## 5 Appendix A

This section describes the interfaces involved in the operations and maintenance functions for EVA. As an example SNMP is used for managament interaction.

### 5.1 Interfaces

                             2
        ---------------------------------------------------
       |                                                   |
       v             -------          ----------           |
     ------         |       |        |   SNMP   |  6   ---------   3   --------
    |      |   5    |  EVA  |   4    |   EVA    | --> |instrum  | --> | SNMPEA |
    | Appl | -----> | (OTP) | -----> |  adapt.  |     |(appl (*)|  1  | (OTP)  |
    | (*)  |        |       |        | (OTP)    |     |         | <-- |        |
     ------         |       |        | - - - -  |      ---------   /   --------
                     ------- \       | EVA-MIB  |         1       /
                              \      | instrum  | <--------------/
                               \4     ----------
                                \
                                 \    ----------
                                  -> |   HTTP   |
                                     |   EVA    |
                                     |  adapt.  |
                                      ----------

The `(*)` marked blocks are in the application domain; the left-most is the actual application implementation, are the right-most is the instrumentation of the application.

There are several interfaces involved:

1
  From SNMPEA to instrumentation functions for the application. This interface is defined in SNMPEA. [e.g. table_func(get_next, RowIndex, Cols)]
2
  From instrumentation code to the resources. This interface is internal to the application, and may differ between applications.
3
  From instrumentation code for events and alarms to SNMPEA traps. This interface is defined in SNMPEA. [e.g. snmp:send_trap(Trap)]
4
  From EVA to the different adaptations. This interface is defined in EVA. [e.g. gen_event:notify(#alarm{})]
5
  From applications to EVA. This interface is defined in EVA. [e.g. eva:send_alarm(Name, Sender, ...)]
6
  From SNMP EVA to application instrumentation. This interface is defined in EVA. [e.g. board_failure(#alarm{})]

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