Re: [Libvirt-cim] [PATCH 0 of 2] [RFC] ComputerSystemModifiedIndication

Dan Smith wrote: > JG> Is there a mechanism for indications reporting errors, beyond > JG> CU_DEBUG'ing "help" and hoping to recover? > > I would expect that the answer will be that there isn't much that can > be done. A CU_DEBUG() indicating the issue is certainly required, but > I'm not sure what else we have. > CU_DEBUG() is the providers possibility to report an error. A mechanism to report a failure in the indication processing itself to the subscriber of the ComputerSystemModfiedIndication can not be done via the ComputerSystemModifiedIndication. This indication will only be thrown, if all went fine. So an indication in general is only reporting positive results - means, if the filter requirement is fulfilled, the indication is thrown. To monitor a failing indication processing an additional indication provider would be necessary. This one would then handle "please inform me, if something in the processing of the ComputerSystemModfiedIndication failed". So a client would need to subscribe 1) to the ComputerSystemModifiedIndication to get informed of the modification and 2) to the AlertIndication monitoring the indication processing to get informed of a failing processing.

> I tend to think that indications are mostly for convenience and > optimization, to avoid pinging the providers unnecessarily, in which > case an error wouldn't be catastrophic. Multiple clients monitoring a > single provider would use them to notice when the other makes a > change. > I absolutely agree. For now I would say, its more important to have the ComputerSystemModifiedIndication. But at a later point in time - an indication provider who reports processing failures could be added as a feature.