ericflopsy.py

"""
Copyright (c) 2008-2009, Nathan Borror, and modified heavily by Eric Florenzano
All rights reserved.
 
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
 
Redistributions of source code must retain the above copyright notice, this list
of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
Neither the name of the ericflopsy nor the names of its contributors may be
used to endorse or promote products derived from this software without specific
prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Ericflopsy
======

A very simple way to interact with python AMQPlib. For my case I'm using
RabbitMQ as my implementation but it should work with others.

Consumer
--------

>>> import ericflopsy
>>> consumer = ericflopsy.Consumer()
>>> def print_message(message):
...     print 'Recieved: ' + message.body
...     consumer.channel.basic_ack(message.delivery_tag)
... 
>>> consumer.register('messages_to_print', print_message)
>>> def print_message_in_caps(message):
...     print 'Received: ' + message.body.upper()
...     consumer.channel.basic_ack(message.delivery_tag)
...
>>> consumer.register('messages_to_print_in_caps', print_message_in_caps)
>>> consumer.wait()

Publisher
---------

>>> import ericflopsy
>>> publisher = ericflopsy.Publisher()
>>> publisher.publish('messages_to_print', 'Test message!')
>>> publisher.publish('messages_to_print_in_caps', 'hello, world!')
"""

import simplejson
import uuid

from amqplib import client_0_8 as amqp

DEFAULT_HOST = '127.0.0.1'
DEFAULT_USER_ID = 'guest'
DEFAULT_PASSWORD = 'guest'
DEFAULT_VHOST = '/'
DEFAULT_PORT = 5672
DEFAULT_INSIST = False
DEFAULT_QUEUE = 'default_queue'
DEFAULT_ROUTING_KEY = 'default_routing_key'
DEFAULT_EXCHANGE = 'default_exchange'
DEFAULT_DURABLE = True
DEFAULT_EXCLUSIVE = False
DEFAULT_AUTO_DELETE = False
DEFAULT_DELIVERY_MODE = 2
try:
    from django.conf import settings
    DEFAULT_HOST = getattr(settings, 'AMQP_SERVER', DEFAULT_HOST)
    DEFAULT_USER_ID = getattr(settings, 'AMQP_USER', DEFAULT_USER_ID)
    DEFAULT_PASSWORD = getattr(settings, 'AMQP_PASSWORD', DEFAULT_PASSWORD)
    DEFAULT_VHOST = getattr(settings, 'AMQP_VHOST', DEFAULT_VHOST)
    DEFAULT_PORT = getattr(settings, 'AMQP_PORT', DEFAULT_PORT)
    DEFAULT_INSIST = getattr(settings, 'AMQP_INSIST', DEFAULT_INSIST)
    DEFAULT_QUEUE = getattr(settings, 'AMQP_QUEUE', DEFAULT_QUEUE)
    DEFAULT_ROUTING_KEY = getattr(settings, 'AMQP_ROUTING_KEY', DEFAULT_ROUTING_KEY)
    DEFAULT_EXCHANGE = getattr(settings, 'AMQP_EXCHANGE', DEFAULT_EXCHANGE)
    DEFAULT_DURABLE = getattr(settings, 'AMQP_DURABLE', DEFAULT_DURABLE)
    DEFAULT_EXCLUSIVE = getattr(settings, 'AMQP_EXCLUSIVE', DEFAULT_EXCLUSIVE)
    DEFAULT_AUTO_DELETE = getattr(settings, 'AMQP_AUTO_DELETE', DEFAULT_AUTO_DELETE)
    DEFAULT_DELIVERY_MODE = getattr(settings, 'AMQP_DELIVERY_MODE', DEFAULT_DELIVERY_MODE)
except ImportError:
    pass


class Connection(object):
    def __init__(self, host=DEFAULT_HOST, user_id=DEFAULT_USER_ID,
        password=DEFAULT_PASSWORD, vhost=DEFAULT_VHOST, port=DEFAULT_PORT,
        insist=DEFAULT_INSIST):
        
        self.host = host
        self.user_id = user_id
        self.password = password
        self.vhost = vhost
        self.port = port
        self.insist = insist
        
        self.connect()

    def connect(self):
        self.connection = amqp.Connection(
            host='%s:%s' % (self.host, self.port),
            userid=self.user_id,
            password=self.password,
            virtual_host=self.vhost,
            insist=self.insist
        )


class Consumer(object):
    def __init__(self, routing_key=DEFAULT_ROUTING_KEY,
        exchange=DEFAULT_EXCHANGE, queue=DEFAULT_QUEUE,
        durable=DEFAULT_DURABLE, exclusive=DEFAULT_EXCLUSIVE,
        auto_delete=DEFAULT_AUTO_DELETE, connection=None):
        
        self.callbacks = {}
        
        self.routing_key = routing_key
        self.exchange = exchange
        self.queue = queue
        self.durable = durable
        self.exclusive = exclusive
        self.auto_delete = auto_delete
        self.connection = connection or Connection()
        self.channel = self.connection.connection.channel()
        
        self.channel.queue_declare(
            queue=self.queue,
            durable=self.durable,
            exclusive=self.exclusive,
            auto_delete=self.auto_delete
        )
        self.channel.exchange_declare(
            exchange=self.exchange,
            type='direct',
            durable=self.durable,
            auto_delete=self.auto_delete
        )
        self.channel.queue_bind(
            queue=self.queue,
            exchange=self.exchange,
            routing_key=self.routing_key
        )
        self.channel.basic_consume(
            queue=self.queue,
            no_ack=True, 
            callback=self.dispatch,
            consumer_tag=str(uuid.uuid4())
        )

    def close(self):
        if getattr(self, 'channel'):
            self.channel.close()
        if getattr(self, 'connection'):
            self.connection.close()

    def wait(self):
        while True:
            self.channel.wait()
    
    def dispatch(self, message):
        decoded = simplejson.loads(message.body)
        message.body = decoded['data']
        callback = self.callbacks.get(decoded['kind'])
        if callback:
            callback(message)

    def register(self, kind, callback):
        self.callbacks[kind] = callback
    
    def unregister(self, kind):
        del self.callbacks[kind]


class Publisher(object):
    def __init__(self, routing_key=DEFAULT_ROUTING_KEY,
        exchange=DEFAULT_EXCHANGE, connection=None,
        delivery_mode=DEFAULT_DELIVERY_MODE):
        
        self.connection = connection or Connection()
        self.channel = self.connection.connection.channel()
        self.exchange = exchange
        self.routing_key = routing_key
        self.delivery_mode = delivery_mode

    def publish(self, kind, message_data):
        encoded = simplejson.dumps({'kind': kind, 'data': message_data})
        message = amqp.Message(encoded)
        message.properties['delivery_mode'] = self.delivery_mode
        self.channel.basic_publish(
            message,
            exchange=self.exchange,
            routing_key=self.routing_key
        )
        return message

    def close(self):
        if getattr(self, 'channel'):
            self.channel.close()
        if getattr(self, 'connection'):
            self.connection.connection.close()