The OPENLOG intrinsic provides access to the User Logging
facility. When an application calls OPENLOG
for a currently running
logging process, the logging process builds the data structures which
are necessary to allow the application to record data in the logfile,
and a record is written to the logfile identifying the application.
If the logid is not valid or the specified User Logging
process is not running, an error will be returned.
The identification information in the OPENLOG record
can be used, by the
recovery program, to identify the records in the logfile,
which belong to the process it is trying to recover.
In order for the identification information to be useful for
recovery, the application must retain some information of its
own, particularly if the logfile will be accessed by more than
one user process.
It is recommended that the application have a separate
file to record such information as: user, group, and account
which is accessing the logfile (this can be obtained with the
WHO intrinsic); the pin# of the process accessing the
logfile (this can be obtained with the GETPROCID intrinsic);
the fully qualified file name of the current logfile and the
ASCII code of the logid (these can be obtained with the
LOGINFO intrinsic); the date and time that the logfile was
opened by the application (call the CALENDAR and CLOCK
intrinsics immediately following a successful call to OPENLOG).
How this information will be used will be explained in Chapter 6,
"Recovery".
