On 06/25/2013 07:33 AM, sanvasky_poche wrote:
hello Apache Qpid developers. Now i am working on Qpid Cpp broker. I am trying to know the broker control flow of execution of programs while running and while shutdown the broker. Can any body help me out please ..
I assume you are asking about the control of the flow of messages in and out of the broker(?).
On the publisher side, the broker will stop confirming messages that when the queue they are enqueued into exceeds some limit. This doesn't directly stop the flow but it gives the clients a means of regulating the rate at which they publish. If the client has a window of in-doubt (unconfirmed) messages and blocks when that window is full, then this works well to throttle the producers. This is the case for the qpid::messaging clients for example. Eventually the broker must protect itself if the queue depth keeps growing and that can be done by simply refusing any further messages after a given point. See http://qpid.apache.org/books/0.20/AMQP-Messaging-Broker-CPP-Book/html/producer-flow-control.html for more detail.
On the consumer side, the consumer can control the number of pre-fetched messages through setting credit. In the qpid::messaging API this is done by setting the capacity on senders or receivers. See http://qpid.apache.org/books/0.20/Programming-In-Apache-Qpid/html/prefetch.html
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