[occi-wg] Semantics of OCCI API: nouns and verbs
richard.davies at elastichosts.com
Fri Apr 17 03:32:00 CDT 2009
> > 1) Return all properties for a single known object (e.g. a single server
> > with known UUID). I assume this is somehow does with category search?
> > 2) Return a list of all objects (possibly for a given type), without
> > their properties (since these might be expensive to read). For example,
> > simply list the UUIDs of all servers?
> Ok sorry I forgot to mention that this was actually a requirement I had
> not considered (that is the performance and scalability cost of
> unnecessarily calling on extensions).
> 1. Actually it's even easier than that. If you know a UUID you can just
> GET <entrypoint>/<uuid> and you'll get the lot. Given categories can be
> arbitrarily large I'd suggest that they also be sparse.
That's good and simple.
> 2. By default we should just return just the basic content that's already
> in the database... so not bothering the performance monitor counters or
> asking the billing system to sum up usage (we have to hit the database
> anyway so this is no cost).
You may be overestimating how much is in the database (in our case at
least!). To avoid any risk of inconsistency, we typically don't cache any
server attributes on the central management servers where these are best
mastered on the virtualization hosts themselves. That includes things like
server titles, memory sizes, etc, etc. Pretty much just the UUIDs and which
hosts they're on is permanently remembered centrally.
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