.TH alarm_handler 3erl "sasl 3.0.2" "Ericsson AB" "Erlang Module Definition"
.SH NAME
alarm_handler \- An Alarm Handling Process
.SH DESCRIPTION
.LP
The alarm handler process is a \fB\fIgen_event\fR\&\fR\& event manager process that 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 startup, but users are encouraged to write and install their own handlers\&.
.LP
The simple event handler sends all alarms as info reports to the error logger, and saves all in a list\&. This list can be passed to a user-defined event handler, which can be installed later\&. The list can grow large if many alarms are generated\&. This is a good reason to install a better user-defined handler\&.
.LP
Functions are provided to set and clear alarms\&. The alarm format is defined by the user\&. For example, an event handler for SNMP can be defined, together with an alarm Management Information Base (MIB)\&.
.LP
The alarm handler is part of the SASL application\&.
.LP
When writing new event handlers for the alarm handler, the following events must be handled:
.RS 2
.TP 2
.B
\fI{set_alarm, {AlarmId, AlarmDescr}}\fR\&:
This event is generated by \fIalarm_handler:set_alarm({AlarmId, AlarmDecsr})\fR\&\&.
.TP 2
.B
\fI{clear_alarm, AlarmId}\fR\&:
This event is generated by \fIalarm_handler:clear_alarm(AlarmId)\fR\&\&.
.RE
.LP
The default simple handler is called \fIalarm_handler\fR\& and it can be exchanged by calling \fB\fIgen_event:swap_handler/3\fR\&\fR\& as \fIgen_event:swap_handler(alarm_handler, {alarm_handler, swap}, {NewHandler, Args})\fR\&\&. \fINewHandler:init({Args, {alarm_handler, Alarms}})\fR\& is called\&. For more details, see \fB\fIgen_event(3erl)\fR\&\fR\& in STDLIB\&.
.SH EXPORTS
.LP
.B
clear_alarm(AlarmId) -> void()
.br
.RS
.LP
Types:

.RS 3
AlarmId = term()
.br
.RE
.RE
.RS
.LP
Sends event \fIclear_alarm\fR\& to all event handlers\&.
.LP
When receiving this event, the default simple handler clears the latest received alarm with id \fIAlarmId\fR\&\&.
.RE

.LP
.B
get_alarms() -> [alarm()]
.br
.RS
.LP
Returns a list of all active alarms\&. This function can only be used when the simple handler is installed\&.
.RE

.LP
.B
set_alarm(alarm())
.br
.RS
.LP
Types:

.RS 3
alarm() = {AlarmId, AlarmDescription}
.br
AlarmId = term()
.br
AlarmDescription = term()
.br
.RE
.RE
.RS
.LP
Sends event \fIset_alarm\fR\& to all event handlers\&.
.LP
When receiving this event, the default simple handler stores the alarm\&. \fIAlarmId\fR\& identifies the alarm and is used when the alarm is cleared\&.
.RE

.SH "SEE ALSO"

.LP
\fB\fIerror_logger(3erl)\fR\&\fR\&, \fB\fIgen_event(3erl)\fR\&\fR\&