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ActiveSocket - SnmpTrapManager Object

An SNMP trap is simply a notification message that is transmitted by an SNMP-managed device whenever it has something of interest to report. Traps can be thought of as event messages, similar to the events in the Windows event logs. Traps, like regular SNMP variables, are defined in MIB (Management Information Base) files. They are defined as a set of SNMP variables contained in (or referenced by) an OID (Object Identifier). If you look at the system directory on any Windows machine that has SNMP installed, you will find several MIB files. (They have the extension ".mib".) If you look through them you will see the variables that are supported on that machine. ActiveSocket has interfaces for sending and receiving SNMP traps.

The SnmpTrapManager object provides properties and functions for sending and receiving SNMP traps. The SnmpTrap object provides enacapsulates all trap properties. It is used in onjunction with the SnmpTrapmanager object.

The ActiveSocket SnmpTrapManager and SnmpTrap objects are compliant with SNMP v1 and SNMP v2c. ActiveSocket automatically detects which SNMP version is running on the remote agent and adapts to it.

The ActiveSocket trap objects supports different data types, including:

  • String types (also called "octet strings");
  • Integer types (16bit, 32bit and unsigned integers);
  • IP Address types;
  • Timetick types;
  • Counter types (32bit and 64bit counters);
  • OID types (also called "Object ID's");
  • Other, less frequently used datatypes.

The ActiveSocket trap objects feature the following:

  • Support for SNMP v1 and SNMP v2c;
  • Support for aplphanumeric OID's (object identifier) and numeric OID's;
  • Multi-threading architecture: send SNMP traps simultaneously from one process using multiple threads;
  • Support for ports other than the default 161 and 162 ports;
  • Send multiple SNMP traps in one SNMP message;

Overview of all ActiveSocket objects:

SnmpTrapManager Sample code

Visual Basic .NET sample: Send SNMP traps

Imports ASOCKETLib

Module SendTrap
   Sub Main()

      Dim objManager As SnmpTrapManager
      Dim objTrap As SnmpTrap
      Dim objSnmpObject As SnmpObject
      Dim objConst As SocketConstants

      objManager    = New SnmpTrapManager
      objTrap       = New SnmpTrap
      objSnmpObject = New SnmpObject
      objConst      = New SocketConstants

      objManager.Initialize()

      objTrap.Host        = "server03"
      objTrap.Community   = "public"

      objSnmpObject.OID   = ".1.3.6.1.2.1.1.5.0"
      objSnmpObject.Type  = objConst.asSNMP_TYPE_IPADDRESS
      objSnmpObject.Value = "10.0.0.1"

      objTrap.AddObject(objSnmpObject)

      objManager.Send(objTrap)
      objManager.Shutdown()
    End Sub
End Module

Visual C# .NET: Receive SNMP traps

using System;
using ASOCKETLib;

namespace ReceiveTrap 
{
  class ReceiveTrap 
  {
    [STAThread]
    static void Main(string[] args) 
    {
      SnmpTrapManager  objManager = new SnmpTrapManager();
      SnmpTrap         objTrap;
      SnmpObject       objSnmpObject;

      objManager.Initialize();
      objManager.StartListening ( "public", 162 );
		
      while ( true ) 
      {
        objTrap = ( SnmpTrap ) objManager.GetFirstTrap();

        while( objManager.LastError == 0 ) 
        {
          objSnmpObject = ( SnmpObject ) objTrap.GetFirstObject ();
				
          while( objTrap.LastError == 0 ) 
          {
            Console.WriteLine( "OID   :" + objSnmpObject.OID );
            Console.WriteLine( "Value :" + objSnmpObject.Value );
            Console.WriteLine( "Type  :" + objSnmpObject.Type );
					
            objSnmpObject = ( SnmpObject ) objTrap.GetNextObject ();
          }
					
          objTrap = ( SnmpTrap ) objManager.GetNextTrap();
        }
				
        System.Threading.Thread.Sleep ( 1000 );
      }

      objManager.StopListening(); 			
      objManager.Shutdown();
    }
  }
}

On ftp.activexperts-labs.com, you can find a lot of ActiveSocket samples. These samples are also part of the ActiveSocket installation.

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