Re: [Xen-API] New API Document and C Bindings

[Gareth S Bestor <bestor@xxxxxxxxxx>]

Yup. Arbitrary domains serving up 'resources' for arbitrary other domains would not map to a hierarchy, not without some strict limitations that would probably be rather messy for Xen to enforce.

This potential functionality does not map particularly well to today's DMTF model either, but that's not Xen-API's problem...

- Gareth

Dr. Gareth S. Bestor
IBM Linux Technology Center
M/S DES2-01
15300 SW Koll Parkway, Beaverton, OR 97006
503-578-3186, T/L 775-3186, Fax 503-578-3186

"Daniel P. Berrange" <berrange@xxxxxxxxxx>

"Daniel P. Berrange" <berrange@xxxxxxxxxx>

09/15/06 08:00 AM

Please respond to
"Daniel P. Berrange" <berrange@xxxxxxxxxx>

To	Ronald Perez/Watson/IBM@IBMUS
cc	Gareth S Bestor/Beaverton/IBM@IBMUS, Xen-API <xen-api@xxxxxxxxxxxxxxxxxxx>, xen-api-bounces@xxxxxxxxxxxxxxxxxxx
Subject	Re: [Xen-API] New API Document and C Bindings

On Fri, Sep 15, 2006 at 10:48:53AM -0400, Ronald Perez wrote:
> "Daniel P. Berrange" <berrange@xxxxxxxxxx> wrote on 09/15/2006 10:32:33 
> AM:
> > 
> > We are primarily talking about how to express things in the Xen API - 
> this
> > does not have to match how its expressed in CIM (provided we expose 
> enough
> > information in Xen API for CIM to doing a suitable re-mapping). For 
> example
> > in the Xen API we can express all domains the same way, but that doesn't
> > stop CIM expressing Domain-0 in a special Host class, seprate from other
> > guest VMs if that's appropriate for the CIM model.
> > 
> > Dan.
> 
> Thanks. So if John's "class hierarchy" were really a recursive 
> representation (as mentioned previously), that would be equivalent to your 
> "overlapping sets"? e.g., host_CPUs == VCPUs on a domU.

No they are not equivalent. There are scenarios you can represent with
overlapping sets which you can't represent in a hierarchy.  Consider
three sets  A, B, C.  A overlaps with B, B overlaps with C, and C overlaps
with A - there's no way to represent that as a hierarchy - hierarchies
can only represent directed, a-cyclic graphs - overlapping sets are 
non-directional cyclic graphs.

> How do you envision capabilities being represented? By the presence or 
> absence of a field/feature/method or a bitmap or ???

A set of flags perhaps. Depending on the type of capability was want to
represent, they're not all going to be associated directly with a domain.
Some like lifecycle states may be scoped to a domain object. Others
may be associated with sub-objects - for example a domain having privileged
access to a piece of hardware may be flags on their hardware specific object.

Dan.
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