Information on Service 'BSDC-VO TAP service'
The BSDC-VO's TAP end point. The Table Access
Protocol (TAP) lets you execute queries against our database tables,
inspect various metadata, and upload your own data. It is thus the
VO's premier way to access public data holdings.
Tables exposed through this endpoint include: main from the magic schema, main from the whsp schema, columns, groups, key_columns, keys, schemas, tables from the tap_schema schema, main from the veritas_lc schema, main from the veritas schema, emptyobscore, obscore from the ivoa schema.
For a list of all services and tables belonging to this service's
resource, see Information on resource '__system__/tap'
Service Documentation
This service speaks TAP, a protocol designed to allow the exchange of
queries and data between clients (that's normally something running on your
computer) and servers (e.g., us).
You will want to use some sort of client to query TAP services;
examples for those include:
- TOPCAT (see in the "VO" menu)
- TAPHandle (following this link should bring you to a page
that lets you query this server) works completely within your
browser,
- the TAP shell, giving you a command line and powerful job chaining
facilities,
- the GAVO VOTable library, letting you embed TAP queries in
python programs
You can, in a pinch, use our service in an XML-enabled browser, too.
Under Overview, look for the bullet point on tap and
follow the link to "this service". Then, click on "New job..."
in the job list, enter your query, click "Set query", then
"Execute query". Reload the page you are redirected to now
and then to see when your job is finished, then retrieve the result.
The queries this service executes are written an a dialect of SQL called
ADQL. You need to learn it to use this service. See
our ADQL tutorial. Also do not miss the local examples.
By the way, for quick ad-hoc queries from within a browser,
our ADQL form service may be more convenient than TAP.
Also see the table metadata of the tables exposed here.
Issues
For information on our ADQL implementation, see the
ADQL service info.
While columns with xtype adql:POINT are correctly ingested into the
database, adql:REGION columns are left alone (i.e., they are
strings in the database). The reason for this behaviour is that
in order to infer a column type, one would have to inspect the
entire table up front.
If multiple output columns in a query would end up having the same name,
in the output VOTable they are disambiguated by appending underscores.
This is in violation of the specification, but since fixing it would
require rather intrusive changes into our software and it is not
clear why one should want to use names when they are not unique to begin
with, this will probably not be fixed.
Overview
You can access this service using:
-
tap --
the interface to this site's Table Access Protocol service. This protocol is best accessed using specialized clients or libraries. In such clients, you can find this service by its IVORN,
ivo://bsdc.icranet.org/tap, or access it by entering its base URL http://vo.bsdc.icranet.org/__system__/tap/run/tap directly. Using an XSL-enabled web browser you can, in a pinch, also operate the service without a specialized client.
This service is published as follows:
- Within the
set(s) ivo_managed with the renderer
availability
- Within the
set(s) ivo_managed with the renderer
capabilities
- Within the
set(s) with the renderer
examples
- Within the
set(s) ivo_managed with the renderer
tableMetadata
- Within the
set(s) ivo_managed,local with the renderer
tap
local means it is listed on our front page,
ivo_managed means
it has a record in the VO registry, gavo means it
is within GAVO's service registry.
VOResource XML (that's something exclusively for VO nerds)
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