launchpad-dev team mailing list archive

[Julian Edwards <julian.edwards@xxxxxxxxxxxxx>]

On Thursday 08 October 2009 22:21:20 Aaron Bentley wrote:
> I don't think so.  It's no coincidence that Muharem presented a Job
> system as a use case at the Epic.  Polling will never be as responsive
> or efficient as messaging.

I disagree with the word "never".

I am a huge fan of messaging systems and I have a lot of experience with them 
and also with polling-based solutions.

Consider the situation where you have several updates causing diff requests on 
the same branch.  You're only interested in the last change; with a message 
for each diff request, calculating the diffs in-between is a waste as you will 
throw them away with subsequent diff processing.  If you were to periodically 
poll, you would see only the most recent change and work with that.

This is a slightly contrived example but you get my drift.

Basically, there is a trade-off between responsiveness and efficient 
processing.