eva_snmp_adaptation

MODULE

eva_snmp_adaptation

MODULE SUMMARY

An SNMP Adaptation to EVA

DESCRIPTION

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.

EXPORTS

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.

Instrumentation Functions for the OTP-EVA-MIB

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.

EXPORTS

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.

SEE ALSO

eva(3), eva_sup(3), gen_event(3), snmp(3)

AUTHORS

Martin Björklund - support@erlang.ericsson.se