[occi-wg] OCCI MC - State Machine Diagram
Edmonds, AndrewX
andrewx.edmonds at intel.com
Mon Apr 20 07:47:16 CDT 2009
Then conceptually, how do we recover from an error state if we've exited? Also if we want to support error state recovery, should the state model reflect this?
-----Original Message-----
From: Thijs.Metsch at Sun.COM [mailto:Thijs.Metsch at Sun.COM]
Sent: 20 April 2009 13:42
To: Sam Johnston
Cc: Edmonds, AndrewX; occi-wg at ogf.org; Molino, VictorX M
Subject: Re: [occi-wg] OCCI MC - State Machine Diagram
As I stated before maybe we an add another exit-point instead of a real
state.
Cheers,
-Thijs
On Mon, 2009-04-20 at 14:39 +0200, Sam Johnston wrote:
> On Mon, Apr 20, 2009 at 2:29 PM, Edmonds, AndrewX
> <andrewx.edmonds at intel.com> wrote:
> I updated the state model (attached) to include an error
> state. Couldn’t see how to delete attachments so maybe someone
> here has better luck? I also began to add identifiers to each
> process transition but the diagram started to become cluttered
> so left them out.
>
>
> I would suggest that it's better to keep this clean (though I'm
> impressed that you got as far as you did!). You can reach an error
> state from anywhere - if a machine is found to be corrupt even while
> stopped then a STOPPED->ERROR transition makes sense for example.
>
> Sam
>
> From: occi-wg-bounces at ogf.org [mailto:occi-wg-bounces at ogf.org]
> On Behalf Of Sam Johnston
> Sent: 20 April 2009 11:56
> To: Tino Vazquez
> Cc: occi-wg at ogf.org; Molino, VictorX M; Thijs Metsch
>
>
> Subject: Re: [occi-wg] OCCI MC - State Machine Diagram
>
>
> 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
> State
>
>
> Transitions
>
>
> Description
>
>
> aborting
>
>
> aborted
>
>
> The resource
> encountered an error
> and is aborting
>
>
> aborted
>
>
> n/a
>
>
> The resource
> encountered an error
> and has aborted
>
>
> active
>
>
> pause, restart,
> stop, suspend
>
>
> The resource is
> active
>
>
> resuming
>
>
> aborting, active
>
>
> The resource is
> becoming active and
> restoring state
>
>
> pausing
>
>
> aborting, paused
>
>
> The resource is
> preparing to refuse
> new requests
>
>
> paused
>
>
> aborting, resume
>
>
> The resource is
> refusing new
> requests
>
>
> starting
>
>
> aborting, active
>
>
> The resource is
> becoming active
>
>
> stopped
>
>
> start
>
>
> The resource is
> inactive and has no
> saved state
>
>
> stopping
>
>
> stopped, aborting
>
>
> The resource is
> becoming inactive
> and destroying state
>
>
> suspended
>
>
> resume, stop
>
>
> The resource is
> inactive and has
> saved state
>
>
>
> Note: Stable states and user transitions in bold.
>
>
>
>
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--
Thijs Metsch Tel: +49 (0)941 3075-122 (x60122)
http://blogs.sun.com/intheclouds
Software Engineer Grid Computing
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