RabbitMQ Notes
RabbitMQ is a broker that accepts messages from producers and delivers
them to consumers . It routes, buffers or persists the messages according
to rules. Everything about RabbitMQ is superb, from the design to the webpage
documentation and tutorials. These notes will be commensurately sparser for it.
See
RabbitMQ Tutorials: Introduction .
Terminology and concepts
producing
consuming
queue
exchange
Typically, the producer , broker and consumer do not
live on the same host.
It's a core principle of RabbitMQ that a producer never sends any message
directly to a queue, but to an exchange. The exchange determines what to
do with the message. This depends on how it's supposed to be used:
Append it to a particular queue?
Append to many queues?
Discard it?
Exchange types
direct
topid
headers
fanout to all queues, publish
Publish to a named exchange:
channel.basicPublish( "myExchange", "", null, message );
Temporary queues
These are created unnamed, by calling queueDeclare() without a
name. Once the consumer is disconnected, the queue is automatically
deleted.
String queueName = channel.queueDeclare().getQueue();
Bind a queue to an exchange:
channel.queueBind( queueName, "myExchange", "" );
Visualize the mechanics...
This is a very simplified view.
Installation
Download from
Downloading and Installing RabbitMQ . This amounts exactly to
The Java client which consists of a bunch of JARs including and in
particular, rabbitmq-client.jar , which you'll link at least
to accomplish the tutorials noted above.
The server, as a Debian or other download. This depends on other
technology (Erlang) as shown below. Once installed, it's running
and ready to accommodate the tutorial exercises.
~/Downloads/rabbitmq $ sudo dpkg -i rabbitmq-server_3.1.3-1_all.deb sudo bash apt-get install erlang-nox apt-get -f install dpkg -i rabbitmq-server_3.1.3-1_all.deb