Starlink Project
Starlink System Note 75.1

A.C. Davenhall

26 July 2000

Copyright © 2000 Council for the Central Laboratory of the Research Councils

Writing Catalogue and Image Servers for GAIA and CURSA


GAIA and CURSA can interrogate remote catalogues via the Internet to return lists of objects which satisfy a given criterion. GAIA can also extract images of a specified region of sky from remote databases. Similar facilities are also available in other packages, such as the ESO SkyCat image display tool and the Gemini observing tool. This functionality is achieved by having servers running on the remote systems which accept queries sent by GAIA etc, interrogate their local copies of the catalogues to find the data which satisfy the query and return them. The servers can communicate with GAIA etc. because the query is sent, and the results returned, in a standard format. This document describes how to write such servers.

Who Should Read this Document?

This document is aimed at programmers who intend to write servers which will provide catalogue and image data for GAIA etc.


I  Preface
 1 Introduction
 2 Further Reading
II  Tutorial Example: Creating a Simple Server
 3 Introduction
 4 Basics of Querying Remote Catalogues
 5 Obtaining Example Files
 6 Creating a Server
  6.1 Query string
  6.2 Results returned
  6.3 Installing and testing the server
  6.4 Modifying the server
 7 Creating a Configuration File
  7.1 URL query
  7.2 Installing and testing the configuration file
  7.3 Modifying the configuration file
 8 Carrying On
  8.1 Multiple catalogue servers
  8.2 Providing range queries
  8.3 Linked configuration files
  8.4 Handling queries which return no results
III  Reference Material
 9 Introduction
 10 The Configuration File
  10.1 Keywords
  10.2 Types of servers
  10.3 URL and query specification
  10.4 Coordinates, units and formats
  10.5 Range queries
  10.6 Plotting directives
   10.6.1 symbol-info
   10.6.2 Examples
   10.6.3 Inserting private Tcl procedures
  10.7 Checking a configuration file
 11 The Tab-Separated Table Format
  11.1 Special columns of identifiers and celestial coordinates
  11.2 Conventions for tables returned by ACL servers
  11.3 CURSA extensions
  11.4 MIME type
 12 Image Servers