RWP04: Registry Replication

[Keith Noddle]

Thanks for the feedback Ray - much appreciated!

I think we're all converging on the model proposed by Tony which, to
paraphrase Ray, is the full-(specialist/limited)-(source/private) model.
I think this pretty much satisfies the points raise by Wil and Ray as
well as meeting most of the useful requirements I originally proposed.
I'll start work on the design and get something posted on the IVOA Wiki
for comment - I'm conscious of the need to get a presentation together
in short order for Cambridge!

The other major aspect of the RWP04 work is the development of a
registry query schema. Tony, Elizabeth and I have been working on
something similar(!) for AstroGrid and whilst we don't yet have schema,
we have a simple example XML query (below) upon which I would welcome
everyone's comments. We are looking into XQuery/XPath, but that might
not be appropriate for the current iteration of AstroGrid. Again, your
comments would be welcome.

Keith.

-- 

Keith Noddle			Phone:  +44 (0)116 223 1894
AstroGrid Technical Lead	Fax:    +44 (0)116 252 3311
Dept of Physics & Astronomy	Mobile: +44 (0)7721 926 461
University of Leicester		Email:  ktn at star.le.ac.uk
Leicester, UK   LE1 7RH		Web:    http://www.astrogrid.org

--------------------------------------------

If the query we are trying to satisfy can be expressed in pseudo-SQL as:

SELECT * FROM <registry> WHERE 
   (
      TYPE="white dwarf star" AND 
      (WAVELENGTH="optical" OR WAVELENGTH="uv") AND 
      (KEYWORD="BPM 16274" OR 
         KEYWORD="GD 50" OR 
         KEYWORD="HST photometric standards"
      )
   )

then one way of presenting this in XML is shown below

<query>
   <selectionSequence>
      <selection>
         <item>type</item>
         <value>white dwarf star</value>
      </selection>
      <operator>AND</operator>
      <selectionSequence>
         <selection>
            <item>wavelength</item>
            <value>optical</value>
         </selection>
         <operator>OR</operator>   
         <selection>
            <item>wavelength</item>
            <value>uv</value>
         </selection>
      </selectionSequence>
      <operator>AND</operator>
      <selectionSequence>
         <selection>
            <item>keyword</item>
            <value>BPM 16274</value>
         </selection>
         <operator>OR</operforator>   
         <selection>
            <item>keyword</item>
            <value>GD 50</value>
         </selection>
         <operator>OR</operator>   
         <selection>
            <item>keyword</item>
            <value>HST photometric standards</value>
         </selection>
      </selectionSequence>
   </selectionSequence>
</query>

This only requires 6 tags and is sufficiently flexible to cope with most
queries I can think of - but I'm not an astronomer...!