[Openstack] [metering] high-level design proposal

James R Penick penick at yahoo-inc.com
Tue May 22 20:35:40 UTC 2012


>>-> In addition to a signature, I think we would need a sequence number
>>to be embedded by the agent for each message sent, so that loss of
>>messages, or forgery of messages, can be detected by the collector and
>>further audit process.

>OK. We have a message id, but I assumed those would be used to eliminate
>duplicates so this sounds like something different or new. It implies
>that the agent knows its own id (not hard) and keeps up >with a sequence
>counter (more difficult, though not impossible).
>Did you have something in mind for how to implement that?
 

If we're submitting messages every given node with a predictable
frequency, we should be able to determine that a message was lost simply
by noting a gap in the timestamps. Also, if we're sending cumulative
statistics then the loss of a single message (or even a fair number of
them) shouldn't impact our ability to meter too much.

-James





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