What AMQP gem is

Simple asynchronous AMQP driver for Ruby/EventMachine This library works with Ruby 1.8, Ruby 1.9, JRuby and Rubinius, and is licensed under the Ruby License.

This library was tested primarily with RabbitMQ, although it should be compatible with any server implementing the AMQP 0-8 spec.

Getting started

To use examples with RabbitMQ, first install the broker. If you have Mercurial and Erlang/OTP installed, here is how to do it in 4 lines:

hg clone http://hg.rabbitmq.com/rabbitmq-codegen
hg clone http://hg.rabbitmq.com/rabbitmq-server
cd rabbitmq-server
make run

Then have a look at the various bundled examples:

ruby examples/mq/pingpong.rb   # 1-1 communication using amq.direct
ruby examples/mq/clock.rb      # 1-N communication using amq.fanout
ruby examples/mq/stocks.rb     # 1-subscriber communication using amq.topic

ruby examples/mq/multiclock.rb # header based routing (new rabbitmq feature)
ruby examples/mq/ack.rb        # using ack
ruby examples/mq/pop.rb        # pop off messages one at a time

ruby examples/mq/hashtable.rb  # simple async rpc layer
ruby examples/mq/primes.rb 4   # parallelized prime number generation
ruby examples/mq/logger.rb     # simple logging api

For high level API documentation see MQ class. For more details into the lower level AMQP client API, run the simple client example:

ruby examples/amqp/simple.rb   # low-level AMQP api
ruby examples/mq/internal.rb   # low-level Queue/Exchange api

Or refer to protocol/doc.txt, which enumerates packets sent between a server and client during a typical session, in both binary and decoded formats.

How to use AMQP gem with Ruby on Rails, Merb, Sinatra and other web frameworks

To use AMQP gem from web applications, you would need to have EventMachine reactor running. If you use Thin, you are all set: Thin uses EventMachine under the hood.

With other web servers, you need to start EventMachine reactor in it's own thread like this:

Thread.new { EM.run }

because otherwise EventMachine will block current thread. Then connect to AMQP broker:

AMQP.connect(:host => "localhost", :user => "guest", :pass => "guest", :vhost => "/")

In a Ruby on Rails app, probably the best place for this code is initializer (like config/initializers/amqp.rb). For Merb apps, it is config/init.rb. For Sinatra and pure Rack applications, place it next to other configuration code.

If you want to integrate AMQP with Thin or another EventMachine-based software which already runs an event loop, you might want to use following code:

EM.next_tick { AMQP.connect(...) }

So in case the reactor isn't running yet (which seems to be the case with Ruby on Rails 3.x and Thin combination), it won't fail, but wait when the reactor is started (see issue #21).

Same separate thread technique can be used to make EventMachine play nicely with other libraries that would block current thread (like File::Tail).

Contributions

All the dependencies are specified in Gemfile, so if you have Bundler, you can just run bundle install.

The lib/amqp/spec.rb file is generated automatically based on the AMQP specification. To generate it:

rake codegen

For running specs, use rake spec.

Credits and more information

The Original Code is tmm1/amqp.
The Initial Developer of the Original Code is Aman Gupta.

Current maintainer: Jakub Stastny aka botanicus.

This project was inspired by py-amqplib, rabbitmq, qpid and rubbyt. Special thanks to Dmitriy Samovskiy, Ben Hood and Tony Garnock-Jones.

AMQP brokers

RabbitMQ (Rabbit Technologies, Erlang/OTP, MPL)
OpenAMQ (iMatix, C, GPL2)
ActiveMQ (Apache Foundation, Java, Apache2)

AMQP resources

Steve Vinoski explains AMQP in his column, Towards Integration
John O'Hara on the history of AMQP
Dmitriy's presentation on RabbitMQ/AMQP
ZeroMQ's analysis of the messaging technology market
Pieter Hintjens's background to AMQP
Barry Pederson's py-amqplib
Ben Hood on writing an AMQP client
Dmitriy Samovskiy introduces Ruby + QPid + RabbitMQ
Ben Hood's as3-amqp (two, three)
RabbitMQ's AMQP protocol code generator
Erlang Exchange presentation on the implementation of RabbitMQ (and on the LShift blog)
Jonathan Conway's series on RabbitMQ and using it with Ruby and Merb: One, Two, Three, Four
Open Enterprise's series on messaging middleware and AMQP: Part 1, Part 2, Part 3

ivanvanderbyl-amqp

Development

Runtime