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  <header>
    <copyright>
      <year>2004</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.
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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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    <title>snmpa_discovery_handler</title>
    <prepared></prepared>
    <responsible></responsible>
    <docno></docno>
    <approved></approved>
    <checked></checked>
    <date></date>
    <rev></rev>
    <file>snmpa_discovery_handler.xml</file>
  </header>
  <module>snmpa_discovery_handler</module>
  <modulesummary>Behaviour module for the SNMP agent discovery handler.</modulesummary>
  <description>
    <p>This module defines the behaviour of the agent discovery
      handler. A <c>snmpa_discovery_handler</c> compliant module 
      must export the following functions: </p>
    <list type="bulleted">
      <item>
        <p><seealso marker="#stage1_finish">stage1_finish/2</seealso></p>
      </item>
    </list>
    <p>The semantics of them and their exact signatures are explained
      below. </p>

     <marker id="stage1_finish"></marker>
  </description>

  <funcs>
    <func>
      <name>stage1_finish(TargetName, ManagerEngineID, ExtraInfo) -> ignore | {ok, usm_entry() | [usm_entry()]} | {ok, usm_entry() | [usm_entry()], NewExtraInfo}</name>
      <fsummary>Discovery stage 1 finish</fsummary>
      <type>
        <v>TargetName = string()</v>
        <v>ManagerEngineID = string()</v>
        <v>ExtraInfo = term()</v>
        <v>usm_entry() = tuple() compatible with usm.conf</v>
        <v>NewExtraInfo = term()</v>
      </type>
      <desc>
        <p>This function is called at the end of stage 1 of the 
          discovery process. It should return either the atom 
          <c>ignore</c> or <c>{ok, usm_entry() | [usm_entry()]}</c>. See 
          <seealso marker="snmp_agent_config_files#usm">usm_entry()</seealso>
          and 
          <seealso marker="snmpa_conf#usm_entry">usm_entry/13</seealso>
          for more info. </p>

        <p>If the function returns <c>ignore</c>, then it is assumed that 
          either: </p>
        
        <list type="bulleted">
          <item>The caller (of the discovery function) will make the 
             needed updates later. </item>
          <item>The callback function itself did the updates. </item>
        </list>

        <p>In either case, the agent will do nothing, but return
          the retrieved ManagerEngineID (see 
          <seealso marker="snmpa#discovery">discovery</seealso>
          for more info) and possible continue with stage 2 of 
          the discovery process. </p>

        <p>The <c>ExtraInfo</c> argument is passed on from the 
          <seealso marker="snmpa#discovery">discovery</seealso>
          function. </p>

        <p>This function may return an updated <c>NewExtraInfo</c> 
          that will be used in subsequent calls to the callback 
          functions. Intended for future use. </p>

        <p>The purpose of this function is to generate the usm-
          related security data needed for usm processing in the 
          agent. Specifically, updating the usmUserTable. </p>

        <p>When an <c>usm_entry()</c> tuple (or a list of such
          tuples) is returned, this data is then added to the 
          <c>usmUserTable</c> by the (master-) agent. </p>

        <p>When an <c>usm_entry()</c> tuple (or a list of such
          tuples) is returned, this data is then added to the 
          <c>usmUserTable</c> by the (master-) agent. </p>

        <note><p>Note that the function does not check if this entry 
          already exists. </p></note>

        <note><p>Note that this function is executed in the context of 
          the master-agent process. </p></note>

      </desc>
    </func>

  </funcs>
  
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