Hi All -
As part of the "TAP/Param" effort we surveyed some existing table query interfaces representing current practice of large astronomical data centers (these are production interfaces in daily use, not prototypes). These are interesting to study to see what is the current practice and what works for users. I append some notes and links below.
These cases all represent the simple parameter-type interface, which is what is needed for most simple end-user use to query individual astronomical catalogs (which represents most user research-oriented table access in astronomy). Where we need ADQL/VOSpace/async etc. (and we do) is to support more sophisticated analysis software, and to federate resources at data centers to be able to do large scale cross matches and the like - currently this is done at a few places, but it is done on a site specific basis with proprietary software. Both of these use cases are essential, and there is no reason that TAP can't support both.
Study of Existing Data Center Table Access Interfaces
The remainder of this document summarizes the existing interfaces to several major data centers (CDS, IRSA, HEASARC), all of which are HTTP GET and parameter based.
CDS ASU Syntax/Capabilities
Syntax
-option query option or parameter
field field name
Parameters
source catalog or data source (multiple catalogs permitted)
sql url-encoded SQL expression
c ra{+-}dec|objname, c.eq=equinox, c.epoch,
c.rm=[min/]max, c.bm=x[/y]
mime output format
(html,fits,tsv,text,gif,jpeg,starbase,ps,pdf,...)
out list of fields to be returned (also "all", "basic"
out.max maximum number of output fields
out.next to step through large queries (server dependent)
out.object return only object identification (name, ra, dec)
oc coordinate frame for output coordinates
sort sort by field[,field[,...]]
resolv which name resolver to use (ned, simbad)
Features
Multiple catalogs can be queried (union of results is the default)
Query by position is a special case
Supports query by name or position
Can input coords in sexagesimal notation
Variety of time stds for equinox and epoch
Radius includes both min and max values
Box search rectangle tan projection aligned with frame (undef at poles)
Frame is specified with the equinox
Can specify coordinate output format
Can specify sort order of output table
Numeric Query Constraint Operators
= != >= <= < > equality, less than, greater
.. numeric range
& | AND/OR, e.g., "1..5 & 7..9"
, list of values
! NOT (logical)
null Unspecified/blank value
now For DATE comparisons
JDnnn Julian date (otherwise UT)
Character Query Constraint Operators
~ Caseless pattern matching (default, wildcards)
= Pattern matching (wildcards)
=~ Caseless equality
== Strict equality
! !~ != NOT of pattern matching, caseless PM, strict equality
> >= < <= Alphabetical comparisons
Pattern matching supports [<set>], [^<set>] (NOT of set), *, ?
Examples
http://host_name/cgi_path?-sql=select%20distinct%20name%20from%20table
IRSA Gator Syntax/Capabilities
Syntax
only simple parameters
URL encoding can use "+" to replace a space
+/- used to delimit RA DEC pairs
Parameters
spatial Type of spatial query (Cone,Box,Polygon,NONE)
polygon Convex polygon, ra dec pairs, comma delimited
radius Cone search radius (default 10 arcsec)
radunits Units cone search (arcsec, arcmin, deg; default arcsec)
size Width of a Box in arcsec
objstr Target name or coordinate of center of spatial region
catalog Catalog name as defined by IRSA
outfmt 3=VOTable, 2=SVC msg, 1=ASCII table, 0=HTML (default)
desc Pass-through description of catalog for result page
order Sort output by this column
constraint SQL WHERE clause
onlist Used to get at new catalogs for testing
selcols Columns to be returned
outrows Number of output rows
Features
CatQuery Query a given catalog
CatList List of catalogs (XML or HTML)
supports region queries, SQL queries
CatDD List the fields of a catalog (XML or HTML)
default columns or all columns
can use this in a UI to build a query
description, units, index, DBType
support MULTI-OBJECT SEARCH
Numeric Query Constraint Operators
Uses SQL
Character Query Constraint Operators
Uses SQL
Examples
http://.../Gator/nph-query?
outfmt=1&objstr=m31&spatial=Cone&catalog=fp_psc
http://.../Gator/nph-query?
outfmt=1&objstr=10.68469+41.26904&spatial=Cone&
radius=1&radunits=arcsec&catalog=fp_psc
http://.../Gator/nph-query?
outfmt=1&order=j_m&objstr=m31&spatial=Polygon&
polygon=10.1+10.1,10.0+10.1,10+10&catalog=fp_psc
http://.../Gator/nph-query?
outfmt=2&objstr=m31&spatial=Box&catalog=fp_psc&
selcols=ra,dec,j_m,h_m,k_m&size=10
HEASARC CGI Syntax/Capabilities
Syntax
Same as "browse" web interface
>5000, 4..10, 3C*273, etc.
Parameters
table Table name (mandatory)
position Object name or position
coordinates Spatial frame ("equatorial" or "galactic")
equinox Equinox for equatorial coordinates (default 2000)
radius Radius for search in arcmin (def 60)
fields "standard", "all", or comma-delim list of fields
name_resolver NED or Simbad
infile For multi-object searches; each line is a "position"
outfile Save results to a file (for Perl script)
format HTML, FITS, EXCEL, VOTable, Text
sortvar Sort field
param "param=name,value" (or "name=value")
Features
Positions support multiple values delimited by semicolons
Numeric Query Constraint Operators
Character Query Constraint Operators
Examples
browse_extract.pl table=rospublic position=3c273 name_resolver=ned Received on 2008-05-15Z23:32:36