[Caml-list] [ANN] Netamqp, a client for AMQP-0-9-1

[Caml-list] [ANN] Netamqp, a client for AMQP-0-9-1

[Gerd Stolpmann]

Hi,

the ocaml team at Mylife is proud to release another library to the
public: Netamqp is a client of the AMQP-0-9-1 protocol which is used to
talk to message queue servers. Netamqp is an independent implementation
of such a client, and not simply a wrapper around a C library.  Netamqp
has been tested against RabbitMQ.

Message queues are another way of establishing communication paths
between independent processes. The nice aspect about this architecture
is that message queues form a store-and-forward network: Each
participant is only a client of the central store, and is not required
to permanently check for the arrival of input. Messages arriving when
the client cannot pay attention are preserved in the queue. This makes
message queue networks very robust and easy to operate. The downside is
that there is a single point of failure, namely the queue server.

Messages are just strings of any length. AMQP does not attempt to define
a serialization format.

The Netamqp client allows synchronous and asynchronous message
processing, the latter with the help of Ocamlnet's event loop.

The homepage is at: http://oss.wink.com/netamqp/. See there for download
links, and the online manual.

There is a GODI package for Ocaml 3.12: godi-netamqp.

Gerd
-- 
------------------------------------------------------------
Gerd Stolpmann, Bad Nauheimer Str.3, 64289 Darmstadt,Germany 
gerd@gerd-stolpmann.de          http://www.gerd-stolpmann.de
Phone: +49-6151-153855                  Fax: +49-6151-997714
------------------------------------------------------------

Re: [Caml-list] [ANN] Netamqp, a client for AMQP-0-9-1

[Richard W.M. Jones]

On Mon, Mar 28, 2011 at 04:03:09PM +0200, Gerd Stolpmann wrote:
> the ocaml team at Mylife is proud to release another library to the
> public: Netamqp is a client of the AMQP-0-9-1 protocol which is used to
> talk to message queue servers. Netamqp is an independent implementation
> of such a client, and not simply a wrapper around a C library.  Netamqp
> has been tested against RabbitMQ.

Gerd, have you tried to interoperate with any other language?

I tried examples/t_sender.ml along with the following Python receiver
(all on the same RabbitMQ instance), but the Python code didn't appear
to see any messages at all.  I'm quite probably doing something stupid.

----------------------------------------------------------------------
#!/usr/bin/python

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(
        'localhost'))
channel = connection.channel()

channel.queue_declare(queue='test_xy')

def callback(ch, method, properties, body):
    print " [x] Received %r" % (body,)

channel.basic_consume(callback,
                      queue='test_xy',
                      no_ack=True)

print ' [*] Waiting for messages. To exit press CTRL+C'
channel.start_consuming()
----------------------------------------------------------------------

Rich.

-- 
Richard Jones
Red Hat

Re: [Caml-list] [ANN] Netamqp, a client for AMQP-0-9-1

[Gerd Stolpmann]

Am Montag, den 19.09.2011, 18:08 +0100 schrieb Richard W.M. Jones:
> On Mon, Mar 28, 2011 at 04:03:09PM +0200, Gerd Stolpmann wrote:
> > the ocaml team at Mylife is proud to release another library to the
> > public: Netamqp is a client of the AMQP-0-9-1 protocol which is used to
> > talk to message queue servers. Netamqp is an independent implementation
> > of such a client, and not simply a wrapper around a C library.  Netamqp
> > has been tested against RabbitMQ.
> 
> Gerd, have you tried to interoperate with any other language?

Well, this was developed for Mylife in a project where the sender was
written in Python. (I don't have access to this code anymore, though,
since I left Mylife.)

> I tried examples/t_sender.ml along with the following Python receiver
> (all on the same RabbitMQ instance), but the Python code didn't appear
> to see any messages at all.  I'm quite probably doing something stupid.

What's missing here is that you need to bind the queue to an exchange.
Remember that t_sender only sends the message to the exchange amq.direct
with a routing key of test_xy_routing_key. It does not send the message
to test_xy directly (which is not possible). Without binding, the
exchange just drops unroutable messages.

Don't know exactly how to bind in Python, but watch out for a method
queue_bind.

Gerd


> 
> ----------------------------------------------------------------------
> #!/usr/bin/python
> 
> import pika
> 
> connection = pika.BlockingConnection(pika.ConnectionParameters(
>         'localhost'))
> channel = connection.channel()
> 
> channel.queue_declare(queue='test_xy')
> 
> def callback(ch, method, properties, body):
>     print " [x] Received %r" % (body,)
> 
> channel.basic_consume(callback,
>                       queue='test_xy',
>                       no_ack=True)
> 
> print ' [*] Waiting for messages. To exit press CTRL+C'
> channel.start_consuming()
> ----------------------------------------------------------------------
> 
> Rich.
> 
> -- 
> Richard Jones
> Red Hat
> 

-- 
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
Creator of GODI and camlcity.org.
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
*** Searching for new projects! Need consulting for system
*** programming in Ocaml? Gerd Stolpmann can help you.
------------------------------------------------------------

Re: [Caml-list] [ANN] Netamqp, a client for AMQP-0-9-1

[Richard W.M. Jones]

On Tue, Sep 20, 2011 at 12:26:15PM +0200, Gerd Stolpmann wrote:
> Am Montag, den 19.09.2011, 18:08 +0100 schrieb Richard W.M. Jones:
> > On Mon, Mar 28, 2011 at 04:03:09PM +0200, Gerd Stolpmann wrote:
> > > the ocaml team at Mylife is proud to release another library to the
> > > public: Netamqp is a client of the AMQP-0-9-1 protocol which is used to
> > > talk to message queue servers. Netamqp is an independent implementation
> > > of such a client, and not simply a wrapper around a C library.  Netamqp
> > > has been tested against RabbitMQ.
> > 
> > Gerd, have you tried to interoperate with any other language?
> 
> Well, this was developed for Mylife in a project where the sender was
> written in Python. (I don't have access to this code anymore, though,
> since I left Mylife.)
> 
> > I tried examples/t_sender.ml along with the following Python receiver
> > (all on the same RabbitMQ instance), but the Python code didn't appear
> > to see any messages at all.  I'm quite probably doing something stupid.
> 
> What's missing here is that you need to bind the queue to an exchange.
> Remember that t_sender only sends the message to the exchange amq.direct
> with a routing key of test_xy_routing_key. It does not send the message
> to test_xy directly (which is not possible). Without binding, the
> exchange just drops unroutable messages.
> 
> Don't know exactly how to bind in Python, but watch out for a method
> queue_bind.

Thanks, that works.  For future reference, below is the full
working receiver.

Rich.

----------------------------------------------------------------------
#!/usr/bin/python

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(
        'localhost'))
channel = connection.channel()

channel.queue_declare(queue='test_xy')

channel.queue_bind(exchange='amq.direct',
                   queue='test_xy',
                   routing_key='test_xy_routing_key')

def callback(ch, method, properties, body):
    print " [x] Received %r" % (body,)

channel.basic_consume(callback,
                      queue='test_xy',
                      no_ack=True)

print ' [*] Waiting for messages. To exit press CTRL+C'
channel.start_consuming()
----------------------------------------------------------------------

-- 
Richard Jones
Red Hat