notifications
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	#!/usr/bin/env python3

	# -------------------------------------------------------------
	# Notifications center - CLI client
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
	# Author: Sébastien Santoro aka Dereckson
	# Project: Nasqueron
	# Created: 2016-01-27
	# Description: Connects to the message broker, subscribes to
	# the notifications exchange, consumes messages,
	# prints them on the console
	# Dependencies: Pika, direct access to the broker
	# -------------------------------------------------------------

	import configparser
	import json
	import pika
	import sys
	import time

	# -------------------------------------------------------------
	# Helper functions to parse config and connect to the broker
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	def getConfig ():
	config = configparser.ConfigParser()
	config.read('/usr/local/etc/notifications.conf')
	return config

	def getCredentials(config):
	return pika.PlainCredentials(
	username=config['Broker']['User'],
	password=config['Broker']['Password'],
	erase_on_connect=True
	)

	def getBrokerConnection(config):
	parameters = pika.ConnectionParameters(
	host=config['Broker']['Host'],
	virtual_host=config['Broker']['Vhost'],
	credentials=getCredentials(config)
	)
	return pika.BlockingConnection(parameters)

	def getExchange(config):
	return config['Broker']['Exchange']

	def getBrokerQueue(channel, exchange):
	channel.exchange_declare(exchange=exchange, type='topic')
	result = channel.queue_declare(exclusive=True)
	return result.method.queue

	# -------------------------------------------------------------
	# Helper functions to format the output
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	def getNotificationFormat():
	return "[{time}] <{project}/{group}> {text}"

	def getNotificationText(notification):
	text = notification['text']
	if notification['link']:
	text += " — " + notification['link']
	return text

	def formatNotification(notificationMessage):
	notification = json.loads(notificationMessage)
	return getNotificationFormat().format(
	time=time.strftime("%H:%M:%S"),
	project=notification['project'],
	group=notification['group'],
	text=getNotificationText(notification)
	)

	# -------------------------------------------------------------
	# Callbacks
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	def onBrokerMessage(channel, basic_deliver, properties, body):
	notification = formatNotification(body.decode("utf-8"))
	print(notification)
	channel.basic_ack(basic_deliver.delivery_tag)

	# -------------------------------------------------------------
	# Services providers
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	def getConnection (config):
	try:
	return getBrokerConnection(config)
	except pika.exceptions.ProbableAccessDeniedError:
	print("Can't login to the broker: it's probably an access denied case.", file=sys.stderr)
	sys.exit(2)

	def getChannel (config):
	return getConnection(config).channel()

	def getQueue (channel, exchange):
	try:
	return getBrokerQueue(channel, exchange)
	except pika.exceptions.ChannelClosed as e:
	print("Channel error: {0}".format(e))
	sys.exit(4)

	# -------------------------------------------------------------
	# Services container
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	def initializeApplication ():
	app = {}

	app['config'] = getConfig()
	app['options'] = {}
	app['channel'] = getChannel(app['config'])
	app['exchange'] = getExchange(app['config'])
	app['queue'] = getQueue(app['channel'], app['exchange'])

	return app

	# -------------------------------------------------------------
	# Main tasks
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	def parseArguments (options):
	#Todo: allows an option --routing-key <key>
	options['BindingKeys'] = ['#']

	def subscribeToNotifications (options, channel, exchange, queue):
	for binding_key in options['BindingKeys']:
	subscribeToNotificationsForTopic(binding_key, channel, exchange, queue)

	def subscribeToNotificationsForTopic(binding_key, channel, exchange, queue):
	try:
	channel.queue_bind(exchange=exchange,
	queue=queue,
	routing_key=binding_key)
	except pika.exceptions.ChannelClosed as e:
	print("Channel error: {0}".format(e))
	sys.exit(8)

	def consumeNotifications (channel, queue):
	channel.basic_consume(onBrokerMessage, queue=queue)
	channel.start_consuming()

	# -------------------------------------------------------------
	# Procedural code
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	app = initializeApplication();
	parseArguments(app['options']);
	subscribeToNotifications(app['options'], app['channel'], app['exchange'], app['queue'])
	consumeNotifications(app['channel'], app['queue'])

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	dereckson
	Feb 20 2016, 12:37

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