Java Dynamic Management Kit 5.1 Tutorial

16.5 Multiple Agents

It is possible to create multiple SNMP agents in the Java virtual machine (JVM). A multiple agent is an agent that instantiates more than one SNMP adaptor server. This enables you to create multiple SNMP MIBs using that agent, with each MIB having its own individual security configuration. The main advantage of this is to reduce the burden on the JVM.

You can create multiple agents using all three versions of SNMP. However, the multiple agent demonstrated in the following example is an SNMPv3 agent that creates and registers two SNMP adaptor servers in the MBean server. Registration in the MBean server enables the MIBs generated to be managed through the HTML adaptor.

Example 16–10 MultipleAgentV3 Example

public class MultipleAgentV3 {

    static SnmpV3AdaptorServer snmpAdaptor1 = null;
    static SnmpV3AdaptorServer snmpAdaptor2 = null;
	   //Set the number of traps
    private static int nbTraps = -1;

	  public static void main(String args[]) {
        		MBeanServer server;
       		ObjectName htmlObjName;
        		ObjectName snmpObjName1;
				   ObjectName snmpObjName2;
        		ObjectName mibObjName1;
				   ObjectName mibObjName2;
        		ObjectName trapGeneratorObjName;
        		int htmlPort = 8082;
        		// Initialize trace property.

	          // Create and start the HTML adaptor.
            // Create and start the first SNMP adaptor.
            int snmpPort = 8085;
            snmpObjName1 = new ObjectName(domain + 
						+ snmpPort);
            snmpAdaptor1 = new SnmpV3AdaptorServer(snmpPort);
            server.registerMBean(snmpAdaptor1, snmpObjName1);
	   			snmpAdaptor1.registerUsmMib(server, null);

            // Send a coldStart SNMP Trap. 
            // Use port = snmpPort+1.
            print("NOTE: Sending a coldStart SNMP trap"+
		  		" to each destination defined in the ACL file...");
            snmpAdaptor1.setTrapPort(new Integer(snmpPort+1));
            snmpAdaptor1.snmpV1Trap(0, 0, null);
	    		// Create and start the second SNMP adaptor.
				snmpPort = 8087;
          	snmpObjName2 = new ObjectName(domain + 
                 ":class=SnmpAdaptorServer,protocol=snmp,port=" + snmpPort);
            Trace.send(Trace.LEVEL_TRACE, Trace.INFO_MISC, "Agent", "main", 
                       "Adding SNMP adaptor to MBean server with name \n\t"+
            println("NOTE: SNMP Adaptor is bound on UDP port " + snmpPort);

	    		// Instantiate second adaptor instantiation.
				SnmpEngineParameters params = new SnmpEngineParameters();

	    		//Create the adaptor passing it the parameters.
            snmpAdaptor2 = new SnmpV3AdaptorServer(params,
            server.registerMBean(snmpAdaptor2, snmpObjName2);
	    		snmpAdaptor2.registerUsmMib(server, null);

            // Send a coldStart SNMP Trap.
            // Use port = snmpPort+1.
       	    print("NOTE: Sending a coldStart SNMP trap"+
				 " to each destination defined in the ACL file...");
            snmpAdaptor2.setTrapPort(new Integer(snmpPort+1));
            snmpAdaptor2.snmpV1Trap(0, 0, null);

          	// Create the first and second instances of MIB II   
	  			// (RFC 1213) and add them  to the MBean server.
            mibObjName1 = new ObjectName("snmp:class=RFC1213_MIB");
            mibObjName2 = new ObjectName("snmp:class=RFC1213_MIB_2");
            // Create 2 instances of the customized MIB
            RFC1213_MIB mib2 = new RFC1213_MIB_IMPL();

	    	    RFC1213_MIB mib2_2 = new RFC1213_MIB_IMPL("RFC1213_MIB_2");
            server.registerMBean(mib2, mibObjName1);
	    		server.registerMBean(mib2_2, mibObjName2);
            // Bind the SNMP adaptor to the MIB in order to make the MIB 
	    		mib2.setSnmpAdaptor(snmpAdaptor, "TEST-CONTEXT");
	    		mib2_2.setSnmpAdaptor(snmpAdaptor2, "TEST-CONTEXT");
	    //Multiple agent is ready to answer SNMP requests.

        } catch (Exception e) {


This example creates an MBean server as normal, and creates and registers an HTML adaptor in the MBean server, again in the same way as was done in the simple agent example. However, MultipleAgentV3 then creates and registers two SNMP adaptor servers in the MBean server. The two SNMP adaptors are bound to non-standard SNMP ports, in this case ports 8085 and 8087.

Each adaptor generates MIBs from its own security file, enabling you to have different, and remotely updatable, security configurations for each SNMP adaptor server. The first SNMP adaptor server, snmpAdaptor1, gets its security configuration from the security file when the agent is started. The second SNMP adaptor server, snmpAdaptor2, gets its security configuration from a second security file,, using the params.setSecurityFile method. You can consult in the examplesDir/current/Snmp/Agent directory. Both these security files implement authentication without privacy.

Caution – Caution –

The coherency of the file is not preserved if you use the same file for more than one adaptor server.

16.5.1 Running the SNMPv3 MultipleAgentV3 Example

In the same way as for the SNMPv3 agent example, AgentV3, you must point the multiple agent application to the security configuration file when you instantiate the multiple agent. This is only the case for the first of the SNMP adaptor servers created by your multiple agent application. All adaptor servers created subsequently by the multiple agent are directed to their corresponding security files in the code of the multiple agent application, when that adaptor server is instantiated.

You must call the MultipleAgentV3 application inside its directory and make sure that the two security configuration files are present in the same directory.

To Run the SNMPv3 MultipleAgentV3 Example
  1. Type the following command:

    $ java -classpath classpath 

    The Java DMK multiple agent is now running on your system.

  2. To manage the agent through a web browser, connect to the following URL: