Local catalogs can be accessed directly on the local system. They may have - but do not require - an entry in a catalog config file, since you can simply specify the file path name as the name of the catalog.
If the URL given for a catalog in the config file is the name of a local command, the command will be executed and should write query results in tab table format, as described above, on the stdout. Before executing the command, variables, such %ra, %dec or %x, %y (see below) are substituted by the catalog library to form the command string.
The first thing to do to make a catalog available over the net via the catalog library is to write an HTTP cgi-bin application to access the catalog. This application receives it's arguments from the environment variable QUERY_STRING, forms the query to send to the underlying database and then formats the results in tab table format before writing them on the stdout. The catalog library performs variable substitution (%ra, %dec, etc., see below) on the URL before sending it to the server.
Besides the column headings and the data, the query result may contain the catalog config entry, or parts of it, to indicate, for example, the locations of the RA and DEC columns or the symbols to plot.
Please send questions or comments to abrighto@eso.org@eso.org.
Copyright © 1998 ESO - European Southern Observatory