(r8) SIAP-2_0-Next < IVOA

IVOA Web>IvoaDAL>SIAP-2_0-Next (revision 8) (raw view)~~EditAttach~~
---++ Common SIAP-2.0-Next and DAP1.0 page.

   * Previous material before May 2020 (most of it common with [[https://wiki.ivoa.net/twiki/bin/view/IVOA/SODA-1_0-Next][SODA-Next]])
Old "DAL future" page : https://wiki.ivoa.net/twiki/bin/view/IVOA/DALFuture

IVOA note : http://www.ivoa.net/documents/Notes/RecentDALProtocolsFeedback/index.html

IVOA interop meetings presentation :

Paris : https://wiki.ivoa.net/internal/IVOA/InterOpMay2019DAL/SIA2-SODA-next.pdf

College Park : https://wiki.ivoa.net/internal/IVOA/InterOpNov2018DAL/HiPStoFits_Prototype_IVOA.pdf

Victoria : https://wiki.ivoa.net/internal/IVOA/InterOpMayy2018DAL/DAL-Feedback.pdf

   * Additional material since May 2020 (IVOA interop meetings and Running meetings - most of it common with [[https://wiki.ivoa.net/twiki/bin/view/IVOA/SODA-1_0-Next][SODA-Next]])
    
We list presentations also look at Notes and discussions.

May 2020 virtual interop : https://wiki.ivoa.net/internal/IVOA/InterOpMay2020DAL/SIA2-SODA-nextPyVO-support.pdf

November 2020 virtual interop : https://wiki.ivoa.net/internal/IVOA/InterOpNov2020DAL/SIA2-SODA-next-status.pdf

January 2021 running meeting #7: https://wiki.ivoa.net/internal/IVOA/IvoaDAL_RunningMeetings/IVOA_DAL_RM7_etherpad.txt

February 2021  running meeting #8 : https://wiki.ivoa.net/internal/IVOA/IvoaDAL_RunningMeetings/IVOA_DAL_RM8_etherpad.txt

March 2021 running meeting #9 :  https://wiki.ivoa.net/internal/IVOA/IvoaDAL_RunningMeetings/IVOA_DAL_RM9_etherpad.txt

May 2021 virtual interop : https://wiki.ivoa.net/internal/IVOA/InterOpMay2021DAL/SIA2-nextDataSetDiscov.pdf

November 2021 virtual interop : https://wiki.ivoa.net/internal/IVOA/InterOpNov2021DAL/minoc-soda-objectstore.pdf

April 2022 virtual interop :  https://wiki.ivoa.net/internal/IVOA/InterOpApr2022DAL/SIA2SODAUpgradesExtendingSIA2toDataSetSAP.pdf

September 2022 running meeting #14 : https://wiki.ivoa.net/internal/IVOA/IvoaDAL_RunningMeetings/DAP-SODA-DALRunningmeeting.pdf

October 2022 virtual interop : https://wiki.ivoa.net/internal/IVOA/InterOpApr2022DAL/SIA2SODAUpgradesExtendingSIA2toDataSetSAP.pdf

March 2022 running meeting #15 : https://wiki.ivoa.net/internal/IVOA/IvoaDAL_RunningMeetings/DalRunning10-DL-DAP-SODA.pdf

May 2023 Bologna interop : https://wiki.ivoa.net/internal/IVOA/InterOpMay2023DAL/SIA-DAPSODA.pdf

---+++ SIAP-2.0 feedback, issues and proposals (status in May 2020)

On GitHub: https://github.com/ivoa-std/SIA

   * input PARAMETERS with limited list of values : better description ([[https://github.com/ivoa-std/SIA/issues/1][github SIA issue #1]] )
Several SIAP2.0 parameters have a limited list of possible values &ndash; Some have lists limited by protocol (and obscore)

POL (Stokes, LINEAR, etc..) DPTYPE (image, cube, visibility, timeseries ;..) CALIB : levels FORMAT : fts, jpeg , png, etc..

&ndash; Some have free string values

COLLECTION (HST, WISE, etc...), FACILITY (VLT, Keck, Chandra), INSTRUMENT (ACS, MEGACAM, etc.)

&ndash; PARAMETERs less useful if we have no prior idea of their possible values. It often happens that services do not provide these lists of parameters although section 2.1.1 However Section 2.1.20 of SIAP2.0 states : Service PARAMETER self description Any service may include a DataLink service descriptor in the vOTable output to describe itself. this descriptor would describe the supported query parameters (standard and custom) including list of values for those with a fixed list (eg. COLLECTION INSTRUMENT FACILITY DPTYPE CALIB and FORMAT) *

This will allow to discover "possibilities" of the service prior to usage and optimize the queries

The "MAY" is obviously too weak. Version 2.1 could state SHOULD or MUST

_Text change proposed in  [[https://github.com/ivoa-std/SIA/pull/23][SIA Pull request #23]] . Result can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. (FrancoisBonnarel - 2023-05-31)_

   * No input PARAMETER exists to select the RELEASE DATE ([[https://github.com/ivoa-std/SIA/issues/2][github SIA issue #2]])
ObsCore has an optional parameter "obs_release_date", but some projects complain no SIA PARAMETER allows to select on this.

Solution : create an OPTIONAL parameter to select on that ? What is the policy for OPTIONAL parameters ?

_Done with [[https://github.com/ivoa-std/SIA/pull/16][SIA Pull request #16]] . Merged in may 2022. (FrancoisBonnarel - 2023-05-31)_

   * No Wild-carding of the input PARAMETERS values exists ([[https://github.com/ivoa-std/SIA/issues/3][github SIA issue #3]])
SIAP2 PyVO interface developers and CADC complain that no wild-carding or incomplete strong value can be admitted in string parameter. Only exact matching.

What is the price to pay to add this functionality and how do we allow it ?

_Basically not admitted to avoid encoding issues. Ad hoc solution proposed for ivo identifiers. Text change proposed in  [[https://github.com/ivoa-std/SIA/pull/23][SIA Pull request #23]] . Result can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. (FrancoisBonnarel - 2023-05-31)_

   * input PARAMETERS values are case sensitive ([[https://github.com/ivoa-std/SIA/issues/4][github SIA issue #4]])
What is the price to pay to allow case-insensitive and how do we do that ?

_Several string values PARAMETERS may be case insensitive, except where the "data model" forbids it (COLLECTION, FACILITY, INSTRUMENT). Text change proposed in  [[https://github.com/ivoa-std/SIA/pull/23][SIA Pull request #23]] . Result can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. (FrancoisBonnarel - 2023-05-31)_

   * POS=RANGE examples inconsistent with spec ([[https://github.com/ivoa-std/SIA/issues/5][github SIA issue #5]]) (From Pat Dowler)
The spec clearly states that RA is in [0,360] and DEC is in [-90,90] but some POS=RANGE ... examples use -Inf and +Inf (probably copied the idea from use of open ended intervals in other params).

I consider this a bug in the example that should result in a fix and erratum because I recall we explicitly decided to not have services doing range reduction.

_Done with [[https://wiki.ivoa.net/twiki/bin/view/IVOA/SIA20Err1][SIA2.0 erratum 1]] . Accepted 2023-04-05. (FrancoisBonnarel - 2023-05-31)_ 

   * 1 shot discovery (and then access) to cutouts was possible in SIA1 but no more in SIA2 ([[https://github.com/ivoa-std/SIA/issues/6][github SIA issue #6]])
SIAP1 had « cut out » and « mosaic » modes besides « archive » mode &rarr; 1 shot before access but only spatial We now have : SIAP2.0 or ObsTAP which deal with all axes

SODA : for cutouts only (all axes) +DataLink (Service descriptor and/or {links} table) &rarr; 2 shots before access (instead of 1)

Although it is pretty useful to have the 2 shots sometimes (allow the user to choose the actual limits according to ObsCore content and general context) there have been some complains (SkyView people for example also others) that the one-shot functionality disappeared. It would be perfectly possible to provide it by replacing the full retrieval or datalink url in access_url by a SODA url. SODA URL parameters are common with SIA. Where SIA Parameters values constrain the discovery, SODA parameters force the cutout dimensions.

A capability "virtual data generation" would have to be added to the service. If it exists how do we choose to provide these cutouts by a new "VIRTUAL" boolean parameter? Or by providing two lines in the response with the same obs_id ? The obscore values will be different, encluding publisher_did, but the observation will be the same

_Two different ways of implementing RETRIEVEMODE PARAMETER (=VIRTUAL) can be considered. Using full SODA Queriy URL in access_url or using service descriptor with ref for all input parameters. Text change with two alternative solutions proposed in  [[https://github.com/ivoa-std/SIA/pull/23][SIA Pull request #23]] . Result can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. Still to be discussed. (FrancoisBonnarel - 2023-05-31)_

   * Possible confusion between FORMAT and RESPONSEFORMAT parameter ([[https://github.com/ivoa-std/SIA/issues/7][github SIA issue #7]])
Alberto Micol 2019/03/&4 :

SIA specifies:

"The FORMAT parameter specifies response format(s) (the access_format column from the ObsCore [7] data model). This column describes the format of the response from the access_url (see 3.1.3) so the values could be data file types (e.g. application/fits) or they could be the DataLink [8] MIME type."

The initial part of the sentence mentions "response format(s)", which that greatly overlaps,

and generates confusion (at least in my mind), with the following DALI specification:

"The RESPONSEFORMAT parameter is used so the client can specify the format of the response (e.g. the output of the job)."

The SIA FORMAT and the DALI RESPONSEFORMAT are two different things, and I think that should be better clarified

in the text of the next SIA version. Could that be done?

_Done with [[https://wiki.ivoa.net/twiki/bin/view/IVOA/SIA20Err2][SIA2.0 erratum 2]] . Accepted 2023-04-05. (FrancoisBonnarel - 2023-05-31)_ 

   * SIA2 cannot discover rebinned data like SIA1 was able to do ([[https://github.com/ivoa-std/SIA/issues/8][github SIA issue #8]])
Extending VIrtual SIAP2 as described in issue re-gridding/rebinning along a specific WCS can be done by adding this functionality to the virtual data discovery functionality described in issue #6. The access URL would be a SODA URL with the additional parameters proposed in SODA issue #4

An alternative is allowing SIA1 parameters of the MOSAIC mode to SIA2 interface


_This is related to a change in SODA. Text change proposed in  [[https://github.com/ivoa-std/SIA/pull/23][SIA Pull request #23]] . Result can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. (FrancoisBonnarel - 2023-05-31)_

   * It is not possible to query SIA services by MOC ([[https://github.com/ivoa-std/SIA/issues/9][github SIA issue #9]])

MOC (as well as STMOC, and maybe STEMOC) has proven to be a very efficient way to describe coverage of data and is used for discovery of data. It has been often discussed and also during last interop that it should be useful to query SIA services by MOC ? It should probably be with a new parameter and not via POS considering that it is probably more useful to have STMOC or STEMOC, than spatial MOC alone. This is also valid for SODA of course (SODA Issue #5). I wonder if this new parameter should not be standardized by DALI

_Text change proposed in  [[https://github.com/ivoa-std/SIA/pull/23][SIA Pull request #23]] . Result can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. (FrancoisBonnarel - 2023-05-31)_

   * extension of SIA-style protocol usage outside the image/cube "camp" ([[https://github.com/ivoa-std/SIA/issues/10][github SIA issue #10]])

There was a demand to be able to use a parameter based interface "à la" SIAP2 for other dataproduct_types than cube and image
DPTYPE constraint should be relaxed
eg: measurements
time-series
etc....
CADC actually created a service like this.
What could be the name? SIA is no more appropriate
For time-series this has been discussed in the following ivoa note: http://www.ivoa.net/documents/Notes/TimeSeriesDiscoveryAndAccess/index.html
For some dataproduct_types a specific ObsCOre extension may be needed; For TimeSeries this was discussed in recent past. see for example:

https://wiki.ivoa.net/internal/IVOA/InterOpOct2017TDIG/IVOA2017Santiago-DiscussionTDIG-DM-DAL-Session1.pdf

or

http://volute.g-vo.org/svn/trunk/projects/time-domain/time-series/note/TSSerializationNote.pdf

_Long discussion on this led to a new specification  called DAP (see below) and  result can be seen in  [[%ATTACHURL%/DAP.pdf][internal draft below]]. (FrancoisBonnarel - 2023-05-31)_

---+++ DAP 1.0 proposal _(starting from may 2022 - FrancoisBonnarel - 2023-05-31)_

  Basically it was decided at the May 2022 interop to move to a new specification of a parameter based interface called 'Dataset Access Protocol" or 3DAP".

   The new github project strating from SIA2.9 is there : https://github.com/ivoa-std/DAP

   All the changes in text from SIA2.0 to extend the scope of such a specification can be found in [[https://github.com/ivoa-std/DAP/pull/3][DAP PR #3]]. This PR also contains also all the changes for SIA2.0 described above. The   https://github.com/ivoa-std/SIA project is now idel and is there for legacy if issues and discussions.
Result of all the changes can be seen in [[%ATTACHURL%/DAP.pdf][internal draft below]]. 

FrancoisBonnarel - 2023-05-31



---+++ SODA-1.0 feedback, issues and proposals

Now available here : https://wiki.ivoa.net/twiki/bin/view/IVOA/SODA-1_0-Next

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Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
pdf	DAP.pdf	r2 r1	manage	630.9 K	2023-05-17 - 22:19	FrancoisBonnarel	first attempt transition SIA -- DAP
Topic revision: r8 - 2023-05-31 - FrancoisBonnarel
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