Hi Doug,
I'm afraid I didn't really understand your reply.
I saw SkyNode as the protocol, and ADQL as one of the input parameters. SkyNode specifies the methods and parameters that any data access service must provide. One of the input parameters to the query method is the query itself and ADQL is the format that that query is in.
I thought that DAL was meant to spec the protocols for data access and so thought SkyNode came under that remit. This might also allow the development of common approaches to the data/image/spectra access protocols.
> about more sophisticated query capabilities in the DAL
What was asking about were basic data access capabilities.
> services. In the meantime adding access to new classes of
> astronomical data such as spectra and time series is more
> productive. Nonetheless, you have a good point.
> Perhaps we should expand the future topics session and
> increase the emphasis on catalog access and query language
> integration into the DAL services.
I was posing the question. If image and spectra access are more important than data access, then fine. If not, we really ought to focus on getting the data access spec nailed down before the others. Again, if the decision of the two groups is that VOQL workgroup looks after the data access protocol while DAL looks after image and spectra access protocols that's also fine - as long as it is explicitly agreed and there's agreement on the common areas to ensure we get coherent protocols out of the two groups.
> DAL, there is no clear distinction between tabular and
> gridded data, so it would be a mistake to try to split the two.
What is tabular and what is gridded data and what is the (non-)difference?
> includes query portals, a major VO user interface.
I don't think the IVOA needs get involved in UIs.
> Hence I think it makes sense to have a separate group develop
> the query technology.
No problem with that. But the interface is a DAL issue - possibly delegated to the VOQL group if that is the decision.
> For the above reasons I think it makes sense to have separate
> DAL and VOQL working groups. The main issue is adding a
Definitely wasn't proposing any different there.
Cheers,
Tony.
> -----Original Message-----
> From: owner-architecture-at-eso.org
> [mailto:owner-architecture-at-eso.org] On Behalf Of Doug Tody
> Sent: 13 May 2004 21:03
> To: architecture-at-ivoa.net
> Subject: RE: Proposed agenda for DAL session at the May
> Interop meeting (fwd)
>
> This discussion of VOQL and DAL seems of broader interest so
> I am forwarding
> this to the architecture WG. Doug
>
>
> ---------- Forwarded message ----------
> Date: Thu, 13 May 2004 13:58:14 -0600 (MDT)
> From: Doug Tody <dtody-at-nrao.edu>
> To: Tony Linde <ael-at-star.le.ac.uk>
> Cc: masatoshi.ohishi-at-nao.ac.jp, 'Roy Williams' <roy-at-caltech.edu>
> Subject: RE: Proposed agenda for DAL session at the May
> Interop meeting
>
> Tony -
>
> You seem to be arguing for a larger presence for SkyNode+ADQL
> in the DAL WG agenda. I originally had it in at the same
> level as the other services but it was squeezed out by the
> interest in having a joint session with the UCD WG, plus all
> the current activity in this area has been happening in VOQL.
> DAL really needs a working ADQL before we can worry too much
> about more sophisticated query capabilities in the DAL
> services. In the meantime adding access to new classes of
> astronomical data such as spectra and time series is more
> productive. Nonetheless, you have a good point.
> Perhaps we should expand the future topics session and
> increase the emphasis on catalog access and query language
> integration into the DAL services.
>
> I agree that a generalized QL-based catalog search (SkyNode)
> is a high priority. The problem is the next step requires an
> advanced query lanaguge capability to address. Regarding
> DAL, there is no clear distinction between tabular and
> gridded data, so it would be a mistake to try to split the two.
> Similarly, the data query is a major part of the DAL services
> so we can't ignore this area either. DAL needs QL
> capabilities, but the major focus of DAL should be on
> integrating such technology (as with data modeling) to
> provide uniform data access services.
>
> It would seem that the area of query language and catalog
> queries is broader and deeper than just what is required for
> data access services. The full query language problem
> includes query portals, a major VO user interface.
> The generalized catalog access problem includes distributed
> queries and joins, and large scale queries, both of which are
> very hard problems.
> Hence I think it makes sense to have a separate group develop
> the query technology.
>
> For the above reasons I think it makes sense to have separate
> DAL and VOQL working groups. The main issue is adding a
> basic (nondistributed) SkyNode to the DAL services, and
> integrating query language capabilities into all the DAL
> services once this technology is sufficiently developed.
>
> - Doug
>
>
>
> On Thu, 13 May 2004, Tony Linde wrote:
>
> > Hi Doug & Masatoshi,
> >
> > The VOQL list have discussed the SkyNode protocol but it probably
> > belongs under DAL in the architecture. We ought to consider whether
> > there is some common interface from which SkyNode, SSA and
> SIA ought
> > to inherit. If we do keep the split as it is now, maybe we need to
> > rename the groups Image Access and Data Access.
> >
> > I think ownership of the standards should be resolved before the
> > Boston Interop and then driven forward at that meeting. I'm worried
> > that SkyNode might slip between the cracks while VOQL argues about
> > ADQL and DAL about SSA/SIA. Yet SkyNode is probably the
> most important
> > protocol we need right now.
> >
> > Cheers,
> > Tony.
> >
> > > -----Original Message-----
> > > From: owner-dal-at-eso.org [mailto:owner-dal-at-eso.org] On
> Behalf Of Doug
> > > Tody
> > > Sent: 13 May 2004 04:53
> > > To: dal-at-ivoa.net
> > > Subject: Proposed agenda for DAL session at the May
> Interop meeting
> > >
> > > Dear DAL folks -
> > >
> > > The Data Access Layer discussions will be held 08:30 -
> 12:00 Tuesday
> > > and Wednesday mornings, May 25-26, in Jefferson room 256. We may
> > > also try to have some smaller impromptu focus meetings during the
> > > week to work out details of the interfaces currently in the
> > > definition stage.
> > >
> > > What follows is a draft agenda for the DAL sessions with some
> > > suggested topics in each area. If you would like to
> suggest a new
> > > topic or contribute in any of these areas please let me
> know. Those
> > > of you who have actively worked to develop specific
> material in the
> > > past six months are encouraged to present the relevant
> topic. The
> > > time allocations will be determined later as the agenda is
> > > developed.
> > >
> > > Any comments or other suggestions are most welcome!
> > >
> > > - Doug
> > >
> > >
> > > 1. SSA, time series
> > > - Service classes
> > > - Query interface
> > > - SSA data model
> > > - Data representation (VOTable, FITS, XML, text)
> > >
> > > We are still working on the SSA interface and data
> model documents
> > > and hope to have these available in advance of the workshop.
> > >
> > > 2. SIA V1.1
> > > - General dataset metadata (identification, characterization)
> > > - Logical dataset identifer proposal (logical groupings)
> > > - Ranking proposal
> > > - UCD normalization is discussed separately; see below
> > > - Anything else?
> > >
> > > SIA V1.1 is a limited scope upgrade to the current
> interface.
> > > The goal
> > > is the bring the interface up to current standards
> and add some
> > > modest
> > > new capabilities.
> > >
> > > 3. UTYPE and UCD (Joint with UCD WG!)
> > > - When and how to use UCD, UTYPE
> > > - UCDs for SIA V1.1
> > >
> > > This topic has received a great deal of discussion
> over the past
> > > year.
> > > Maybe this time we can nail it down, at least as
> regards usage in
> > > SIA V1.1, and SSA, which will follow the same pattern.
> > >
> > > 4. Roadmap and Future Topics
> > > - Catalog access (plans for ADQL usage in DAL,
> updated catalog
> > > access)
> > > - Exanded image access capabilities
> > > - Interferometry and event data
> > > - Other
> > >
> > > What is required to support the applications we plan
> to build over
> > > the next year?
> > >
> > >
> >
> >
>
>
Received on 2004-05-13Z21:29:59