Defining callback function for methods called from python (pika library)

Hello,

I am trying to use the "py.*" functionality in matlab.

I am calling the pika library to connect and consume from a RabbitMQ Server.

While the following code does work:

channel = connection.channel();

channel.queue_declare(queue='hello');

channel.basic_publish(exchange='exchangename', routing_key='key.name', body='somemessage',properties=py.pika.BasicProperties(reply_to='hello'))

connection.close();

The other part does not work:

connection_r = py.pika.BlockingConnection(py.pika.ConnectionParameters(host='localhost'));

channel_r = connection_r.channel();

channel_r.queue_declare(queue='hello');

channel_r.basic_consume(queue='hello', auto_ack=true,on_message_callback= @Callbackfunction);

channel_r.start_consuming()

I get erros saying that i can't send MATLAB functions in to the python env. And i also can't just define the functions there because it does not work.

Is there anyway to make this work ? to connect Pika's basic_consume method to a matlab callback ?

Thanks.

Answer 1

[Abhijeet]

Hi Ran,

I can understand that you want to use a callback function written in MATLAB and use it inside ‘basic_consume’ function defined in pika library. In order to use MATLAB callback function inside ‘basic_consume’ you can refer the following steps: -

1. You can write a MATLAB script which defines the callback function.
2. Inside a python script write a callback function that calls MATLAB using ‘MATLAB Engine API for Python’. Please refer to the following example code :-

import matlab.engine

def python_callback( ):
   eng = matlab.engine.start_matlab()
   eng.Callbackfunction(nargout=0)
   eng.quit()

3. Use the callback written inside python script as argument for ‘basic_consume’ function.

To learn more about the ‘MATLAB Engine API for Python’ please refer to the following documentation: https://www.mathworks.com/help/matlab/matlab_external/get-started-with-matlab-engine-for-python.html