python stomp从activemq接收消息数

Question

Is it possible to receive only a number of messages from activemq.

Let say I need to receive only 100 messages from queue, is it possible.

I am using message listener method, is there any other method to receive messages.

example code snippet:

queue_messages = []

class SampleListener(object):
    def on_message(self, headers, msg):
        queue_messages.append(msg)
def read_messages():
    queue_connection = stomp.Connection([(activemq_host, int(activemq_port))])
    queue_connection.start()
    queue_connection.connect('admin', 'admin')
    queue_connection.set_listener('SampleListener', SampleListener())
    queue_connection.subscribe(destination=activemq_input_q, id=1, ack='auto')
    time.sleep(1)
    queue_connection.disconnect()

read_messages()

Answer 1

Why don't you share your problem rather than the solution in your mind? Chances are the problem might not be a problem as you think or there can be better solutions.

To answer your question, yes you can. For ActiveMQ case, you can add extra header like {'activemq.prefetchSize':100}, ans set ack='client', when you subscribe the queue. But you do not acknowledge the messages at all. The consequence is you will not receive any more messages than 100.

It is a awkward solution I must say. Your code will end up with consuming the first 100 messages in the queue and that's it. You can apparently disconnect and resubscribe the same queue to receive the next 100 messages.

Answer 2

when ack='client' and i don't acknowledge the message on on_message event, when actually the acknowledgement will be sent to the server, will it send the acknowledgement on successful disconnect.

Also, if i abruptly kill the script, will be acknowledgement be still sent and will i miss the messages