[rabbitmq-discuss] Queue with message dropping

[Matwey V. Kornilov]

Hi,

Let me imagine that I have a queue and an exchange bound with each 
other. They implements pub/sub pattern, so the queue is private, only 
one consumer consumes from the given queue.

Let every message be somehow marked in headers with a special tag. I 
would like to get the following behaviour. If we have the message with 
the tag "Tag1" in the queue, and It is not consumed yet, and if there is 
new message with the tag "Tag1" coming from the exchange to the end of 
the queue, then I want the first message with the tag "Tag1" be 
unconditionally dropped from the queue and other messages left untouched.

The idea behind this is that I have a flow of events coming through the 
broker, and consumers have to act somehow on the events receive. But 
events may 'cancel' each other, and If I know that there is the most 
recent event, then I don't want to pay attention to obsoleted and 
unprocessed information, which may be still in message queue.