<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>2004</year><year>2020</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

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.
    
    </legalnotice>

    <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 since="">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><seeerl marker="#stage1_finish">stage1_finish/2</seeerl></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 since="">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 
          <seeguide marker="snmp_agent_config_files#usm">usm_entry()</seeguide>
          and 
          <seeerl marker="snmpa_conf#usm_entry">usm_entry/13</seeerl>
          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 
          <seeerl marker="snmpa#discovery">discovery</seeerl>
          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 
          <seeerl marker="snmpa#discovery">discovery</seeerl>
          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>
  
</erlref>

