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 dependant (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.