canonical-ci-engineering team mailing list archive

[Thomi Richards <thomi.richards@xxxxxxxxxxxxx>]

On Mon, May 18, 2015 at 9:12 AM, Evan Dandrea <evan.dandrea@xxxxxxxxxxxxx>
wrote:

> What of our needs
> would pubsubhubbub address that a Rabbit fanout exchange wouldn't?
>

The two main differences I see are:

1) Rabbit queues rely on a central, well-known point of contact that has to
be pre-negotiated amongst the services. PSHB allows publishers to nominate
their own hubs for distribution.

The other difference is in the aggregation from hub -> consumer (or from
rabbit exchange -> consumer):

   - Rabbit fanout exchanges are still queues. If the producer produces 100
   messages, and the consumer consumes one message, the consumer still has 99
   messages (all together now: "99 bottles of beer on the wall, 99 bottles of
   beer on the wall, take one down, pass it around....")
   - PSHB hubs will aggregate multiple new resources in a single message
   for consumers.


Rabbit is much more suited to command payloads, where each payload has to
be processed separately. PSHB is more suited to data, where consumers want
to know 'everything that happened since I last asked' (think atom feeds).

Just to be clear: I'm not suggesting we use this right now for any
particular project - I just wanted to put it on everyone's radar :D

Cheers,
-- 
Thomi Richards
thomi.richards@xxxxxxxxxxxxx