[Heig] [EXTERNAL] [BULK] Re: vocabulary update: proposal for dataproduct_type update for high energy data : event-list definition and event-bundle

BONNAREL FRANCOIS gmail francois.bonnarel at gmail.com
Wed May 7 00:20:34 CEST 2025


Dear all,
    I think I agree with Markus that we should avoid multiple #this in 
general.
    But with one single exception : different formats for the same product
    Exemples : DataLink allows to have one single line in ObsCore for an 
image which we can deliver in FITS, JPEG, PNG etc...
                       DataLink allows to one single line for a spectrum 
in ObscOre which we can deliver in VOtable, FITS, CSV, etc...
     In those cases we will have in DataLInk table record 1 : ID = 
ivo://aaa/bbb
semantics : #this
content-type : application/fits
content-qualifier : image
description " XXX survey image Target so and so in FITS format"
record 2 : ID = ivo://aaa/bbb (same as above)
                                     semantics : #this
content-type : image/jpeg
content-qualifier : image
description " XXX survey image Target so and so in Jpeg format"
    ....
     The examples given by Laurent show that a data producer can choose 
different strategies according to the mode of usage it expects from users.
           strategy 1 : the bundle is exposed in ObsCOre an then in 
DataLink #this in semantics row can only be the whole bundle
           strategy 2 : the spectrum (or event-list, or whatever science 
data) is exposed in ObsCore and then #this is this very spectrum, or 
event-list, etc... other material you want to link  to the spectrum must 
have different semantics (#calibration, #auxiliary ...)

      Answer to your last question below


Le 05/05/2025 à 22:45, Jaffe, Tess (GSFC-6601) via heig a écrit :
>
> I can add what our use case was.
>
> There was a local team building a web tool for x-ray spectra viewing 
> and quick line identification, so I asked them to use our SSA for 
> it. We then added a datalink service descriptor to our SSA results and 
> served the response matrices in the datalink table result.  (The SSA 
> result at the time had the link to the FITS file.)  It worked 
> internally with their tool for a while but the tool didn't make it to 
> production. So that was our use case.
>
> Now we are working more on our ObsTAP and its datalinks.  But 
> precisely the question of which products get their own row in our 
> ObsCore table is what we're working on now.  Presumably, whatever we 
> decide, this hypothetical tool could work with as long as the service 
> is performant. But from the client point of view, being given a 
> tarball is more annoying to code for.  I would prefer listing the 
> spectrum product alone in ObsCore and give each ancillary file its own 
> row in the DataLink result table.  I.e., list a spectrum in ObsCore 
> and return additional rows in the DataLink result for each of the 
> files that would constitute the bundle.  What would the bundle as a 
> tarball facilitate?

We discussed examples in the context of CTA and XMM. I think 
"event-bundle" records in ObsCore may be completed by DataLink records 
#this with content-type=application/OGIP or 
content-type=application/GADF (or later VODF)

In that case a dedicated software can directly process these "standard" 
formats of "bundles".


Of course another valid strategy is the one you suggest : product type 
in ObsCore : event-list , spectrum and then several records with 
#calibration for the different IRF or ARF

An extended vocabulary for IRF/ARF types (TBD) may be used in the 
content-qualifier FIELD in each of those rows for better identification.

Probably more adapted for ad hoc processing.

Cheers

François


>
>
>
> ------------------------------------------------------------------------
> *From:* heig <heig-bounces at ivoa.net> on behalf of Mireille Louys via 
> heig <heig at ivoa.net>
> *Sent:* Monday, May 5, 2025 1:50 PM
> *To:* heig at ivoa.net <heig at ivoa.net>
> *Subject:* Re: [Heig] [EXTERNAL] [BULK] Re: vocabulary update: 
> proposal for dataproduct_type update for high energy data : event-list 
> definition and event-bundle
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>
>
>
> Hello,
>
> Thanks Tess and Laurent for these examples .
>
> This was a proposal during the HE workshop last week to bring some 
> examples
>
> showing an Obscore data discovery ( obscore entry here ) and exploring
> various settings of data link scenarios .
>
> Any volunteer for  examples from other archives ?
>
> Best , Mireille
>
>
> Le 05/05/2025 à 18:14, Laurent Michel via heig a écrit :
> > Hello,
> >
> >
> >
> > Le 05/05/2025 à 08:56, Markus Demleitner via semantics a écrit :
> >> Hi Tess,
> >>
> >> On Wed, Apr 30, 2025 at 01:48:29PM +0000, Jaffe, Tess (GSFC-6601) via
> >> semantics wrote:
> >>> Possibly dumb question:
> >>
> >> Not at all; you're touching a topic that has been discussed quite a
> >> few times now without a satisfying result yet: What does it mean if
> >> there are multiple items with the same semantics in Datalink? Is it
> >> "all of them together give the thing" or is it "they are
> >> alternatives"?  Or yet something else?
> >>
> >> Previous rounds suggested that the interpretation will probably
> >> depend on the concept, but the details turned out to be fairly messy.
> >>
> >>
> >>> If an ObsCore table lists an event-bundle as a separate row with
> >>> its own product_type, and the access_url follows best practice
> >>> specifying a datalink that will return the bundle, what should the
> >>> DataLink result include as #this?  We are actively putting this
> >>> together now at HEASARC.  If the product type is simply a spectrum,
> >>
> >> That's excellent news!
> >>
> >>> our datalink result has the spectrum file as #this and the response
> >>> matrices, background, etc. as related products in the same result
> >>> table.  If the product itself is a bundle, what is the #this? Do
> >>> we have to provide a tarball or something?  Or are there multiple
> >>> #this with different dataproduct_subtypes?  The latter doesn't
> >>> sound right to me.
> >>
> >> Given my preamble, I'd avoid multi-#this.  The ideal solution would
> >> IMHO be a standard archive if the HEIG can commit to such a thing.
> >> Failing that, I think a tar archive of the individual components
> >> would be the second best thing.  CADC does something like this,
> >> although the other way round: They're handing out everything tarred
> >> together as a #package.  Offering the components individually,
> >> possibly as #progenitor-s, would help cases when people really only
> >> want to fetch a single part.
> >
> > I agree that having multiple #this is confusing (which one is the good
> > one.??).
> > In my understanding #this must match the product_type as in the
> > Obscore record.
> >
> > If a spectrum bundle is exposed in a separate row, we should have
> > something like this:
> >
> > Obscore row:
> > -----------
> > - product_type=spectrum-bundle (tbd)
> > - access_format=application/x-votable+xml;content=datalink
> >
> > Datalink response:
> > -----------------
> > - link #1
> >   - semantics=#this
> >   - content_qualifier=spectrum-bundle (TBD)
> >   - content_type=application/tar+gzip
> >   - description="spectrum file + preview + ARF + RMF + Background
> > spectrum"
> >
> >
> > If the spectrum is exposed in a separate row:
> >
> > Obscore row:
> > -----------
> > - product_type=spectrum
> > - access_format=application/x-votable+xml;content=datalink
> >
> > Datalink response:
> > -----------------
> > - link #1
> >   - semantics=#this
> >   - content_qualifier=spectrum
> >   - content_type=application/fits
> >   - description="spectrum file"
> > - link #2
> >   - semantics=#package
> >   - content_qualifier=spectrum-bundle (TBD)
> >   - content_type=application/tar+gzip
> >   - description="spectrum file + preview + ARF + RMF + Background
> > spectrum"
> >
> > I do not believe we are able to design a standard HEIG archive because
> > this too much mission/tool specific.
> > Do we really needs the archive content to be machine readable?
> > Anyway, individual files can be exposed with an adapted semantics.
> >
> > Laurent
> >
> >
> >>
> >> But at least for a prototype (and, if that works fine, perhaps also
> >> as a long-term practice), I think nobody would be terribly confused
> >> if #this were just the time series or spectrum, in particular if a
> >> content-qualifier would let machines figure out what it is they'll
> >> get.
> >>
> >> I'm not too happy with #progenitor for the individual components,
> >> though.  Perhaps datalink/core should have a concept #component with
> >> the definition "for datasets where #this is composed of multiple
> >> individual artefacts, #component rows offer access to individual
> >> artefacts.  Use local-semantics to consistently mark up the roles of
> >> the components." or so.
> >>
> >> In the end, I think we need to see what will help clients consuming
> >> this.  Do we have software that we could use to try that out? What
> >> do people use to work this #event-bundle-s?
> >>
> >>           -- Markus
> >>
> >
> > --
> > English version: https: 
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> --
> --
> Mireille Louys, MCF (Assistant Professor)
> Centre de données Astronomiques (CDS)       Equipe Images, ICube
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