[occi-wg] Nouns and Verbs (was: Syntax of OCCI API) - state model

Andre Merzky andre at merzky.net
Fri Apr 17 09:21:20 CDT 2009

Quoting [Lars Larsson] (Apr 17 2009):
> On Fri, 17 Apr 2009, Ignacio Martin Llorente wrote:
> > We do not need "migrated", that is an internal operation that can not
> > be requested using a Cloud API
> I fully agree with Ignacio.
> I think there is a difference between the set of states that a 
> VM can be in, and the set of states that may be set using the 
> API. The first set may be larger and include informational 
> states such as "being migrated" or "being copied", but that does 
> not mean that the user can actively request that a VM should be 
> migrated.

Yes, I agree with that: active versus informational states.
Again, other state models in OGF represent such information
as substates, e.g. 'Migrating' might be expressed as a
substate of 'Running'.  I am not saying this is how this
group should do state modeling, just for information...

> I suggest that we use the states shown at page 25 in "CIM System 
> Virtualization White Paper" by the DMTF (DSP2013), available 
> here:
>  	http://www.dmtf.org/standards/published_documents/DSP2013_1.0.0.pdf

That is an interesting model - it seems a lot of people have
been thinking hard about that :-)   I like it...

To play the devils advocate though:

  - Is that state model suitable for our use cases?  It
    seems to allow for quite a large number of transissions,
    but is missing the 'Initial -> Suspended' transition
    which has been discussed on this list earlier.

  - The design seems to have been motivated by physical
    states rather than logical states (the power state notes
    are an artifact of that I guess?).  Are the states
    applicable to our use cases?

  - Do we need a distinction between 'VS State' and 'Enabled
    State'?  The document says: " the EnabledState property
    represents the virtual system’s state" - so, what is the
    difference to VS state, which is, I take, also the
    virtual system state?  The document does not offer a
    better definition/distinction AFICS.

> Displaying extra information, such as "being migrated" or "being 
> copied" is up to the infrastructure provider to optionally add 
> to the description of the state that is reported via monitoring.


Best, Andre.

Nothing is ever easy.

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