Dependencies

Scott James Remnant scott at netsplit.com
Sun Oct 8 15:55:08 BST 2006


On Sat, 2006-10-07 at 10:17 -0500, Jerry Haltom wrote:

> > Also, I'd like a pointer to any discussion about conditional use cases.  Is 
> > there any mechanism for supporting the case where a service CAN use another 
> > service, but doesn't require it?  This may be an difficult problem to solve 
> > in an indeterminate, event-driven system like Upstart, but I'd like to know 
> > if anybody has given it any thought.  An example of this is a printing 
> > subsystem, where printers are connected both locally and remotely.  In this 
> > case, the Cups service may be triggered when a USB printer is detected, and 
> > when the network comes up.  How is this to be handled?  Do we start Cups when 
> > it gets a USB event, and then restart it when the network comes up?
> 
> Cups is a hard one. I'd say it should either watch the network on it's
> own and use HAL. Or accept a signal telling it to rescan everything, in
> response to an upstart event.
> 
"OR" events are easy, just list them in the job definition:

  on network
  on local-printer

CUPS should then use HAL to obtain the list of printers, and be updated
when new ones are inserted/removed.

Scott
-- 
Have you ever, ever felt like this?
Had strange things happen?  Are you going round the twist?
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