Proposals for VOSpace (data staging property)

[Dave Morris]

Hi Sonia,

You raised several good suggestions in your email. To avoid confusion 
I'll reply to each one in a separate email thread.

On 2021-06-11 13:31, Zorba, Sonia wrote:
> 2. Add a standard property to indicate that a data node doesn't contain 
> its
> data yet (so data has to be retrieved using a pullToVoSpace operation
> before being able to download the data using a pullFromVoSpace).

At the moment, this is fairly specific to your use case. I can see how 
this might be useful in other cases, but it would need some work to make 
it generic.

As I understand it, if this property is True, then the client needs to 
initiate an internal data transfer from your tape system to your file 
transfer system, using an internal transfer protocol, before an external 
data transfer can access the data. Which works, because your client 
knows what this property means and what action it needs to take.

I'm not (yet) convinced that there is a case for making this property 
part of the IVOA standard(*). However, I think Sara and I may need to 
have something similar for the VOSpace/Rucio bridge we are working on, 
so perhaps we can work together to create a generic solution that could 
eventually become part of the IVOA standard.

Cheers,
-- Dave

(*) This is just my opinion, I don't have an official role in this. 
Brian is the editor so in the end he decides what should or should not 
be included in the standard.

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Dave Morris
Research Software Engineer
Wide Field Astronomy Unit
Institute for Astronomy
University of Edinburgh
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