[SAGA-RG] SAGA Job State Model

[Andre Merzky]

Quoting [Ole Christian Weidner] (Mar 22 2010):
> 
> Aloha,
> 
> what was the reason again *not* to have a "pending" state in the
> saga job model? 

The decision on what states are on the top level of the SAGA state
model was based on the operations available in the API: only those
states got added which were explicitely reachable via some API
method.  

A 'Pending' state cannot be reached (or left, depending on
semantics) by any SAGA API call, thus that is only available as
state detail, not as top level state.


> I'm implementing the third job adaptor (gLite
> CREAM) for saga and again, I don't know if I should map gLite's
> "pending" state to saga::job::New or saga::job::Running.

It should go to Running (as almost all substates IMHO).  New is
usually defined so that a job does not yet have a backend
representation.  In Pending states however, most middleware do
already maintain job state.


> Most of the middleware API's out there come with a plethora of
> states (e.g. gLite: 11), but most of them map naturally map to one
> of the saga job model's states. "Pending" is a state pretty much
> used by everyone (Condor, PBS, LSF, Globus, gLite, GridSAM) and it
> really doesn't map to saga's model. IMHO it's a major design flaw
> - how could this fall through the sieve? Or is there a  reason
> behind this?

See above.  As you say, there is a plethora of states, and many are
important for specific use cases.  Other states have been candidates
for SAGA, such as StageIn and StageOut, or Hold, for all of which
exist interesting use cases.  But again: it did not seem very useful
to expose states on the top level which cannot be reached via API
calls - they are then only useful for informational purposes.  As
such, they are still available in the state details.

Also, as a last point: the more states we add to SAGA, the more
difficult it is to map to a specific backend state model (DRMAA,
AWS, local, ssh and BES come to my mind which do not have a Pending,
for example).

Best, Andre.



> Cheers, Ole

-- Nothing is ever easy.