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.
--
Regards
Heidi Eckhart
Software Engineer
IBM Linux Technology Center - Open Hypervisor