Minutes of Data Access Layer Parallel Sessions

Institute of Astronomy, Univ. Cambridge, May 12, 2003

Participants

DT	Doug Tody (Chair)
CA	Christophe Arviset
DB	David Berry
FB	Francois Bonnarel
MD	Markus Dolensky (Minutes)
PD	Pat Dowler 
PF	Pierre Fernique
MF	Mike Fitzpatrick
BH	Bob Hanisch
SCK	Sang Chul Kim
YSK	Young-Soo Kim
PL	Peter Lamb
PO	Pedro Osuna
CP	Clive Page
AS	Andre Schaaff
RS	Riccardo Smareglia
MT	Mike Taylor
NA	Nicholas Walton
NY	Naoki Yasuda


Timetable
1.	10.20 - 11.05		intro, scope
2. 	11.30 - 13.00		scope continued, what standards are needed
3.	14.00 - 15.30		goals, key issues, use cases
4.	16.00 - 17.30		experience report CDS [FB], priorities


see DT's slides for details
further slides from:
FB, MD

ad 1.
Agree on DAL scope
- [DT] how to include catalogs, spectra, etc.
- [MD] extend from images to other domains as suggested by SAO
- [PD] data provider delivers just content; isn't that sufficient?

ad 2.
assemble list of existing DAL prototypes
types of data to be supported
[PD] questions support for source catalogs? 
=> keep it: it may require simplified query mechanism though
- data model defines data types (images, spectra, ...) and is a driver of DAL architecture
- service granularity: multiple services (not just 1 big DAL service), or hierarchy of services
=> there should be several services 
- Do we need a 'data set' type? 
=> Yes, but low priority. It could be complicated to support it. 

ad 3.
Splitting protocol into one for images and spectra?
ToDo: Analyze whether we need separate protocols.
[PD] questions whether one service for each data type is the right approach?
=> relax this requirement

Priorities
1. SIA V1.1 (July)
2. Spectral Access, SED
3. SIA V2 (spectral data cubes ...); merge with spectra?
4. VO Std. Integration
1st steps for event, visibility data (metadata for raw data)

spectra: use cases/goals
- SED
- 1d spectra
- on the fly extraction of spectra

ad 4)
SIAP implementation at CDS
shortcomings:
- IDs
- compression flag
- availability vs. image delivery
- SIZE used for ROI as well as image size

[PO] protocols: how about sockets, Web service, grid service?

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For agenda item 'roadmap' there will be another meeting, Tue, May 13 at lunch time.