[occi-wg] OCCI MC - State Machine Diagram

Tino Vazquez tinova at fdi.ucm.es
Mon Apr 20 07:46:05 CDT 2009

Hi Sam,

Thanks for pointing out the registry, I missed it somehow. I like the
extensions idea, quite neat.

Also, I'm happy with a new "NEW" state and having "ABORTED" as the
failed state, although I'm not sure if we should use this for both 1)
the case that the machine has crashed due to some error and 2) the
user cancels the machine.


On Mon, Apr 20, 2009 at 12:56 PM, Sam Johnston <samj at samj.net> wrote:
> Hi Tino,
> A lot of this is covered in the state registry (which I'll copy below for
> you) but comments inline nonetheless.
> On Mon, Apr 20, 2009 at 12:35 PM, Tino Vazquez <tinova at fdi.ucm.es> wrote:
>> Howdy everyone,
>> Excellent thread. My three cents:
>> 1) I think we should define clearly the semantics of the states. for
>> instance, what is the difference between STOPPED and SUSPENDED? Is it
>> that with SUSPENDED the state is saved and not with STOPPED?
> Yes, it's exactly that. From the state registry: STOPPED = "The resource is
> inactive and has no saved state" and SUSPENDED="The resource is inactive and
> has saved state"
>> 2) I really think we need an entry state like "PENDING" or "DEFINED".
>> It will help in implementation relying on a best-effort scheduler to
>> match VMs and hosts, like EC2 does. This will be the state where
>> machines will wait for a host to be available to run on. Also, I don't
>> really think that a machine entering its life cycle in SUSPENDED state
>> is a good idea.
> I tend to agree, but I'd like the terminology to be completely
> unambiguous... something like "NEW" [for this AS].
>> 3) +1 to the "CRASHED", "ERROR" or "FAILED" state.
> ABORT[ING|ED] = "The resource encountered an error and is aborting/has
> aborted".
>> What do you think?
> Some of these transitions take a while so some way of indicating progress
> (especially interesting for long tasks like live migrations) would be
> useful. Would prefer a mechanism that worked universally for the API.
> Sam
> Extensions
> State control
> StateTransitionsDescription
> abortingabortedThe resource encountered an error and is aborting
> abortedn/aThe resource encountered an error and has aborted
> activepause, restart, stop, suspendThe resource is active
> resumingaborting, activeThe resource is becoming active and restoring state
> pausingaborting, pausedThe resource is preparing to refuse new requests
> pausedaborting, resumeThe resource is refusing new requests
> startingaborting, activeThe resource is becoming active
> stoppedstartThe resource is inactive and has no saved state
> stoppingstopped, abortingThe resource is becoming inactive and destroying
> state
> suspendedresume, stopThe resource is inactive and has saved state
> Note: Stable states and user transitions in bold.

Constantino Vázquez, Grid Technology Engineer/Researcher:
DSA Research Group: http://dsa-research.org
Globus GridWay Metascheduler: http://www.GridWay.org
OpenNebula Virtual Infrastructure Engine: http://www.OpenNebula.org

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