> ## 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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