue name for us. We can do this by not supplying the queue parameter to queue_declare:
<code python>
result = channel.queue_declare()
</code>
Also we need that once we disconnect the consumer the queue should be deleted. There's an exclusive flag for that:
<code python>
result = channel.queue_declare(exclusive=True)
</code>
===== Use =====
==== Producer & consumer ====
=== Producer ===
<code python>
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='hello')
for i in xrange(100):
    msg = 'Hello World! - ' + str(i)
    channel.basic_publish(exchange='', routing_key='hello', body=msg)
    print " [x] Sent", msg
connection.close()
</code>
=== Consumer ===
<code python>
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pika


def callback(ch, method, properties, body):
    print " [x] Received %r" % (body,)

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='hello')
print ' [*] Waiting for messages. To exit press CTRL+C'   
channel.basic_consume(callback, queue='hello', no_ack=True)
channel.start_consuming()
</code>
  * ''no_ack'' means //no acknowledgement// messages.
  * We can tell to Rabbit that do not deliver more than a message to a worker with ''prefetch_count=1'' into the worker channel.
==== Message acknowledgment and persistent queues ====
  * Message acknoledgement is done after connection dies.
    * Message acknoledgement is active by default, it is defined by ''no_ack'' parameter.
  * Persistent messages and queues are those which remain in the computer even if the computer or rabbit crash.
    * They are activated marking the queue as durable and the delivery_mode property with a value 2.

<code python>
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pika
import time


def callback(ch, method, properties, body):
    print " [x] Received %r" % (body,)
    time.sleep(body.count('.'))
    print " [x] Done"
    ch.basic_ack(delivery_tag=method.delivery_tag)

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='task_queue', durable=True)
print ' [*] Waiting for messages. To exit press CTRL+C'
channel.basic_qos(prefetch_count=1)
channel.basic_consume(callback, queue='task_queue')
channel.start_consuming()
</code>

<code python>
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='task_queue', durable=True)
message = ' '.join(sys.argv[1:]) or "Hello World!"
channel.basic_publish(exchange='',
                      routing_key='task_queue',
                      body=message,
                      properties=pika.BasicProperties(delivery_mode=2,))
print " [x] Sent %r" % (message,)
connection.close()
</code>

==== Publish\Subscriber ==== 

<code python>
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pika


def callback(ch, method, properties, body):
    print " [x] %r" % (body,)

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.exchange_declare(exchange='logs', type='fanout')
result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue
channel.queue_bind(exchange='logs', queue=queue_name)
print ' [*] Waiting for logs. To exit press CTRL+C'
channel.basic_consume(callback, queue=queue_name, no_ack=True)
channel.start_consuming()
</code>

<code python>
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.exchange_declare(exchange='logs', type='fanout')
message = ' '.join(sys.argv[1:]) or "info: Hello World!"
channel.basic_publish(exchange='logs', routing_key='', body=message)
print " [x] Sent %r" % (message,)
connection.close()
</code>
===== Others =====
==== Plugins ====
=== Management ===
<code>
$ rabbitmq-plugins enable rabbitmq_management
</code>
Will enable the web management server. You'll find at: [[http://server:15672]] (p.eg. [[http://127.0.0.1:15672/]]). Username ''guest'' and password ''guest'' is the authentication by default.

Para añadir usuarios:

  - you need to create a user for any vhost on that system (here I use default vhost "/")
<code>
$ rabbitmqctl add_user yourName yourPass
</code>
  - Set the permissions for that user for default vhost
<code>
$ rabbitmqctl set_permissions -p / yourName ".*" ".*" ".*"
</code>
  - Set the administrator tag for this user (to enable him access the management pluggin)
<code>
$ rabbitmqctl set_user_tags yourName administrator
</code>
==== Notes ====
=== Reset RabbitMQ ===
... Queues, config, everything!
<code>
$ rabbitmqctl stop_app
$ rabbitmqctl reset
$ rabbitmqctl start_app
</code>