The newly written alert monitor (AM) registers interest in a set
of tables (as defined in table m_am). It waits for alerts to be fired on
any of these tables and then updates an entry in M_TIMESTAMP_TABLE 
as appropriate.

Alerts are pretty cool because they are transaction based, i.e. they 
only fired  after a commit is performed. So a multi-row update 
will only invoke one alert.

As agreed the experiments should poll  M_TIMESTAMP_TABLE, and make 
the appropriate read when a timestamp there changes.

For the moment:

select SYSTEM_NAME,TABLE_NAME,to_char(LAST_UPDATE,'dd-mon-yy hh24:mi:ss') 
from lepmeas.m_timestamp_table;

SYSTEM_NAME          TABLE_NAME           LAST_UPDATE
-------------------- -------------------- --------------------
COLLIMATORS          M_COL                14-mar-96 12:04:31
MODE                 M_MODE               14-mar-96 13:02:13
PAGE1                M_PAGE1_COMMENTS     14-mar-96 12:34:14
POWCON               PC_READING           14-mar-96 12:51:52


The AM is running (in the foreground on my machine). To test it
temporary update rights on M_COL, M_MODE, M_PAGE1_COMMENTS and PC_READING 
have been granted to L3, ALEPH, OPAL and DELPHI. Just try 
update lepmeas.m_col set timestamp = sysdate; commit; on any of these tables
and watch lepmeas.m_timestamp_table;