WG: OGF PGI Session 3, 14:00-15:30 Draft Minutes

22 Sep 2011


      Was blocked...
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-- -----Ursprüngliche Nachricht-----
-- Von: Daniel S. Katz [mailto:dsk@ci.uchicago.edu]
-- Gesendet: Donnerstag, 22. September 2011 09:39
-- An: Steve Crouch
-- Cc: pgi-wg@ogf.org
-- Betreff: Re: [Pgi-wg] OGF PGI Session 3, 14:00-15:30 Draft Minutes
-- 
-- I wasn't at this session, unfortunately.  The name shortcuts under attendance makes it look like I was...
-- 
-- Dan
-- 
-- 
-- On Sep 21, 2011, at 3:28 PM, Steve Crouch wrote:
-- 
-- > 14:00-13:30 PGI Session 3
-- > -------------------------
-- >
-- > Chair: Andrew Grimshaw
-- > Minutes: Steve Crouch
-- >
-- > Attendance:
-- >
-- > Name shortcuts:
-- >  AG - Andrew Grimshaw
-- >  EU - Etiennce Urbah
-- >  DK - Daniel Katz
-- >  OS - Oxana Smirnov
-- >  JPN - JP Navarro
-- >  KS - Katsushige Saga
-- >  SC - Steve Crouch
-- >  DM - David Meredith
-- >
-- > New actions:
-- >
-- > Minutes
-- >
-- > Discussion of state model - how can we accommodate additional states?
-- >
-- > EU: doc number is 16306 under OGSA-BES WG on GridForge.
-- >
-- > [Page 31, fig 6]
-- >
-- > EU: take same states as original BES, add in transitions. Add purge
-- > finished -> [end], add failure transition pending -> failed. If
-- > cancelled -> [end], it's purged.
-- >
-- > AG: this is change in underlying state model.
-- >
-- > EU: could drop it, it exists on one system. If it doesn't fit, we drop it.
-- >
-- > EU: next diagram for held states [fig 7, pg 34]. Based on original BES,
-- > only added some transitions.
-- >
-- > AG: if specified to go into suspended state initially in JSDL, it starts
-- > in suspend until told to resume ('proceeding'). Transitions from
-- > suspended/proceeding to both cancelled and failed. Still need to add a
-- > transition. Automatic resubmission perhaps not put in.
-- >
-- > AG: other one is extended job state [referring to session slide 3] from
-- > RENKEI.
-- >
-- > KS: EU covered this in more detail yesterday. (Discussion of incoming
-- > queues for pre-processing).
-- >
-- > JPN: other terms meaning same thing: pre-processing:pending,
-- > pre-processing:complete.
-- >
-- > AG: are we trying to go to a different state model? We'e handled this as
-- > specified in the spec, which has substates dealing with staging in and
-- > out. e.g. staging-in is pre-processing state. Also running:executing is
-- > a substate. Didn't we want to stay with the basic state model and extend
-- > via substates? This state model is extended.
-- >
-- > EU: not compatible with basic state model?
-- >
-- > KS: mapping exists from this to basic state model substates [next slide].
-- >
-- > AG: good profile some of these substates - we need to know what these
-- > substates actually mean. Are these proposed JSDL extensions?
-- >
-- > KS: this implementation is just for testing. We don't care deeply about
-- > extensions.
-- >
-- > AG: you name a substate where you want it to stop?
-- >
-- > KS: yes.
-- >
-- > AG: thought something similar to EU's idea. In original state model, two
-- > place for helds (need pre and post): in running (as EU did), in pending,
-- > and terminated held/finished held failed/held. But this is subsumed into
-- > EU's.
-- >   Do we want to give advice for how to order additional substates? Do
-- > we recommend these in proceeding or suspended? If we use substates as in
-- > data staging, execution in running where to put the helds?
-- >
-- > SM: better to have a named state for data staging pre/post. Confusing
-- > for client otherwise.
-- >
-- > AG: optional client initiated staging hold. Letting client do whatever
-- > they want to do. Dont want to hold for all purposes.
-- >
-- > Mike: you know it's held for pre-processing.
-- >
-- > AG: what does delegated refer to? Delegated queue for queued, delegated
-- > running for running.
-- >
-- > SM: want to have pre and post for delegated.
-- >
-- > EU: names not well chosen.
-- >
-- > AG: suggest change names for some of these states.
-- >
-- > SM: delgated - incoming is queued.
-- >
-- > AG: delegated should be processing. Delegated:incoming should be
-- > delegated:queued-in. Processing:outgoing (renamed) not visible to
-- > outside, used as transitory state.
-- >
-- > Mike: no error around it, it's mandatory right?
-- >
-- > AG: if somebody were to subscribe to notification about this, ...
-- >
-- > AG: processing:running, processing:hold.
-- >   If no queueing system, just executes - can it go directly to running.
-- >
-- > SM: debugging problematic. Held not implemented for all middlewares.
-- >
-- > AG: not sure I like this (confusion with states of running jobs for
-- > held/running for executing jobs).
-- >
-- > SM: have u seen EMI execution service? Can take some of these from there.
-- >
-- > AG: keep same 5 states.
-- >
-- > SM: have attributes for substates.
-- >
-- > AG: need to agree on these attributes. To avoid having to guess on
-- > substate meanings.
-- >
-- > SM: many reasons for including more info in substates e.g. errors -
-- > storage is down, etc.
-- >
-- > EU: doc - 10th March on pgi list. PGI execution specification.
-- >
-- > [Discussion about pg 20 and state definitions - pre-processing and
-- > processing]
-- >
-- > AG: mapping of these states to our discussed states.
-- >
-- > SM discusses how this mapping works.
-- >
-- > AG: referring to current state model...
-- >   Agreed yesterday not to change state model otherwise, have to change
-- > spec. Profile substates, don't have to.
-- >
-- > SM: too simple to represent all things. Problems with users to
-- > distinguish clearly with states.
-- >
-- > AG: use [substates] and no pushback from users.
-- >
-- > Mike: but we'd have to change the spec.
-- >
-- > AG: want to expedite the process. If it can be done in context of the
-- > existing state model, it vastly simplifies things unless it's too ugly.
-- >
-- > SM having multiple states.
-- >
-- > AG: how do we feel about this.
-- >
-- > SM: many substates of failed - how do we identify that?
-- >
-- > SC: this would break state model, new model, should use existing spec
-- > where possible.
-- >
-- > SM: make concept smoother - define running, focus on pre/main/post
-- > processing.
-- >
-- > AG: we went around the state discussions before, with substates you can
-- > model everything.
-- >   Doing a whole new spec would take longer.
-- >
-- > SM: one more possible point - model from EU/KS they have this community
-- > requirement.
-- >
-- > AG: NAREGI state model - all these collapse into running.
-- >
-- > SM: limiting, should find a better way.
-- >
-- > AG: can't go backwards and change the document.
-- >
-- > SM: staging as substate - what does this mean?
-- >
-- > Mike: it may need to change anyway. A cleaner way would be to redo this.
-- >
-- > SM: substates of failed, terminate...
-- >
-- > AG: legitimate to do this in model.
-- >
-- > MM: problem we found was no additional additional transition to failure
-- > state. It can occur at any moment. We introduced artificial transition
-- > to failure state.
-- >   Afraid about too much substating of running state - other substates
-- > have more informative meaning e.g. running: data-staging.
-- >
-- > AG: if we do a new version of the spec base it on existing spec, and
-- > just change the bits we need e.g. FactoryAttributes, vector operations,
-- > but keep it simple, otherwise it will escalate - genie out of the bottle.
-- >   SM is right - various people have substated this in very similar ways
-- > in implementations - substates in running. This is fine, can even have k
-- > layers deep of substates. What are transitions introduced? To error states?
-- >
-- > AG: too much of a decision to reach today. If we redo the spec, we
-- > timebox it. If not, we will profile. Otherwise it will get into a
-- > problem of arguing about stuff as in PGI.
-- >
-- > JPN: use cases for these requirements?
-- >
-- > AG: held states got us here. They wanted client-initiated held states
-- > for data staging, then can say 'go'. Then be able to stop it afterwards.
-- > No requirement for us, since data staging is automated, or done manually.
-- >
-- > JPN: requirement for all BES to support thee states?
-- >
-- > AG: specified in JSDL, if you don't support it, you throw a fault.
-- >
-- > EU: not in favour of manual staging in complicated state model. Have
-- > documented it in documentation so people can understand these
-- > complexities. Advocate existing BES states, just adding few transitions
-- > that are missing e.g. pending -> failed.
-- >
-- > AG: pending -> failed could be done as an addendum e.g. it was
-- > forgotten, ok. Adding new states is different.
-- >
-- > SM: have given this requirement to PGI and EMI.
-- >
-- > EU: have a requirement to users. They should think about workflow model
-- > before trying to send jobs.
-- >
-- > SM: our users are expecting this held, manual staging. We shoulnd't
-- > perhaps introduce hold mechanism, just implement simple flags. But
-- > doesn't have to be supported.
-- >
-- > EU: do we have to implement new state model.
-- >
-- > SM: no. Different issue.
-- >
-- > EU: related to post/pre processing.
-- >
-- > AG: hold and manual can be substated away. SM wants to restate
-- > misleading substates.
-- >
-- > SM: e.g. running:queued.
-- >
-- > EU: just rename.
-- >
-- > DM: haven't heard a convincing argument for these pre/post processing
-- > substates...
-- >
-- > AG: it's ugly, a bit of ugly at a time. Term for this: technical debt.
-- > The easy path, some point in future clean it up, not today - fine with
-- > me! Not me who will have to implement.
-- >   SM from UNICORE. PGI and EMI had this as their requirements. PGI/WG
-- > had this as a requirement driven from gLite and ARC. But now UNICORE?
-- >
-- > SM: yes.
-- >
-- > AG: how functionality differnet from telling them to copy data in first?
-- >
-- > SM: job starts, get EPR & storage service reference, use this to stage
-- > data into. Can upload files/directory into this, once done, start job
-- > physically.
-- >
-- > AG: 3 choices
-- >  1) We stay on profile only path, incorporate reqs fully later on
-- >  2) Bite bullet and do the spec rewrites
-- >  3) Addendum - additional profile to stick changes in only
-- >
-- > AG: addendum to add state ok, changing state space wouldn't ba an
-- > addendum as such.
-- >   Other than UNICORE, others want to profile.
-- >   UNICORE - do it properly, rewrite.
-- > Need input from others - gLite, CREAM, SAGA, NorduGrid, etc. Need to get
-- > this approach right.
-- >
-- > SM: first priority data staging profiling ok, state model - secondary.
-- > Thirdly (personal) BES - meaning of substates from user's point of view.
-- >   Rename running as processing.
-- >
-- > AG: addendum?
-- >
-- > Mike: can we do all this in profiles?
-- >
-- > AG: don't think vectors can be done this way. Is it important? Not sure
-- > - may slide on important scale. Those that wanted it have walked away
-- > from the table.
-- >
-- > EU: in EDGI, we're implementing handling of vectors. Tell users if you
-- > want vector, you explain in separate file internally and generate
-- > internally as many jobs as necessary using existing client interfaces.
-- >
-- > AG: support in our client implementation by generating multiple internal
-- > JSDLs from a single one, returning single EPR. If you send list, we'll
-- > accept and start them all.
-- >   Param sweep spec never says what to return.
-- >
-- > SM: rename states.
-- >
-- > AG: perhaps not a bad idea. Notion of addendums to specs; very easily done.
-- >   a) transition from pending to failed.
-- >   b) rename running to processing.
-- >
-- > AG: can have conditional - support both running and processing (but they
-- > mean the same thing).
-- >   On to the substate model. Assuming processing, not running. Perhaps
-- > not enough time. Back and forth transitions are problematic, not sure
-- > it's way to go. Alternative way would be to have hold states within
-- > processing; not clear how existing imps that break down running into
-- > substates would handle this. Look at RENKEI's mapping.
-- >
-- > EU: see previews drawing.
-- >
-- > KS: we implement pre-processing/post-processing only for data staging.
-- > Maybe original PGI specification state model comes from strawman. Also
-- > doc says pre-post used for data staging.
-- >
-- > AG: think they are.
-- >
-- > KS: implement this state model. In our system we have workflow system,
-- > with this system, we can transfer data directory from and to computer
-- > resources. We implemented these states.
-- >
-- > EU: pre/post processing not only for manual but automatic data staging.
-- >
-- > AG: right.
-- >   Not a strictly requirement to support suspend/resume.
-- >
-- > AG: consensus to take running renamed as processing, change from
-- > running:stage-in/running:stage-out to new processing states.
-- >
-- > SM: how to do this resume in service?
-- >
-- > AG: discussed yesterday, new port type.
-- >
-- >
-- >
-- >
-- > --
-- > Dr Stephen Crouch,
-- > Software Architect,
-- > OMII-UK,
-- > Electronics and Computer Science,
-- > Room 4067, Level 4, Building 32,
-- > University of Southampton,
-- > Highfield, Southampton SO17 1BJ
-- > Tel: +44 (0)23 8059 8787        EMail: s.crouch@software.ac.uk
-- > Fax: +44 (0)23 8059 3045        WWW: http://www.ecs.soton.ac.uk/~stc
-- > _______________________________________________
-- > Pgi-wg mailing list
-- > Pgi-wg@ogf.org
-- > http://www.ogf.org/mailman/listinfo/pgi-wg
-- 
-- --
-- Daniel S. Katz
-- University of Chicago
-- (773) 834-7186 (voice)
-- (773) 834-6818 (fax)
-- d.katz@ieee.org or dsk@ci.uchicago.edu
-- http://www.ci.uchicago.edu/~dsk/
-- 
-- 
--

Morris Riedel

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