DAL Working Group meeting in Cambridge
dtody at nrao.edu
Sat May 10 01:18:10 PDT 2003
A list of reading materials and an updated agenda for the DAL working
group has been posted on the IVOA Wiki at
See you all in Cambridge next week.
On Thu, 1 May 2003, Doug Tody wrote:
> VO Data Access Layer (DAL) Working Group
> IVOA, Cambridge, UK May 12-16 2003
> Hi Folks -
> We will have the kick-off meeting of the IVOA Data Access Layer (DAL)
> working group on Monday May 12 at the IVOA Interoperability meeting in
> Cambridge. The initial discussion will be followed by smaller breakout
> meetings throughout the week, with a wrap-up discussion in plenary session
> on Friday morning.
> The primary purpose of the DAL working group will be to define, over the
> next year or so, the initial set of IVOA standards for VO science data
> access. In the Cambridge meeting we will need to clarify the scope of our
> working group and develop a roadmap of our activities for the next year.
> This will include identifying what data access standards are needed, how
> these will interoperate with each other, and how these will integrate
> with the infrastructure being developed by the other working groups
> (registry, UCDs, data models, VOTable, etc.). A special topic, possibly
> for a subgroup, will be to discuss what should be included in the second,
> "IVOA" version of the simple image access protocol due out this summer.
> Our first item of business is to prepare an agenda for the meeting.
> ***Anyone who is interested in presenting any material at the meeting
> should contact the WG organizers immediately.*** Please contact either
> myself (dtody at nrao.edu) or Markus Dolensky (Markus.Dolensky at eso.org),
> who is helping to organize the working group. We can't promise anything
> at this point about presentations (it will depend upon the final agenda
> and the time available) but we do want to benefit from our collective
> experiences in preparing these standards. Suggestions for agenda items
> or topics are also welcome.
> - Doug
> To help identify the areas where work is needed some thoughts on the
> scope of the VO data access layer follow.
> Scope of VO Data Access Layer
> The scope of the VO Data Access Layer includes the services and protocols
> used to access remote science data via the VO, as well as the software
> used to implement data access services. Ultimately this will include
> advanced capabilities such as data subsetting, data model mediation,
> and server-side analysis, i.e., for grid computing. We must also include
> some client-side software to demonstrate an end-user analysis capability
> and perform end-to-end testing and integration. Ultimately most analysis
> software will come from the user community, not from VO. DAL builds upon
> and integrates other VO technology for metadata, data models, data formats,
> registries, and queries.
> The science data dealt with by the DAL potentially includes all of the
> e.g., object catalogs
> Catalog analysis is a fundamental VO capability which is beyond
> the scope of mere data access, but at the DAL level catalog
> and image/spectra access are often performed together.
> e.g., 2D sky images
> data cubes
> e.g., 2D sky images with a spectral axis
> spectra, SEDs
> mainly 1D spectra
> 2D/longslit spectra? (maybe not right away)
> time series
> e.g., time-resolved photometry
> spectrally-resolved light curves
> synoptic imagery (e.g., all-sky camera, synoptic surveys)
> event list (photon counting) data
> visibility data (interferometry)
> The highest priority goes to object catalogs and 2D sky images, for which
> prototype data access services are already available. Spectral data cubes
> are probably best treated as a general type of image. Next in priority
> are spectra, especially simple 1D spectra; spectra are a high priority for
> the next phase of DAL development. Time series data is less common but is
> similar to 1D spectra and could possibly benefit from a similar approach.
> It would be useful to integrate event list data and visibility data into
> the VO, although our expectation is that most VO users will be interested
> in images produced from such data rather than the original data (image
> generation may need to be on-the-fly since there is in general no one
> best way to produce images from event data or UV data).
> The highest priority for IVOA data access standards is probably in the area
> of standard data access protocols - this is what we should emphasize in
> the first year. Protocols are, or should be, implementation-independent
> and hence are one of these easiest software elements to standardize.
> As the VO software and infrastructure becomes more complicated it will
> become increasingly important to provide some reusable VO framework-level
> software to simplify the job of those putting up services or writing
> client-side applications. Finally as we move to grid computing it will
> become necessary to dynamically deploy computational components on any
> grid-enabled computational resource. For this to be feasible we will need
> some interoperability standards in the areas of computational frameworks
> and components.
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