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How to migrate from AGENT++ 4.2.x (or older) to 4.3.0 (or newer) to be able to use multiple agents in a single process?

Version 1.1 by Frank Fock on 2024/05/25 09:55

In AGENT++ prior to 4.3.0, there were many MibEntry relations and the usage of the central Mib instance organised by static class members called "instance". Although this reduces code size and makes initialisation routines easier it makes it impossible to run more than one Mib instance in a process. 

In AGENT++ 4.3.0 this has been refactored by lot of internal changes, which had two main goals:

  1. Remove any Mib::instance usages that are not optional to the API user (i.e. backward compatibility can/should be provided)
  2. Remove any v3MP::I usages that are not optional to the API user.

If you do not want to use the multi-agent support, you do not have to change anything in your code. In case, you want to clean-up the API usage and/or want to use the new features, please follow the steps below in your agent application:

AGENT++ agent intialisation (+new/-old)
    Snmpx snmp(status, inaddr);
-   mib = new Mib(persistentObjectsPath);
+   mib = new Mib(persistentObjectsPath, path(bootCounterFile));
-   reqList = new RequestList();
+   reqList = new RequestList(mib);
    reqList->set_snmp(&snmp);
    mib->set_request_list(reqList);

    v3MP *v3mp = new v3MP(engineId, snmpEngineBoots, stat);
+   snmp.set_mpv3(v3mp);

-   mib.add(new snmp_community_mib());
+   mib.add(new snmp_community_mib(&mib));

-   mib.add(new agentpp_config_mib());
+   mib.add(new agentpp_config_mib(&mib));

-   mib.add(new notification_log_mib());
+   mib.add(new notification_log_mib(&mib));

+   snmpCommunityEntry* communityEntry = snmpCommunityEntry::get_instance(mib);
+   if (communityEntry) {
        OctetStr co("public");
-       MibTableRow* row = snmpCommunityEntry::instance->add_row(Oidx::from_string(co, FALSE));
+       MibTableRow* row = communityEntry->add_row(Oidx::from_string(co, FALSE));
        OctetStr tag("v1v2cPermittedManagers");
-       snmpCommunityEntry::instance->set_row(row, co, co,
+       communityEntry->set_row(row, co, co, reqList->get_v3mp()->get_local_engine_id(),"", tag, 3, 1);
+   }

-   UsmUserTable *uut = new UsmUserTable();
+   v3MP* v3mp = mib.get_request_list()->get_v3mp();
+   UsmUserTable *uut = new UsmUserTable(v3mp);
    // add non persistent USM statistics
-   mib.add(new UsmStats());
+   mib.add(new UsmStats(v3mp));
    // add the USM MIB - usm_mib MibGroup is used to
    // make user added entries persistent
    mib.add(new usm_mib(uut));
    // add non persistent SNMPv3 engine object
-   mib.add(new V3SnmpEngine());
-   mib.add(new MPDGroup());
+   mib.add(new V3SnmpEngine(v3mp));
+   mib.add(new MPDGroup(v3mp));