[occi-wg] OCCI MC - State Machine Diagram

Sam Johnston samj at samj.net
Mon Apr 20 05:56:30 CDT 2009

Hi Tino,

A lot of this is covered in the state
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

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.

Extensions State control StateTransitionsDescription abortingabortedThe
resource encountered an error and is aborting *aborted*n/aThe resource
encountered an error and has aborted *active**pause*, *restart*, *stop*, *
suspend*The resource is active resumingaborting, activeThe resource is
becoming active and restoring state pausingaborting, pausedThe resource is
preparing to refuse new requests *paused*aborting, *resume*The resource is
refusing new requests startingaborting, activeThe resource is becoming
active *stopped**start*The resource is inactive and has no saved state
stoppingstopped, abortingThe resource is becoming inactive and destroying
state *suspended**resume*, *stop*The resource is inactive and has saved

*Note*: Stable states and user transitions in *bold*.
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