#!/usr/bin/env python # # Licensed to the Apache Software Foundation (ASF) under one # or more contributor license agreements. See the NOTICE file # distributed with this work for additional information # regarding copyright ownership. The ASF licenses this file # to you under the Apache License, Version 2.0 (the # "License"); you may not use this file except in compliance # with the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, # software distributed under the License is distributed on an # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY # KIND, either express or implied. See the License for the # specific language governing permissions and limitations # under the License. # """ 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): 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(timeout=10) content = message.body session.message_accept(RangedSet(message.id)) print content except Empty: print "No more messages!" return def subscribe_queue(server_queue_name, local_queue_name): print "Subscribing local queue '" + local_queue_name + "' to " + server_queue_name + "'" queue = session.incoming(local_queue_name) session.message_subscribe(queue=server_queue_name, destination=local_queue_name) queue.start() return queue #----- Initialization -------------------------------------- # Set parameters for login host="127.0.0.1" port=5672 user="guest" password="guest" # If an alternate host or port has been specified, use that instead # (this is used in our unit tests) if len(sys.argv) > 1 : host=sys.argv[1] if len(sys.argv) > 2 : port=int(sys.argv[2]) # Create a connection. socket = connect(host, port) connection = Connection (sock=socket, username=user, password=password) connection.start() session = connection.session(str(uuid4())) #----- Main Body -- ---------------------------------------- # declare queues on the server news = "news-" + session.name weather = "weather-" + session.name usa = "usa-" + session.name europe = "europe-" + session.name 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() # Subscribe local queues to server queues local_news = "local_news" local_weather = "local_weather" local_usa = "local_usa" local_europe = "local_europe" local_news_queue = subscribe_queue(news, local_news) local_weather_queue = subscribe_queue(weather, local_weather) local_usa_queue = subscribe_queue(usa, local_usa) local_europe_queue = subscribe_queue(europe, local_europe) # Call dump_queue to print messages from each queue print "Messages on 'news' queue:" dump_queue(local_news_queue) print "Messages on 'weather' queue:" dump_queue(local_weather_queue) print "Messages on 'usa' queue:" dump_queue(local_usa_queue) print "Messages on 'europe' queue:" dump_queue(local_europe_queue) #----- Cleanup ------------------------------------------------ # Clean up before exiting so there are no open threads. session.close(timeout=10)