Draft VOEvent 2.1

[Roy Williams]

Hi Baptiste
I appreciate that you wish to handle events that occur in more complex WhereWhen specifications, such as relative to other planets or satellites, or as a probability distribution (LIGO/Virgo).

In your document "VOEvent 2.0 Schema limitations", there are three problems stated with VOEvent 2.0, and one of those is about gravitational wave probability distributions. For this latter case, a solution already exists within the existing schema, and has been adopted. Perhaps there are similarly simple, flexible ways to handle the other two cases? If LIGO/Virgo can work with typed Groups, can't you too? Please explain why new and complex XML schema is a better solution.

The real problem though, lies with VOEvent itself being (a) tied to XML and (b) in a state of flux.

By extending the schema, you make it much more difficult to express VOEvent in other formats such as JSON or AVRO, formats more suitable for the upcoming ZTF and LSST event streams. However, if we convert the existing 2.0 schema to AVRO, we can have it all ready by the time these new event firehoses are switched on. But if you require the IVOA to approve a 2.1 schema, they will be arguing for the next two years, the standard will be seen as unfinished, and astronomers will not want to work with it. Therefore something else, something ad hoc, will be used for ZTF and LSST, and VOEvent will lose its progress.

Roy

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Royal Observatory Edinburgh
roy at roe.ac.uk
07542 869986
________________________________
From: Baptiste Cecconi [baptiste.cecconi at obspm.fr]
Sent: 02 November 2017 4:53 PM
To: Roy Williams
Cc: voevent at ivoa.net
Subject: Re: Draft VOEvent 2.1

Hi Roy,

here are a few links to the IVOA wiki where you will find material for the case we have been raising. I’ll prepare a cleaner document in the coming days.

http://wiki.ivoa.net/internal/IVOA/InterOpMay2017-TD/lesidaner_interop_voevent.pdf

http://wiki.ivoa.net/twiki/bin/view/IVOA/InterOpMay2017-TD-001

http://wiki.ivoa.net/internal/IVOA/InterOpOct2017TDIG/lesidaner_interop_voevent.pdf

Sincerely
Baptiste

Le 2 nov. 2017 à 16:59, Roy Williams <roy at roe.ac.uk<mailto:roy at roe.ac.uk>> a écrit :

Hi Baptiste
I find it difficult to understand what is being proposed from this list of changes, since I was not present at the discussions. Is there a presentation or document that explains what you are trying to achieve, and how your proposed changes achieve your goals? Have you considered using the VOEvent syntax itself without schema changes, with typed Groups? Can you provide an example event using your proposed new schema?
Thank you
Roy Williams

---
Royal Observatory Edinburgh
roy at roe.ac.uk<mailto:roy at roe.ac.uk>
07542 869986
________________________________
From: voevent-bounces at ivoa.net<mailto:voevent-bounces at ivoa.net> [voevent-bounces at ivoa.net<mailto:voevent-bounces at ivoa.net>] on behalf of Baptiste Cecconi [baptiste.cecconi at obspm.fr<mailto:baptiste.cecconi at obspm.fr>]
Sent: 02 November 2017 3:20 PM
To: voevent at ivoa.net<mailto:voevent at ivoa.net>
Subject: Draft VOEvent 2.1

Dear colleagues,

during the discussions at IVOA last week, Pierre Le Sidaner and I have mentioned our need for updates in the VOEvent 2.0 schema, in order to fit our needs in Solar and Planetary sciences. We have prepared a draft VOEvent 2.1, trying to make sure it stays fully compliant with VOEvent built with version 2.0 of the schema. We would be grateful to have your view on this proposed draft version. The main changes are recalled below (but are available as comments in the XML schema file):

Revision 2.1 2017/11/02 BaptisteCecconi
- added "AuthorURI" in "Who"
- removed restricted list of "AstroCoordSystem": previously "idValues" type, now "xs:string"
- removed "idValues" type (and references)
- added annotation in "AstroCoords/Time" (according to STC-1.30)
- added "AstroCoords/PositionName" as "xs:string"
- added annotation to "AstroCoords/Position2D" (according to STC-1.30)
- removed restricted list of attribute "coord_system_id" in "AstroCoords": previous type=idValues (removed), new type=xs:string
- added "TimeInterval" of type "TimeInterval" in "Time"
- added "TimeOrigin" of type "xs:string" in "TimeInstant"
- added "TimeInterval" type with "StartTime" and "StopTime" elements
- changed minOccurs attribute in "Position2D/Error2Radius": now set to 0
- added "Error2" element in "Position2D" with type "error2" and minOccurs=0
- added "Error3" element in "Position3D" with type "error3" and minOccurs=0
- added "coord_value" type introducing "ucd" and "unit" attributes for C1, C2 and C3 elements
- added "error2" type, with "C1" and "C2" elements
- added "error3" type, with "C1", "C2" and "C3" elements
- added "TimeFrameType" (taken from to STC-1.30)
- added "SpaceFrameType" (taken from to STC-1.30)

The presentations of Pierre Le Sidaner at the last 2 interop meetings contain the rationale for the changes, but we can prepare a more detailed document, if we decide to proceed.

Sincerely
Baptiste Cecconi