[jsdl-wg] DataStaging concerns

[Michel Drescher]

Hi Peter,

thanks for your suggestions. Here're some answers to some of your your 
issues:

On 19 May 2005, at 21:45, Peter G.Lane wrote:

> Hi all,
>
> Forgive me if I'm reiterating on a topic.  I've only be reading up on
> JSDL since yesterday.  I have a few concerns about the DataStaging
> section.  Primarily, I'm wondering if it really makes sense to have it
> as part of the core schema.  I think it would be better to have
> extensions like POSIXApplication for more specific DRM configurations. 

I think this is one of the candidates to ignite a religious war. No pun 
intended, but if the standard JSDL DataStaging doesn't fit you needs, 
then don't use it - its optional anyway - and introduce your own 
extension for your needs, as you suggested. Besides the war of 
syntactic sugar (SCNR) DataStaging is part of JobDescription to 
emphasize two things:
a) A Job, as JSDL understands it, comprises of the phases Stage in, run 
application, and stage out.
b) More complete, again as JSDL understands it, a job submitted to a 
job execution system comprises of data to operate on (or to produce), 
an application that executes these operations, and a set of resources 
that are used by the application.

> Here are some of my thoughts:
>
> 1) There's still controversy over whether staging should or should not
> be integrated into a DRM.  As far as I can tell, for example, the BES
> doesn't have any plans to implement staging.  DRMMA makes this
> optional.  If BES ends up using JSDL, wouldn't this be a violation of
> the spec which requires each element to be supported in some way?

You got a point there, and this will be addressed in the coming days 
(having F2F meetings of OGSA-BES *and* OGSA-JSDL in London at Imperial 
College).

> 2) There's no distinction between a stage-in or stage-out flavor of the
> staging directives.  I guess it's up to the service to decipher this so
> that it can perform the staging at the appropriate point in the life
> cycle.

It is not really up to the service. A DataStaging element has either a 
Source child element, a Target child element, or both. A Source element 
being present clearly tags a DataStaging element to be processed in the 
stage in phase of a JSDL job. A Target child element, respectively, 
requires its DataStaging parent being processed in the stage out phase 
of the JADL job. Having both Source and Target elements indicates that 
the containing DataStaging element needs processing in both stage in 
and stage out phases of the job execution process.
So in the end, it's rather indirectly encoded in DataStaging itself.

Cheers,
Michel