[jsdl-wg] Question on file stage-in (fwd)

[Steve McGough]

JSDL 1.0 does not support conditionals. These were removed (in their 
last form - profiles) from the JSDL spec at GGF 13.

It is a subject we wish to re-visit this post JSDL 1.0 release.

steve..

Andrew Grimshaw wrote:

>All,
>Is there a way to do condition statements in JSDL, in other words the
>implementation that is "executing" the JSDL can choose which of several
>options?
>
>Andrew
>
>-----Original Message-----
>From: owner-jsdl-wg at ggf.org [mailto:owner-jsdl-wg at ggf.org] On Behalf Of
>Steve McGough
>Sent: Thursday, June 09, 2005 7:07 AM
>Cc: JSDL WG
>Subject: Re: [jsdl-wg] Question on file stage-in (fwd)
>
>I think at this point we should remember that JSDL 1.0 is a minimum 
>specification. All consumers need to be able to deal with the elements 
>we define.
>
>I do agree with Andrew that optimised transfers are very useful and it's 
>a prime example of an extension to JSDL that should be done. Then at 
>some point in the future you'll have services which handle the useful 
>extensions and some which don't. People will submit jobs to services 
>which have the extensions they desire - though could use the others if 
>they have to. This will hopefully cause services which don't have the 
>extensions to upgrade or "mimic" the features so they do get jobs. This 
>is something I've already seen signs of.
>
>steve..
>
>Donal K. Fellows wrote:
>
>  
>
>>Andrew Grimshaw wrote:
>>
>>    
>>
>>>In the data staging elements there is a creation flag that indicates 
>>>whether
>>>to over-write or append.
>>>
>>>Often, one only wants to overwrite if the target and the source are
>>>different, for example if I am using a large data set that changes
>>>infrequently or several jobs on the same resource will use the "same" 
>>>input
>>>file.
>>>Is there a way to do conditional stage in?
>>>      
>>>
>>My understanding is that the implementation is free to use some
>>mechanism outside the JSDL scope to optimize downloads. From the JSDL
>>perspective (not that this is the only valid perspective, of course) it
>>doesn't matter all that much. Looking at the latest version of the spec
>>though, I see that the value "jsdl:dontOverwrite" could be interpreted
>>to mean "transfer only if not pre-existing". Of course, at that point
>>you then have to worry about whether the two ends refer to the same
>>data, but if you're piling the data into some job-specific dir that's
>>IMO not a huge issue.
>>
>>    
>>
>>>I know the document says
>>>
>>>"More complex file transfers, for example, conditional transfers 
>>>based on
>>>job termination status are out of scope. "
>>>
>>>But we're talking about a major performance optimization.
>>>      
>>>
>>Well, perhaps. But if we add it, we have to worry about systems that
>>don't have a mechanism for doing this sort of thing in the first place.
>>Indeed, the JSDL 1.0[*] spec leaves out many things that could be major
>>performance wins (e.g. compressed data transfers) either because they're
>>complicated in their own right, or because we decided to get a spec
>>going *this* decade as opposed to the next one. :^) None of which means
>>that we will not go back and revisit these issues once there is some
>>more data and experience reports available on actual deployed
>>implementations. In particular, as it is a spec put together by mainly
>>compute guys, we know that the data-related part is in need of fleshing
>>out in the future.
>>
>>We've not reached the end of the story. Maybe just the end of the
>>chapter instead. ;^)
>>
>>Donal.
>>[*] As a side note, it should be done just about now as I write this. :)
>>
>>
>>    
>>
>
>  
>

-- 
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Dr A. Stephen McGough
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