UWS POST PHASE=RUN

[Matthew Graham]

Hi,

On Nov 5, 2014, at 7:53 AM, Walter Landry wrote:

> Dave Morris <dave.morris at metagrid.co.uk> wrote:
>> On 2014-11-03 12:29, Paul Harrison wrote:
>>> The intention was that the parameters could be changed at any time up
>>> until the job was in the executing state (so a  QUEUED job can have
>>> its parameter values changed, but a job in any of the “terminal”
>>> states cannot)  - I will try to make this more explicit in the 1.1
>>> draft.
>> 
>> On 2014-11-04 18:16, Walter Landry wrote:
>>> Why do allow modification of parameters?  All of the queuing systems
>>> that I have worked with in the past did not allow it.  If you want to
>>> modify parameters, you can cancel the old request and submit a new
>>> one.  That is essentially what would happen in the back end anyway.
>> 
>> On 2014-11-04 19:40, Patrick Dowler wrote:
>>> It would more of a pain to keep creating new async jobs rather than
>>> negotiate over one of them and IMO changing the job can/should be part
>>> of the negotiation. This all happens in PENDING phase, before any
>>> execution, so there is no cancel per se (client could delete the old
>>> job). So this is "pre-queueing".
>> 
>> I agree with Walter, once a job has been accepted by the server it
>> should no longer be modifiable.
>> 
>> Allowing the job to be modified while it is still in the PENDING phase
>> is useful, because it provides a way for the client and server to
>> negotiate the details of the job, as described in Pat's example.
> 
> Just to be clear, I am proposing getting rid of PENDING.  To handle
> the Patrick's use-case, you can ask the service for estimates, but you
> can not modify anything that is persistent.  You can only cancel them.

So a job is submitted and automatically entered into a QUEUED state which is then persistent?
The QUEUED state can be useful in third-party data transfers where you are negotiating with two VOSpaces and do not want the job running until both client and server are agreed on the transaction. This is not an estimate but negotiation. More generally, though, the problem with getting rid of PENDING is that it will not only impact UWS but also VOSpace and possibly TAP and the code bases for those already out there.

	Cheers,

	Matthew