[occi-wg] OCCI MC - State Machine Diagram

[Edmonds, AndrewX]

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.

Andy


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<http://forge.ogf.org/sf/wiki/do/viewPage/projects.occi-wg/wiki/Registries> (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<mailto: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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