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Saving and Restoring Objects (Channels)  

Facilities are provided by the AST library for performing input and output (I/O) with any kind of Object. This means it is possible to write any Object into various external representations for storage, and then to read these representations back in, so as to restore the original Object. Typically, an Object would be written by one program and read back in by another.

We refer to ``external representations'' in the plural because AST is designed to function independently of any particular data storage system. This means that Objects may need converting into a number of different external representations in order to be compatible with (say) the astronomical data storage system in which they will reside.

In this section, we discuss the basic I/O facilities which support external representations based on text. These are implemented using a new kind of Object--a Channel. We will examine later how to use other representations, based on FITS headers, for storing Objects. These are implemented using a more specialised form of Channel called a FitsChan ([*]).



 

next up previous
Next: The Channel Model
Up: AST A Library for Handling World Coordinate Systems in Astronomy
Previous: Merging FrameSets

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
30th April 2003
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2003 Central Laboratory of the Research Councils