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Ruby AMQP 0.7 released!

· 4 min read
Jakub Stastny

I'm happy to announce that the AMQP 0.7 is released, as I promised in the previous blog post. So what are the changes?

When you install the AMQP gem, you'll see changes of the current version. (How did I do that? With changelog gem and a bit of gemspec magic.)

Callback for MQ#queue​

Synchronous API for Queue.Declare/Queue.Declare-Ok request/response was exposed via asynchronous callback:

channel = MQ.new
fanout  = channel.fanout(:task_fanout)
channel.queue(:tasks) do |queue, message_count, consumer_count|
  puts "Queue #{queue.name} declared!"
  puts "Message count: #{message_count}"
  puts "Consumer count: #{consumer_count}"
end

Auto-named queues & not rewritting of anonymous entities in MQ#queues and MQ#exchanges​

If a queue is declared with an empty name, the broker is supposed to generate random name. In previous versions of the Ruby AMQP this wasn't supported, because the synchronous API (waiting for Queue.Declare-Ok was missing). Not anymore:

channel = MQ.new
channel.queue("") do |queue|
  puts "Queue with name #{queue.name} declared!"
end

# OUTPUT: Queue with name amq.gen-PfCGdyBA4Sr4rkZg3IN3Kw== declared!

The same should apply for exchanges, but this isn't supported by the current version of RabbitMQ.

Also, in the previous AMQP versions, the MQ#queues, MQ#exchanges and similar was just a hash, hence if given entity was anonymous (the name was nil), and if the collection already included another anonymous instance, then the one which was already in the collection was rewritten.

Callback for MQ::Queue#bind​

MQ::Queue#bind can take a callback, as well as MQ#queue now can:

channel = MQ.new
fanout  = channel.fanout(:task_fanout)
channel.queue(:tasks).bind(fanout) do |queue|
  puts "Queue #{queue.name} was bound!"
end

AMQP URL​

Thanks to majek, author of the Puka AMQP client for Python, you can use URL instead of option hash as an argument for AMQP.connect and AMQP.start:

AMQP.start("amqps:/")

# Will resolve to: {vhost: "/", port: 5671, ssl: true}

AMQP.start("amqp://botanicus@localhost:1111/")

# Will resolve to: {user: "botanicus", vhost: "/", host: "localhost", port: 1111, ssl: false}

MQ::Exchange.default​

The default exchange is a direct exchange with an empty name where all the queues are automatically bound (and you can't bind there anything manually). Do not confuse the default exchange with amq.direct which is only a predefined direct exchange without any "magic" abilities).

Fail if an entity is re-declared with different options​

Rather than wait for the server, than if possible we let this fail on the client, so the user gets more descriptive error message:

channel = MQ.new
channel.queue(:tasks, auto_delete: true)
channel.queue(:tasks, auto_delete: false)

# Exception: There is already an instance called tasks with options

{:queue => :tasks, :nowait => true, :auto_delete => true},
you can't define the same instance with different options ({:queue => :tasks,
:nowait => true, :auto_delete => false})! (MQ::IncompatibleOptionsError)

Don't reconnect if the credentials are invalid​

AMQP reconnects automatically if the connection failed. It did try to reconnect even on an error like providing invalid credentials. I changed it to register the reconnect hook after the connection is actually established, so if for whatever reason the connection fails, it won't try to reconnect.

rSpec 2 specs​

This is still work in progress, you can check the spec/ directory. Huge thanks to arvicco and michaelklishin for their work on this!

Issues​

We closed nearly all issues at tmm1/amqp repository. Please do not report any further bugs there, use ruby-amqp/amqp instead.

Friendlier environment for contributors​

We use bundler now, so if you want to contribute or just run the tests, just clone the repo, run bundle install and voila, that's it! There's also bin/irb for easier debugging.

Speaking about them, I'd really want to thank all the contributors, their work really helped to get the AMQP gem where it is now. Since the beginning 22 people contributed to the project, and 5 of them have more than 5 commits. Check the CONTRIBUTORS file for more details!

Plans for AMQP 0.8​

The next 0.8 release will bring some major API changes: there won't be two separate constants MQ and AMQP, but only the second one. The MQ class will become AMQP::Channel, so we will be compliant with the official AMQP terminology and we also want to introduce support for AMQP 0.9.1 via the AMQ-Protocol gem.

Any comments, ideas? You're always welcome to drop by at Jabber MUC amqp-dev@conf.netlab.cz, and tell us what do you think!