snmpa_mib_data(3erl)

NAME
snmpa_mib_data - Behaviour module for the SNMP agent mib-server
  data module.

DESCRIPTION

This module defines the behaviour of the SNMP agent mib-server data module. A snmpa_mib_data compliant module must export the following functions:

    *   new/1

    *   close/1

    *   sync/1

    *   load_mib/4

    *   unload_mib/4

    *   lookup/2

    *   next/3

    *   register_subagent/3

    *   unregister_subagent/2

    *   which_mib/2

    *   which_mibs/1

    *   whereis_mib/2

    *   dump/2

    *   info/1

    *   backup/2

    *   code_change/4

The semantics of them and their exact signatures are explained below.

Note that the data extracted from the imported (loaded) mibs are stored partly by the mib-server and partly by the symbolic-store server. See the default mib-server data module, snmpa_mib_data_tttn for details.

CALLBACK FUNCTIONS

The following functions must be exported from a mib-server data callback module:

EXPORTS

Module:new(Storage) -> State

    Types:

        Storage = mib_storage()
        State = term()

    Create a new mib-server data instance.

Module:close(State) -> void()

    Types:

        State = term()

    Close the mib-storage.

Module:sync(State) -> void()

    Types:

        State = term()

    Synchronize (write to disc, if possible) the mib-server data. This depends on the mib_storage option, and will only have an effect if the mib-storage option has an actual disc component (such as dets, or ets with a file).

Module:load_mib(State, Filename, MeOverride, TeOverride) -> {ok, NewState} | {error, Reason}

    Types:

        State = NewState = term()
        Filename = filename()
        MeOverride = boolean()
        TeOverride = boolean()
        Reason = already_loaded | term()

    Load the mib specified by the Filename argument into the mib-server. The MeOverride and TeOverride arguments specifies how the mib-server shall handle duplicate mib- and trap- entries.

Module:unload_mib(State, Filename) -> {ok, NewState} | {error, Reason}

    Types:

        State = NewState = term()
        Filename = filename()
        Reason = not_loaded | term()

    Unload the mib specified by the Filename argument from the mib-server.

Module:lookup(State, Oid) -> Reply

    Types:

        State = term()
        Reply = {variable, ME} | {table_column, ME, TEOid} | {subagent, SAPid, SAOid} | {false, Reason}
        Oid = TEOid = SAOid = oid()
        SAPid = pid()
        ME = me()
        Reason = term()

    Find the mib-entry corresponding to the Oid. If it is a variable, the Oid must be <Oid for var>.0 and if it is a table, Oid must be <table>.<entry>.<col>.<any>.

Module:next(State, Oid, MibView) -> Reply

    Types:

        State = term()
        Reply = false | endOfTable | {subagent, SAPid, SAOid} | {variable, ME, VarOid} | {table, TableOid, TableRestOid, ME}
        Oid = SAOid = VarOid = TableOid = TableRestOid = oid()
        SAPid = pid()
        ME = me()

    Finds the lexicographically next oid.

Module:register_subagent(State, Oid, Pid) -> Reply

    Types:

        State = NewState = term()
        Reply = {ok, NewState} | {error, Reason}
        Oid = oid()
        Pid = pid()
        Reason = term()

    Register the subagent, process, handling part of the mib-tree.

Module:unregister_subagent(State, PidOrOid) -> Reply

    Types:

        State = NewState = term()
        Reply = {ok, NewState} | {ok, NewState, Pid} | {error, Reason}
        PidOrOid = pid() | oid()
        Pid = pid()
        Reason = term()

    Unregister the subagent, handling part of the mib-tree, as specified by the oid() or pid() (PidOrOid).

    When unregister the subagent using an oid(), the pid() of the process handling the sub-tree is also returned.

Module:dump(State, Destination) -> Reply

    Types:

        State = term()
        Reply = ok | {error, Reason}
        Destination = io | filename()
        Pid = pid()
        Reason = term()

    Dump the mib-server data to stdio (Destination = io) or the specified file.

Module:which_mib(State, Oid) -> Reply

    Types:

        State = term()
        Reply = {ok, MibFile} | {error, Reason}
        Oid = oid()
        MibFile = string()
        Reason = term()

    Retrieve the mib-file to which an given oid() belongs.

Module:which_mibs(State) -> Reply

    Types:

        State = term()
        Reply = [{MibName, Filename}]
        MibName = atom()
        Filename = string()

    Retrieve all loaded mib-files.

Module:whereis_mib(State, MibName) -> Reply

    Types:

        State = term()
        MibName = atom()
        Reply = {ok, Filename} | {error, Reason}
        Filename = string()
        Reason = term()

    Retrieve the mib file for the mib.

Module:info(State) -> Reply

    Types:

        State = term()
        Reply = {ok, Filename} | {error, Reason}
        Filename = string()
        Reason = term()

    Retrieve misc info for the mib data.

    This is a utility function used to inspect, for instance, memory usage, in a simple way.

Module:backup(State, BackupDir) -> Reply

    Types:

        State = term()
        Reply = ok | {error, Reason}
        BackupDir = string()
        Reason = term()

    Perform a backup of the mib-server data.

    Note that its implementation dependent (and also dependent on mib-storage is used) if a backup is possible.

Module:code_change(Destination, Vsn, Extra, State) -> NewState

    Types:

        Destination = up | down
        Vsn = term()
        Extra = term()
        State = NewState = term()

    Perform a code-change (upgrade or downgrade).

    See gen_server for more info regarding the Vsn and Extra arguments.