Title:                  Re-implement data tables update procedures
Person responsible:     Joe McMullin (jmcmulli@nrao.edu)
Originator of proposal: Wim Brouw (wim.brouw@csiro.au)
Exploders targeted:     aips2-developers
Time table:
        Date of issue:          2004 February 24
        Comments due:           2004 March    1         
        Revised proposal:       2004 March    3         
        Final comments due:     2004 March    10
        Decision date:          2004 March    17

Statement of goals:
-------------------

o To have the code updating the aips++ data tables in the standard version control
	tree
o To use the available error detection to ensure continuing operation after a 
	failed update
o To notify an operational entity automatically in the case of update failures
o To add the new IERS tables connected to the IAU2000 and IERS2003 resolutions
	and definitions

Background:
-----------

Currently the data update for the Measures related information (like IERS tables;
planetary ephemeris; reference frames definitions) is done with Glish scripts that
are part copies of older versions of the scripts in the standard code tree; part
calls to scripts in the code tree.
This has caused problems when:

o glish internals have changed, and tests of the code external to the standard
	code tree are not done
o the content of the tables as imported changed, and changes to the code have
	not been incorporated in the data system
o new tables have to be added
o ftp address of data changed, and the data system did not act and/or inform
	correctly on error status

Proposed changes:
-----------------

To implement the decision taken at the Angel Fire aips++ programmers meeting by:

o changing the automatic data update procedures to a single call to the version
	controlled scripts
o ensure that error returns of calls are recognized
o mail error logs and/or status automatically to operational responsible group
	(and only errors)

Alternatively; the current scripting implementation of the 'measuresdata' interface
could be replaced by a compiled program interface. The first point will then call
a program, not a script function. The last two points remain the same. In addition
to a re-write of the scripts into a compiled language, an ftp-interface module and 
an e-mail-interface module have to be provided in OS module.

Expected Impact:
----------------

Will greatly reduce the occurrence of problems by users in cases where changes 
in format of the data and in the data distribution occur by early recognition
of problems before end-users note it.

Changes in OS interface; compilers; scripting language etc will be handled as
part of the standard code tree, and be in place before problems are exported
to users.

Proposed documentation changes:

Update URM on measuresdata and add documentation on the scripts.