(r5) DALFuture < IVOA

IVOA Web>WebPreferences>DALFuture (revision 5) (raw view)~~EditAttach~~
<br /> <!--
      * Set ALLOWTOPICRENAME = IVOA.TWikiAdminGroup
-->

---+ DAL Future - discussion page

This page is meant to gather opinions, feedback and proposals for DAL future (see [[http://wiki.ivoa.net/internal/IVOA/InteropOct2016DAL/DAL_Future.pdf][Trieste 2016 Fall Interop presentation]]).

The underlying question is what will be the main evolution of the DAL protocols in a near future (SIA, !SODA, TAP, !ADQL, !DataLink, etc.).

The main drivers are:

   1 CSP priorities : what is achieved and what is not achieved.
   1 Feedback from implementation of recently recommended protocols (SIA, !DataLink, !SODA, TAP new version)
   1 Multidimensional data access roadmap as established in october 2013 in Hawaï (Fall Interop + ADASS).
Properties to consider:
   * Data Type
   * Functionalities
   * Software Design
   * Position in IVOA landscape
(see [[http://www.adass2016.inaf.it/index.php/participants-all/4-poster/163-molinaro-marco][ADASS XXVI DAL poster]] for reference)

Contribution can take the usual forms: linked pages to topics listed below (or added ones), mailing list follow up from the topics.

(please, when creating a page to link from a topic here, use a DALFutureTopic TWiki name for the new page)

---+++ Data Type

Add Time Domain ( *HIGHEST Scientific priority: see [[http://wiki.ivoa.net/twiki/bin/view/IVOA/CSPTimeSeries][CSP Time Series use cases]]*)

   * use cases
   * ideas for solutions
   * attempts and prototypes reports

---+++ Functionalities

   * Feedback : what is missing/inadequate in current protocols
   * Extended metadata (for Cubes and Time Domain)
   * Extended server side data services (regridding, deconvolution, etc.)

---+++ Software Design

---+++++ Interface design

   * Feedback on current interfaces

_Recently I discovered that  calls to datalink+SODA, outside ObsCore and SIAv2 context are available in VizieR, but also in GAVO. Markus is now using in SIA 1.0 responses (see  http://dc.zah.uni-heidelberg.de/lswscans/res/positions/siap/siap.xml?POS=311.41098458333335,30.723715361111108&SIZE=2.64&FORMAT=image/fits) It sounds reasonable and  I can imagine we wil find more of that in the future. But here there are already fields with  utypes Access.Reference in le SIA mai n part, it is now  difficult/impossible to recognize that a given link will return Datalink or something else._

_On the other side, the  Datalink VOTable response doesn't  contain any signature allowing to  recognize a posteriori that it has a  datalink content. That's a pity. This would have been harmless and could simplify everything._ 

_This has direct consequence on  Aladin v10 (or any other client), which has the code necessary to perform specific actions for DataLink., cannot benefit from all these standardisation efforts and is limited to display the DataLink result as a simple,VOTable without coordinates , or still worse  in a Web navigator._ 

_The good point is that we are now close to a real usage and no more in prototyping. THis kind of  usage is probably  wider than what  was imagined initially for datalink  Aladin is close to make something of it there is now a couple of servers which deliver these things. JUST sad that everybody is using it his own way  with the consequency that it remains unusable, while nearly nothing is missing to fix that._

_So, I would recommend two changes:_

   _-A simple method to identify the  links and to discover what they are supposed to return_

        _solution 1: a specific utype for datalink URL (ex: utype=Access.Reference.Datalink.1.xxx")_

        _solution 2: an appropriate LINK in the  FIELD definition (ex: LINK content-type="application-stream/votable;datalink" ...)_

    _-A signature in the VOTable, for example using an INFO tag  or as an attribute of RESOURCE ,  RESOURCE type="result;datalink"..._

_These "solutions" are just examples to illustrate the idea. WE have to check their validity with regard with the standard evolution. -- IVOA.PierreFernique - 2017-03-07_

   * Driving extended functionalities
   * Standard definition of custom services

---+++++ Pushing code to the data

   * Science cases
   * Attempts and prototypes

---+++++ Formats and Languages

   * Json, !PQL, PDL, etc.
   * What to use next ?

---+++ TAP evolution

   * From relational databases to...
   * Relaxing !ADQL ?

---+++ Position in IVOA landscape

---+++++ Merging DAL protocols, !HiPS and MOC

   * !HiPS is also a discovery and access mode: How to marry service approach and !HiPS Approach in both ways ?
   * Querying services by MOC : is that necessary ?

---+++++ Data Models

   * !ObsCore
   * !DataSet Metadata
   * ND-Cube
   * !SparseCube
   * !STC
   * other...

---+++++ Updating SCS

SCS still requires VOTable 1.1 and has some other quirks that makes it needlessly incompatible with the rest of the DAL landscape (in particular, it's totally DALI-incompatible). We should figure out how we can evolve it to be less odd with minimal disruption to existing services and clients (e.g., relaxing VOTable requirements, support for DALI MAXREC, RESPONSEFORMAT, metadata discovery).  -- IVOA.MarkusDemleitner - 2017-03-01
Topic revision: r5 - 2017-03-07 - FrancoisBonnarel
IVOA
Log in or Register
IVOA.net
Wiki Home
WebChanges
WebTopicList
WebStatistics
Twiki Meta & Help
IVOA
Know
Main
Sandbox
TWiki
TWiki intro
TWiki tutorial
User registration
Notify me
Working Groups
Interest Groups
Committees
Stds&Procs
www.ivoa.net
Documents
Events
Members
XML Schema