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Diffstat (limited to 'python/examples/pubsub/topic_subscriber.py')
-rw-r--r-- | python/examples/pubsub/topic_subscriber.py | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/python/examples/pubsub/topic_subscriber.py b/python/examples/pubsub/topic_subscriber.py new file mode 100644 index 0000000000..08682f0674 --- /dev/null +++ b/python/examples/pubsub/topic_subscriber.py @@ -0,0 +1,124 @@ +#!/usr/bin/env python +""" + topic_subscriber.py + + This subscriber creates private queues and binds them + to the topics "usa.#", "europe.#", "#.news", and "#.weather". +""" + +import base64 + +import qpid +from qpid.client import Client +from qpid.content import Content +from qpid.queue import Empty + +#----- Functions ------------------------------------------- + +def dump_queue(client, queue_name): + + print "Messages queue: " + queue_name + + consumer_tag = queue_name # Use the queue name as the consumer tag - need a unique tag + queue = client.queue(consumer_tag) + + # Call basic_consume() 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 basic_consume() 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.content.body + 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="127.0.0.1" +port=5672 +amqp_spec="/usr/share/amqp/amqp.0-10-preview.xml" +user="guest" +password="guest" + +# Create a client and log in to it. + +spec = qpid.spec.load(amqp_spec) +client = Client(host, port, spec) +client.start({"LOGIN": user, "PASSWORD": password}) + +session = client.session() +session_info = session.session_open() +session_id = session_info.session_id + +#----- Main Body -- ---------------------------------------- + + +news = "news" + base64.urlsafe_b64encode(session_id) +weather = "weather" + base64.urlsafe_b64encode(session_id) +usa = "usa" + base64.urlsafe_b64encode(session_id) +europe = "europe" + base64.urlsafe_b64encode(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.queue_bind(exchange="amq.topic", queue=news, routing_key="#.news") +session.queue_bind(exchange="amq.topic", queue=weather, routing_key="#.weather") +session.queue_bind(exchange="amq.topic", queue=usa, routing_key="usa.#") +session.queue_bind(exchange="amq.topic", queue=europe, routing_key="europe.#") + +# Bind each queue to the control queue so we know when to stop + +session.queue_bind(exchange="amq.topic", queue=news, routing_key="control") +session.queue_bind(exchange="amq.topic", queue=weather, routing_key="control") +session.queue_bind(exchange="amq.topic", queue=usa, routing_key="control") +session.queue_bind(exchange="amq.topic", queue=europe, routing_key="control") + +# Remind the user to start the topic producer + +print "Queues create - please start the topic producer" + +# Call dump_queue to print messages from each queue + +dump_queue(client, news) +dump_queue(client, weather) +dump_queue(client, usa) +dump_queue(client, europe) + +#----- Cleanup ------------------------------------------------ + +# Clean up before exiting so there are no open threads. + +session.session_close() |