launchpad-dev team mailing list archive

[Martin Pool <mbp@xxxxxxxxxxxxx>]

On 24 September 2010 23:27, Aaron Bentley <aaron@xxxxxxxxxxxxx> wrote:
> I'm really only interested in the practical distinction: stuff we have
> already considered and started to gather requirements for, and stuff
> that we haven't.

+1

> I think there's a theoretical distinction between imperative messages
> and informative messages.  Informative messages ("this branch tip has
> changed") don't imply that the sender expects any particular
> consequence, and are multicast-- all interested workers should consume
> the message.  Imperative messages ("run a scan job on this branch") do
> imply an expected consequence, and provide a point of coordination--
> only one worker should run the branch scan job, and that worker will
> consume the message.

Right.  I was wondering if Launchpad was going to (now, or later)
change to just sending "this branch tip changed" and then have the
recipients decide what to do with that.  For instance, we want to
update precalculated mp preview diffs when the branch changes.
Ideally, in a message system, the branch scanner wouldn't need to know
anything about that, only the job that's subscribed to those events.
If we want to take that direction perhaps it's better not considering
it only as a task dispatch system?

-- 
Martin