NAME

       alarm_handler - An Alarm Handling Process

DESCRIPTION

       The  alarm  handler  process is a gen_event event manager process which receives alarms in
       the system. This process is not intended to be a complete  alarm  handler.  It  defines  a
       place  to  which  alarms  can  be sent. One simple event handler is installed in the alarm
       handler at start-up, but users are encouraged to write and install their own handlers.

       The simple event handler sends all alarms as info reports to the error logger,  and  saves
       all  of  them  in a list which can be passed to a user defined event handler, which may be
       installed at a later stage. The list can grow large if many alarms are generated. So it is
       a good reason to install a better user defined handler.

       There are functions to set and clear alarms. The format of alarms are defined by the user.
       For example, an event handler for SNMP could be defined, together with an alarm MIB.

       The alarm handler is part of the SASL application.

       When writing new event handlers for the  alarm  handler,  the  following  events  must  be
       handled:

         {set_alarm, {AlarmId, AlarmDescr}}:
           This event is generated by alarm_handler:set_alarm({AlarmId, AlarmDecsr}).

         {clear_alarm, AlarmId}:
           This event is generated by alarm_handler:clear_alarm(AlarmId).

       The  default  simple  handler  is  called alarm_handler and it may be exchanged by calling
       gen_event:swap_handler/3 as gen_event:swap_handler(alarm_handler,  {alarm_handler,  swap},
       {NewHandler,  Args}). NewHandler:init({Args, {alarm_handler, Alarms}}) is called. Refer to
       gen_event(3erl) for further details.

EXPORTS

       clear_alarm(AlarmId) -> void()

              Types:

                 AlarmId = term()

              Clears all alarms with id AlarmId.

       get_alarms() -> [alarm()]

              Returns a list of all active alarms. This function can only be used when the simple
              handler is installed.

       set_alarm(alarm())

              Types:

                 alarm() = {AlarmId, AlarmDescription}
                 AlarmId = term()
                 AlarmDescription = term()

              Sets  an  alarm with id AlarmId. This id is used at a later stage when the alarm is
              cleared.

SEE ALSO

       error_logger(3erl), gen_event(3erl)