Necessity of ActivityDescription [was: IVOA Provenance DM -RFC- answers to comments]

[Ole Streicher]

Hi Markus,

On 26.11.18 13:01, Markus Demleitner wrote:
> On Sun, Nov 04, 2018 at 08:26:09PM +0100, Mireille LOUYS wrote:
>>>> http://wiki.ivoa.net/twiki/bin/view/IVOA/ProvenanceRFC
>>> I've posted the following to the Wiki, but I thought having it on the
>>> list might be more conducive to discussions, so here's what I my
>>> thoughts were while reviewing this.
>>>
>>> TL;DR: let's only have the core model in 1.0.  We can always add
>>> extensions in 1.1.
>> we need the ActivityDescription class and Parameter class to be able to
>> search for some specific processing type on the data.
>> Activity is only the process launched for the computation.
>> It does not hold the details of the methods , because those details are
>> factorised in the ActivityDescription class.
> 
> You mean "Find me all source extractions being done on the images of
> this data collection"?  That *does* sound like a fairly basic thing to
> want to do, yes, and from what I see in the current Activity model, it
> would, indeed, seem to be impossible just with what's there.

I do not see the point here. We do not have a common vocabulary on
activities (or activity descriptions) (yet), so to find out all source
extractions, you need some domain knowledge about the activity -- like
its name, input and output roles.

But if you have the name an, you may just query "give me all activities
which have [an activity description with] this name and where my images
were used as 'input'".

These vocabularies are not planned for (the first version of)
VO-Provenance, and I guess they would take quite some time to develop,
given that there are so many possible special activities out there. Just
have a look to the ESO pipelines; it seems difficult to impossible to
classify them in a manner that your query could be done without domain
knowledge.

> I'm sure the W3C has a plan for this -- do you know what it is?  Can't
> we just follow them or is there a use case we have they don't?

W3C does not deal with queries. They try to describe what is there, and
they assume a domain specific model on top.

Cheers

Ole