DAL 2010

[Patrick Dowler]

Now that summer is over I want to get some discussions going and make some 
progress in the DAL-WG. I encourage everyone with an interest in defining and 
implementing data access *and* in writing applications that use the data 
access services to contribute. Although we will have most of the discussions 
on this mailing list, I am looking into the plausibility of having some more 
specific discussions via telecon in order to make progress in key areas.

* Where are we now?

The Standing Committee on Science Priorities has outlined a few high priority 
science cases that we as a community need to tackle. 

First, the ObsTAP project is nearing completion. This is mainly a DM-WG 
project (ObsCore DM) but for use in a TAP service we need to define an 
extension schema so TAP services can advertise that they support this (and 
other) data models.

The next priority is to deliver services to support the SED science cases. 
This has already been identified to require the photometry data model (PhotDM) 
and is closely related to SSA; in the coming months we will need to study the 
science cases and determine what is required in DAL to expose this model and 
support the use cases. 

The final science use case that impacts DAL is for users to be able to search 
by list of sources and types of sources; this sounds like functionality that 
is available via TAP but likely requires wider implementation, additional 
content, and orchestrated use of multiple services.

We currently have several standards under development or being considered for 
update. Inconsistencies have been identified in SpecDM that require an update 
to the model and may require an update to the SSA specification. We also have 
several ongoing efforts that have been languishing (PQL, SIAv2), transfers from 
other groups (SimDAP), and several new proposals (simple event access, simple 
light curve access).

* priorities for DAL

- TAP (or DAL) extension schema
- possible SSA maintainence release (1.x?) when SpecDM changes are known
- new SSA (1.x or v2?) to support the SED science case
- SIAv2
- SimDAP
- understanding new ideas/proposals and where they fit in

There is not much to discuss here unless I inadvertently left something out. 
In a follow-up message, I will present a modest proposal for a roadmap of DAL 
activities (relatively short-term), which I am sure will prompt some 
discussion.

Once we have defined the various parts, I will re-organise the DAL-WG wiki 
pages to make them a useful point of coordination.

-- 

Patrick Dowler
Tel/Tél: (250) 363-0044
Canadian Astronomy Data Centre
National Research Council Canada
5071 West Saanich Road
Victoria, BC V9E 2M7

Centre canadien de donnees astronomiques
Conseil national de recherches Canada
5071, chemin West Saanich
Victoria (C.-B.) V9E 2M7