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This module implements an SNMP adaptation to basic EVA. The
MIB implemented by this adaptation is OTP-EVA-MIB. The MIB is
located in the directory mibs in the distribution.
The resources generate events and alarms using the API provided by EVA. They are not aware that the events and alarms are sent as SNMP traps to SNMP managers.
However, each trap to be sent must be defined in an SNMP MIB, and there must be instrumentation functions that translate the EVA events and alarms into SNMP traps. Normally, each event and alarm in the system is mapped onto one separate SNMP trap. This mapping is done by registration of the events. The following functions are available for the registration. They could be called when the corresponding MIB is loaded.
create_tables(Nodes) -> void()
Types:
Nodes = [node()]
This function creates the Mnesia tables required for the
eva_snmp_adaptation. Nodes is a list of nodes
where the tables should be replicated. This list of nodes
should specify the same nodes where the application EVA can
be run distributed, so that EVA always can have local
access to the tables.
This function should be called once when installing the EVA application in the system.
name2index(Name) -> {ok, Index} | undefined
Types:
Name = atom()
Index = integer()
Maps an event to the corresponding eventIndex value
for the event, as defined in the eventTable in
OTP-EVA-MIB.
register_alarms(Alarms) -> void()
Types:
Alarms = [{Name, Trap, Treatment, Community, Func}]
Name = Trap = atom()
Func = fun(#alarm) -> {ok, ObjOID, CauseOID,
SnmpVarbinds}
Treatment = none | snmpTrap
Community = string()
ObjOid = CauseOid = [integer()]
This function must be used to register an EVA alarm as an
SNMP alarm. It is used to associate each event with the
corresponding SNMP trap and an Erlang instrumentation
function which translates the #alarm into a trap. The
corresponding Trap must be defined in an SNMP MIB.
Treatment defines how this alarm is treated when
it is generated. If it is snmpTrap, it is sent to the
Community.
When the EVA alarm Name is generated by an
application, the adaptation calls Func(#alarm). The
purpose of the Func is to translate the Erlang record
#alarm into SNMP values. ObjOID is an OBJECT
IDENTIFIER representation of the #alarm.sender,
CauseOID is an OBJECT IDENTIFIER representation of
the #alarm.cause, and SnmpVarbinds is a list of
extra variable bindings for the trap. This list is as
defined for snmp:send_trap.
The alarm record is defined in eva.hrl,
available in the include directory in the
distribution.
register_events(Events) -> void()
Types:
Events = [{Name, Trap, Treatment, Community, Func}]
Name = Trap = atom()
Func = fun(#event) -> {ok, SnmpVarbinds}
Treatment = none | snmpTrap
Community = string()
This function must be used to register an EVA event as an
SNMP event. It is used to associate each event with the
corresponding SNMP trap and an Erlang instrumentation
function which translates the #event into a trap. The
corresponding Trap must be defined in an SNMP MIB.
Treatment defines how this event is treated when
it is generated. If it is snmpTrap it is sent to the
Community.
When the EVA event Name is generated by an
application, the adaptation calls Func(#event). The
purpose of the Func is to translate the Erlang record
#event into SNMP values. The SnmpVarbinds is
a list of extra variable bindings for the trap. This list
is as defined for snmp:send_trap.
The event record is defined in eva.hrl,
available in the include directory in the
distribution.
start_link() -> {ok, Pid} | {error, Reason}
Starts the EVA SNMP adaptation. This function can be used
to include the service in a supervisor. Normally, functions
in the supervisor eva_sup can be used instead.
The function create_tables/1 must be called
before the service is started.
An EVA adaptation is always implemented as a
gen_event handler. So is
eva_snmp_adaptation. But in order to
supervise this service from an ordinary supervisor, this
function creates a process that supervises the
gen_event handler.
In some cases, other adaptations may need access to the SNMP
specific data in EVA. To do this, the instrumentation functions
for the SNMP objects can be used. These instrumentation
functions takes the arguments and return the values defined in
the application snmp.
alarmTable(Op, RowIndex, Cols) -> InstrumRet
Instrumentation function for alarmTable. This
function assumes that access checks are made according to
the MIB, so it may crash if, for example, alarmClass
is set.
curAlarmTable(Op, RowIndex, Cols) -> InstrumRet
Instrumentation function for currentAlarmTable.
This function assumes that access checks are made according
to the MIB, so it may crash if, for example,
currentAlarmSeverity is set.
curAlarmLastTimeChanged(get) -> InstrumRet
Instrumentation function for currentAlarmLastTimeSent.
eventTable(Op, RowIndex, Cols) -> InstrumRet
Instrumentation function for eventTable. This
function assumes that access checks are made according to
the MIB, so it may crash if, for example, eventTrapName is set.
eva(3), eva_sup(3), gen_event(3), snmp(3)