queue again in GUI Update the “Hello world” to “Hello Larry”
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RabbitMQ Server
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RabbitMQ - Concept }
Publisher/Consumer is app (running in python container in exercise 1) }
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Publish & consume the messages
In RabbitMQ, An exchange receives messages from producers and pushes them to queues.
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Rabbit Libraries - Python Pika module } }
Pika is RabbitMQ server python module Procedure for Publish 1.
Establish connection
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Define Queue (“Hello”) Publish (routing_key is queue name)
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Consume } }
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1,2 same for publish 3: Call back
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Queue in depth }
Round-robin dispatching }
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Message acknowledgment }
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Scale to distribute to different consumers An ack(nowledgement) is sent back from the consumer to tell RabbitMQ that a particular message had been received
How to scale the twitter message image processing twitter.py – publish twitter message
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image.py – process the image if twitter has
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Env
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# cd ../exer2 #./twitter.py “I see the nice picture 1.png” #./image.py
Did we receive the message in queue ? Why ? } Run more image.py to see how it is distributed (another shell, docker exec -it .. ) } Kill some image.py }
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Exchange types Exchange type is the rule on how to deliver message to the queues: direct, fanout, topic and headers } Direct: if the routing key matches, then the message is delivered to the corresponding queue. } Fanout: multicast the received message to the bound queues. }
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Publish/Subscribe Patten Broadcast
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Exercise 3: Fanout - Publish/Subscribe }
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How to broadcast the message for different consumers } twitter.py – publish twitter message } image.py – manipulate the image if twitter has Env # cd ../exer3 #./twitter.py “I see the nice picture 1.png” #./image.py
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Did we receive first twitter & Check in the browser for the queue Implement extra tag.py check whether twitter has tag } } }
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Define queue `tag` and bind to `twitter` exchange Search for “#xxx#” keywords and print it out ./twitter.py “#codingwithme# is good, send picture 1.png” 7/22/15
Binding A binding is a relationship between an exchange and a queue. } One to one mapping }
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Multiple mapping with
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Routing_key
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Exercise 4: Direct - Routing } }
How to handle different log system Env # cd ../exer4 # ./emit_log_direct.py # ./receive_logs_direct.py
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Exercise:
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Check GUI for queue name and bindings
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More receiver # ./receive_logs_direct.py warning error > logs_from_rabbit.log # ./receive_logs_direct.py info warning error
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Define fixed queue name
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Topics } }
User pattern as routing key (“a.b.c.d”) Queues can use wildcard characters in binding } }
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* matches a single word, # zero or more words. “rabbit.*” matches for rabbit.info/rabbit.error
Topic exchange is powerful and can behave like other exchanges. } }
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When a queue is bound with "#" (hash) binding key - it will receive all the messages, regardless of the routing key - like in fanout exchange. When special characters "*" (star) and "#" (hash) aren't used in bindings, the topic exchange will behave just like a direct one.
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Exercise 5: Topic } }
handle different log system more Env # cd ../exer5 # ./emit_log_direct.py # ./receive_logs_direct.py “#”
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Exercise } } }
Check the queue name in GUI Create for rabbit.*/apache.*/*.info Publish message for rabbit.info/error & apache.info/ error
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Summary }
RabbitMQ is the message broker support AMQP }
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Handle async messages
AMQP Model } } } }
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Different Exchange types Messages Queues Bindings Rule for Binding ..
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Reference } } }
http://www.rabbitmq.com/ Exercises are based on http://www.rabbitmq.com/getstarted.html Book: }
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RabbitMQ in Action (2012): http://www.manning.com/videla/
