path: root/lib/snmp/doc/src/snmpa_mib_data.xml

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  <header>
    <copyright>
      <year>2013</year><year>2016</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at
 
          http://www.apache.org/licenses/LICENSE-2.0

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      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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    </legalnotice>

    <title>snmpa_mib_data</title>
    <prepared></prepared>
    <docno></docno>
    <date></date>
    <rev></rev>
    <file>snmpa_mib_data.xml</file>
  </header>

  <module>snmpa_mib_data</module>
  <modulesummary>Behaviour module for the SNMP agent mib-server 
  data module.</modulesummary>
  <description>
    <p>This module defines the behaviour of the SNMP agent mib-server 
    data module. A <c>snmpa_mib_data</c> compliant module 
    must export the following functions: </p>
    <list type="bulleted">
      <item>
	<seealso marker="#new">new/1</seealso>
      </item>
      <item>
	<seealso marker="#close">close/1</seealso>
      </item>
      <item>
	<seealso marker="#sync">sync/1</seealso>
      </item>
      <item>
	<seealso marker="#load_mib">load_mib/4</seealso>
      </item>
      <item>
	<seealso marker="#unload_mib">unload_mib/4</seealso>
      </item>
      <item>
	<seealso marker="#lookup">lookup/2</seealso>
      </item>
      <item>
	<seealso marker="#next">next/3</seealso>
      </item>
      <item>
	<seealso marker="#register_subagent">register_subagent/3</seealso>
      </item>
      <item>
	<seealso marker="#unregister_subagent">unregister_subagent/2</seealso>
      </item>
      <item>
	<seealso marker="#which_mib">which_mib/2</seealso>
      </item>
      <item>
	<seealso marker="#which_mibs">which_mibs/1</seealso>
      </item>
      <item>
	<seealso marker="#whereis_mib">whereis_mib/2</seealso>
      </item>
      <item>
	<seealso marker="#dump">dump/2</seealso>
      </item>
      <item>
	<seealso marker="#info">info/1</seealso>
      </item>
      <item>
	<seealso marker="#backup">backup/2</seealso>
      </item>
      <item>
	<seealso marker="#code_change">code_change/4</seealso>
      </item>
    </list>

    <p>The semantics of them and their exact signatures are 
    explained below. </p>

    <p>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, <c>snmpa_mib_data_tttn</c> for details. </p>

  </description>

  <section>
    <title>CALLBACK FUNCTIONS</title>
    <p>The following functions must be exported from a 
    <c>mib-server</c> data callback module: </p>

    <marker id="new"></marker>
  </section>

  <funcs>
    <func>
      <name>Module:new(Storage) -> State</name>
      <fsummary>Create new (mib-server) data instance</fsummary>
      <type>
        <v>Storage = mib_storage()</v>
        <v>State = term()</v>
      </type>
      <desc>
        <p>Create a new mib-server data instance. </p>

        <marker id="close"></marker>
      </desc>
    </func>

    <func>
      <name>Module:close(State) -> void()</name>
      <fsummary>Close the mib-server data instance</fsummary>
      <type>
        <v>State = term()</v>
      </type>
      <desc>
        <p>Close the mib-storage.</p>

        <marker id="sync"></marker>
      </desc>
    </func>

    <func>
      <name>Module:sync(State) -> void()</name>
      <fsummary>Synchronize to disc</fsummary>
      <type>
        <v>State = term()</v>
      </type>
      <desc>
        <p>Synchronize (write to disc, if possible) the mib-server data. 
	This depends on the <c>mib_storage</c> 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). </p>

        <marker id="load_mib"></marker>
      </desc>
    </func>

    <func>
      <name>Module:load_mib(State, Filename, MeOverride, TeOverride) -> {ok, NewState} | {error, Reason}</name>
      <fsummary>Load a mib into the mib-server</fsummary>
      <type>
        <v>State = NewState = term()</v>
        <v>Filename = filename()</v>
        <v>MeOverride = boolean()</v>
        <v>TeOverride = boolean()</v>
        <v>Reason = already_loaded | term()</v>
      </type>
      <desc>
        <p>Load the mib specified by the <c>Filename</c> argument 
	into the mib-server. 
	The <c>MeOverride</c> and <c>TeOverride</c> arguments 
	specifies how the mib-server shall handle duplicate mib- and trap-
	entries. </p>

        <marker id="unload_mib"></marker>
      </desc>
    </func>

    <func>
      <name>Module:unload_mib(State, Filename) -> {ok, NewState} | {error, Reason}</name>
      <fsummary>Unload mib from the mib-server</fsummary>
      <type>
        <v>State = NewState = term()</v>
        <v>Filename = filename()</v>
        <v>Reason = not_loaded | term()</v>
      </type>
      <desc>
        <p>Unload the mib specified by the <c>Filename</c> argument 
	from the mib-server. </p>

        <marker id="lookup"></marker>
      </desc>
    </func>

    <func>
      <name>Module:lookup(State, Oid) -> Reply</name>
      <fsummary>Find the mib-entry corresponding to the Oid</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = {variable, ME} | {table_column, ME, TEOid} | {subagent, SAPid, SAOid} | {false, Reason}</v>
        <v>Oid = TEOid = SAOid = oid()</v>
        <v>SAPid = pid()</v>
        <v>ME = me()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Find the mib-entry corresponding to the <c>Oid</c>. 
	If it is a variable, the <c>Oid</c> must be 
	&lt;Oid for var&gt;.0 
	and if it is a table, <c>Oid</c> must be 
	&lt;table&gt;.&lt;entry&gt;.&lt;col&gt;.&lt;any&gt;.</p>

        <marker id="next"></marker>
      </desc>
    </func>

    <func>
      <name>Module:next(State, Oid, MibView) -> Reply</name>
      <fsummary>Finds the lexicographically next oid</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = false | endOfTable | {subagent, SAPid, SAOid} | {variable, ME, VarOid} | {table, TableOid, TableRestOid, ME}</v>
        <v>Oid = SAOid = VarOid = TableOid = TableRestOid = oid()</v>
        <v>SAPid = pid()</v>
        <v>ME = me()</v>
      </type>
      <desc>
        <p>Finds the lexicographically next oid. </p>

        <marker id="register_subagent"></marker>
      </desc>
    </func>

    <func>
      <name>Module:register_subagent(State, Oid, Pid) -> Reply</name>
      <fsummary>Register the subagent</fsummary>
      <type>
        <v>State = NewState = term()</v>
        <v>Reply = {ok, NewState} | {error, Reason}</v>
        <v>Oid = oid()</v>
        <v>Pid = pid()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Register the subagent, process, 
	handling part of the mib-tree. </p>

        <marker id="unregister_subagent"></marker>
      </desc>
    </func>

    <func>
      <name>Module:unregister_subagent(State, PidOrOid) -> Reply</name>
      <fsummary>Unregister the subagent</fsummary>
      <type>
        <v>State = NewState = term()</v>
        <v>Reply = {ok, NewState} | {ok, NewState, Pid} | {error, Reason}</v>
        <v>PidOrOid = pid() | oid()</v>
        <v>Pid = pid()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Unregister the subagent, handling part of the mib-tree, 
	as specified by the <c>oid()</c> or <c>pid()</c> 
	(<c>PidOrOid</c>). </p>
        <p>When unregister the subagent using an <c>oid()</c>, the <c>pid()</c> 
	of the process handling the sub-tree is also returned. </p>

        <marker id="dump"></marker>
      </desc>
    </func>

    <func>
      <name>Module:dump(State, Destination) -> Reply</name>
      <fsummary>Unregister the subagent</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = ok | {error, Reason}</v>
        <v>Destination = io | filename()</v>
        <v>Pid = pid()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Dump the mib-server data to <c>stdio</c> (Destination = <c>io</c>) or
	the specified file. </p>

        <marker id="which_mib"></marker>
      </desc>
    </func>

    <func>
      <name>Module:which_mib(State, Oid) -> Reply</name>
      <fsummary>Retrieve the mib file for an oid()</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = {ok, MibFile} | {error, Reason}</v>
        <v>Oid = oid()</v>
        <v>MibFile = string()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Retrieve the mib-file to which an given <c>oid()</c> belongs. </p>

        <marker id="which_mibs"></marker>
      </desc>
    </func>

    <func>
      <name>Module:which_mibs(State) -> Reply</name>
      <fsummary>Retrieve all loaded mib files</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = [{MibName, Filename}]</v>
        <v>MibName = atom()</v>
        <v>Filename = string()</v>
      </type>
      <desc>
        <p>Retrieve all loaded mib-files. </p>

        <marker id="whereis_mib"></marker>
      </desc>
    </func>

    <func>
      <name>Module:whereis_mib(State, MibName) -> Reply</name>
      <fsummary>Retrieve the mib file for the mib</fsummary>
      <type>
        <v>State = term()</v>
        <v>MibName = atom()</v>
        <v>Reply = {ok, Filename} | {error, Reason}</v>
        <v>Filename = string()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Retrieve the mib file for the mib. </p>

        <marker id="info"></marker>
      </desc>
    </func>

    <func>
      <name>Module:info(State) -> Reply</name>
      <fsummary>Retrieve misc info for the mib data</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = {ok, Filename} | {error, Reason}</v>
        <v>Filename = string()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Retrieve misc info for the mib data. </p>
        <p>This is a utility function used to inspect, for instance, 
	memory usage, in a simple way. </p>

        <marker id="backup"></marker>
      </desc>
    </func>

    <func>
      <name>Module:backup(State, BackupDir) -> Reply</name>
      <fsummary>Perform a backup of the mib-server data</fsummary>
      <type>
        <v>State = term()</v>
        <v>Reply = ok | {error, Reason}</v>
        <v>BackupDir = string()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Perform a backup of the mib-server data. </p>
        <p>Note that its implementation dependant (and also 
	dependent on mib-storage is used) if a backup is possible. </p>

        <marker id="code_change"></marker>
      </desc>
    </func>

    <func>
      <name>Module:code_change(Destination, Vsn, Extra, State) -> NewState</name>
      <fsummary>Perform a code-change</fsummary>
      <type>
        <v>Destination = up | down</v>
        <v>Vsn = term()</v>
        <v>Extra = term()</v>
        <v>State = NewState = term()</v>
      </type>
      <desc>
        <p>Perform a code-change (upgrade or downgrade). </p>
        <p>See 
	<seealso marker="stdlib:gen_server">gen_server</seealso>
	for more info regarding the <c>Vsn</c> and <c>Extra</c> arguments. </p>

      </desc>
    </func>

  </funcs>
  
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