Another possible implementation is through supervisord:

http://supervisord.org/manual/current/api.process-control.html#api.process-control.supervisor-sendremotecommevent

http://supervisord.org/manual/current/events.html#event_listeners_and_event_notifications

log to the queue:

http://fallenpegasus.livejournal.com/852077.html

http://code.flickr.com/blog/2008/09/26/flickr-engineers-do-it-offline/

http://github.com/robey/kestrel/tree/master

http://robey.livejournal.com/53832.html

http://github.com/nkallen/cache-money/tree/master

http://pear.php.net/pepr/pepr-proposal-show.php?id=596

http://www.oddments.org/?p=50

https://www.dropr.org/

PHP gearman extension:

https://launchpad.net/gearman-php-ext

Also check out this for API design of pluggable job backends:

http://www.scribd.com/doc/6134982/Starling-Workling-Simple-Distributed-Background-Jobs-With-Twitters-Queuing-System-Presentation



and these for potential job backends:

http://github.com/starling/starling

http://rubypond.com/articles/2008/07/17/the-complete-guide-to-setting-up-starling/

http://blog.kovyrin.net/2008/10/30/activemq-ruby-stomp-client-how-to-process-elements-one-by-one/

Important features:



- client can lock a queue task for a set period of time while processing it

- if a lock expires, other queue clients can pick up the task

- clients can delete tasks when they're done

Another possible backend:

http://www.danga.com/gearman/

http://decafbad.com/blog/2008/07/04/queue-everything-and-delight-everyone

push object update notifications (like in kronolith) here instead of 
doing them in-line. have api calls for picking up object updates 
(listeners essentially). also have api calls for whether an app does 
update triggers for a given content-type.



default backend - Horde_Queue_Unqueue (or immediate?) that processes 
tasks immediately upon being added to the queue. Not great for 
performance, but no worse than the current inline tasks, and provides 
an easy path for small sites that don't need to set up a queue daemon.



sql backend along with SQS



monitor the daemon with supervisord?



http://q4m.31tools.com/