Puka - the opinionated RabbitMQ client

Puka is yet-another Python client library for RabbitMQ. But as opposed to similar libraries, it does not try to expose a generic AMQP API. Instead, it takes an opinionated view on how the user should interact with RabbitMQ.

Puka is simple

Puka exposes a simple, easy to understand API. Take a look at the publisher example:

import puka

client = puka.Client("amqp://localhost/")

promise = client.connect()
client.wait(promise)

promise = client.queue_declare(queue='test')
client.wait(promise)

promise = client.basic_publish(exchange='', routing_key='test',
                              body='Hello world!')
client.wait(promise)

Puka is asynchronous

Puka is fully asynchronous. Although, as you can see in example above, it can behave synchronously. That's especially useful for simple tasks when you don't want to introduce callbacks.

Here's the same code written in an asynchronous way:

import puka

def on_connection(promise, result):
    client.queue_declare(queue='test', callback=on_queue_declare)

def on_queue_declare(promise, result):
    client.basic_publish(exchange='', routing_key='test',
                         body="Hello world!",
                         callback=on_basic_publish)

def on_basic_publish(promise, result):
    print " [*] Message sent"
    client.loop_break()

client = puka.Client("amqp://localhost/")
client.connect(callback=on_connection)
client.loop()

You can mix synchronous and asynchronous programming styles if you want to.

Puka never blocks

In the pure asynchronous programming style Puka never blocks your program waiting for network. However it is your responsibility to notify when new data is available on the network socket. To allow that Puka allows you to access the raw socket descriptor. With that in hand you can construct your own event loop. Here's an the event loop that may replace wait_for_any from previous example:

 fd = client.fileno()
 while True:
    client.run_any_callbacks()

    r, w, e = select.select([fd],
                            [fd] if client.needs_write() else [],
                            [fd])
    if r or e:
        client.on_read()
    if w:
        client.on_write()

Puka is fast

Puka is asynchronous and has no trouble in handling many requests at a time. This can be exploited to achieve a degree of parallelism. For example, this snippet creates 1000 queues in parallel:

promises = [client.queue_declare(queue='a%04i' % i) for i in range(1000)]
for promise in promises:
    client.wait(promise)

Puka also has a nicely optimized AMQP codec, but don't expect miracles

• it can't go faster than Python.

Puka is sensible

Puka does expose only a sensible subset of AMQP, as judged by the author.

The major differences between Puka and normal AMQP libraries include:

• Puka doesn't expose AMQP channels to the users.
• Puka treats basic_publish as a synchronous method. You can wait on it and make sure that your data is delivered. Alternatively, you may ignore the promise and treat it as an asynchronous command.
• Puka tries to cope with the AMQP exceptions and expose them to the user in a predictable way. Unlike other libraries it's possible (and recommended!) to recover from AMQP errors.

Puka is experimental

Puka is a side project, written mostly to prove if it is possible to create a reasonable API on top of the AMQP protocol.

I like it! Show me more!

The best examples to start with are in the rabbitmq-tutorials repo.

More code can be found in the ./examples directory. Some interesting bits:

• ./examples/send.py: sends one message
• ./examples/receive_one.py: receives one message
• ./examples/stress_amqp_consume.py: a script used to benchmark the throughput of the server

There is also a bunch of fairly complicated examples hidden in the tests (see the ./tests directory).

I want to install Puka

Puka works with Python 2.6 and 2.7.

You can install Puka system-wide using pip:

sudo pip install puka

Alternatively to install it in the virtualenv local environment:

 virtualenv my_venv
 pip -E my_venv install puka

Or if you need the code from trunk:

sudo pip install -e git+http://github.com/majek/puka.git#egg=puka

I want to run the examples

Great. Make sure you have rabbitmq server installed and follow this steps:

git clone https://github.com/majek/puka.git
cd puka
make
cd examples

Now you're ready to run the examples, start with:

python send.py

I want to see the API documentation

The easiest way to get started is to take a look at the examples and tweak them to your needs. Detailed documentation doesn't exist now. If it existed it would live here:

http://majek.github.com/puka/