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#!/usr/bin/env python
"""
topic_subscriber.py
This subscriber creates private queues and binds them
to the topics 'usa.#', 'europe.#', '#.news', and '#.weather'.
"""
import qpid
import sys
import os
from qpid.util import connect
from qpid.connection import Connection
from qpid.datatypes import Message, RangedSet, uuid4
from qpid.queue import Empty
#----- Functions -------------------------------------------
def dump_queue(queue_name):
print "Messages queue: " + queue_name
consumer_tag = queue_name # Use the queue name as the consumer tag - need a unique tag
queue = session.incoming(consumer_tag)
# Call message_subscribe() to tell the broker to deliver messages
# from the AMQP queue to a local client queue. The broker will
# start delivering messages as soon as message_subscribe() is called.
session.message_subscribe(queue=queue_name, destination=consumer_tag)
session.message_flow(consumer_tag, 0, 0xFFFFFFFF)
session.message_flow(consumer_tag, 1, 0xFFFFFFFF)
content = "" # Content of the last message read
final = "That's all, folks!" # In a message body, signals the last message
message = 0
while content != final:
try:
message = queue.get()
content = message.body
session.message_accept(RangedSet(message.id))
print content
except Empty:
#if message != 0:
# message.complete(cumulative=True)
print "No more messages!"
return
# Messages are not removed from the queue until they
# are acknowledged. Using multiple=True, all messages
# in the channel up to and including the one identified
# by the delivery tag are acknowledged. This is more efficient,
# because there are fewer network round-trips.
#if message != 0:
# message.complete(cumulative=True)
#----- Initialization --------------------------------------
# Set parameters for login
host=len(sys.argv) > 1 and sys.argv[1] or "127.0.0.1"
port=len(sys.argv) > 2 and int(sys.argv[2]) or 5672
user="guest"
password="guest"
amqp_spec=""
try:
amqp_spec = os.environ["AMQP_SPEC"]
except KeyError:
amqp_spec="/usr/share/amqp/amqp.0-10.xml"
# Create a connection.
conn = Connection (connect (host,port), qpid.spec.load(amqp_spec))
conn.start()
session_id = str(uuid4())
session = conn.session(session_id)
#----- Main Body -- ----------------------------------------
news = "news" + session_id
weather = "weather" + session_id
usa = "usa" + session_id
europe = "europe" + session_id
session.queue_declare(queue=news, exclusive=True)
session.queue_declare(queue=weather, exclusive=True)
session.queue_declare(queue=usa, exclusive=True)
session.queue_declare(queue=europe, exclusive=True)
# Routing keys may be "usa.news", "usa.weather", "europe.news", or "europe.weather".
# The '#' symbol matches one component of a multipart name, e.g. "#.news" matches
# "europe.news" or "usa.news".
session.exchange_bind(exchange="amq.topic", queue=news, binding_key="#.news")
session.exchange_bind(exchange="amq.topic", queue=weather, binding_key="#.weather")
session.exchange_bind(exchange="amq.topic", queue=usa, binding_key="usa.#")
session.exchange_bind(exchange="amq.topic", queue=europe, binding_key="europe.#")
# Bind each queue to the control queue so we know when to stop
session.exchange_bind(exchange="amq.topic", queue=news, binding_key="control")
session.exchange_bind(exchange="amq.topic", queue=weather, binding_key="control")
session.exchange_bind(exchange="amq.topic", queue=usa, binding_key="control")
session.exchange_bind(exchange="amq.topic", queue=europe, binding_key="control")
# Remind the user to start the topic producer
print "Queues created - please start the topic producer"
sys.stdout.flush()
# Call dump_queue to print messages from each queue
dump_queue(news)
dump_queue(weather)
dump_queue(usa)
dump_queue(europe)
#----- Cleanup ------------------------------------------------
# Clean up before exiting so there are no open threads.
session.close(timeout=10)
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