Writing SNMP Manager using SNMP4J

Question

Hello,
I am writing a SNMP Manager that is supposed to do the following:
(1) Send snmp commands to snmp-agents, and handle thier response.
(2) receive snmp traps from snmp-agents.
I am using SNMP4J software package for writing the snmp manager.
I would like to use a SINGLE Snmp object (SNMP4J object) , both
for sending a snmp command and for receiving snmp traps.
SO far, I have written two separate programs:
*** Program 1:
** The first program only listens for Snmp trap-PDUs.
** Its main code is as follows:
     // configure Snmp object
     UdpAddress address = new UdpAddress("127.0.0.1/1990");
     TransportMapping transport = new DefaultUdpTransportMapping(address);
     Snmp snmp = new Snmp(transport);
     transport.listen();
     // handle received traps here
     CommandResponder trapPrinter = new CommandResponder() {
          public synchronized void processPdu(CommandResponderEvent e) {
               PDU command = e.getPdu();
               if (command != null) {
                    System.out.println(command.toString());
     snmp.addCommandResponder(trapPrinter);
*** Program 2:
** The second program sends GET PDUs, and its main code is as follows:
     // configure Snmp object
     UdpAddress targetAddress = new UdpAddress("127.0.0.1/1985");
     CommunityTarget target = new CommunityTarget();
     target.setCommunity(new OctetString("public"));
     target.setAddress(targetAddress);
     target.setRetries(2);
     target.setTimeout(10000); // was 1000 !!!
     target.setVersion(SnmpConstants.version1);
     Snmp snmp = new Snmp(new DefaultUdpTransportMapping());
     snmp.listen();
     // prepare the PDU for sending
     PDU command = new PDU();
     command.setType(PDU.GET);
     command.add(new VariableBinding(new OID("1.3.6.1.4.1.1331.11.5.1.0")));
     // now send the PDU
     ResponseEvent responseEvent = snmp.send(pdu, target);
     if (responseEvent != null)
          // response has arrived. handle it
     else
          System.out.println("null response received...");
I would like to unite these two programs into one, however, I cannot seem to
properly allocate one Snmp object to handle both the sending and receiving of PDUs.
I run two threads: thread-1 that does the listening for snmp traps,
and thread-2 which in charge of sending get/set PDUs.
I allocate the Snmp object in one place as follows:
     TransportMapping transport = new DefaultUdpTransportMapping(new UdpAddress("127.0.0.1/1990"));
     Snmp snmp = new Snmp(transport);
     snmp.listen();
and I transfer it to both threads to be used there.
However, thread-2 sometimes fails to send PDUs using snmp.send(...);
What am I doing wrong?
Can anyone guide me as for how I should allocate the Snmp object so
it is good for both sending PDUs, and for receving traps?
Thanks,
Nefi

Answer 1

Hello,
I am writing a SNMP Manager that is supposed to do the following:
(1) Send snmp commands to snmp-agents, and handle thier response.
(2) receive snmp traps from snmp-agents.
I am using SNMP4J software package for writing the snmp manager.
I would like to use a SINGLE Snmp object (SNMP4J object) , both
for sending a snmp command and for receiving snmp traps.
SO far, I have written two separate programs:
*** Program 1:
** The first program only listens for Snmp trap-PDUs.
** Its main code is as follows:
     // configure Snmp object
     UdpAddress address = new UdpAddress("127.0.0.1/1990");
     TransportMapping transport = new DefaultUdpTransportMapping(address);
     Snmp snmp = new Snmp(transport);
     transport.listen();
     // handle received traps here
     CommandResponder trapPrinter = new CommandResponder() {
          public synchronized void processPdu(CommandResponderEvent e) {
               PDU command = e.getPdu();
               if (command != null) {
                    System.out.println(command.toString());
     snmp.addCommandResponder(trapPrinter);
*** Program 2:
** The second program sends GET PDUs, and its main code is as follows:
     // configure Snmp object
     UdpAddress targetAddress = new UdpAddress("127.0.0.1/1985");
     CommunityTarget target = new CommunityTarget();
     target.setCommunity(new OctetString("public"));
     target.setAddress(targetAddress);
     target.setRetries(2);
     target.setTimeout(10000); // was 1000 !!!
     target.setVersion(SnmpConstants.version1);
     Snmp snmp = new Snmp(new DefaultUdpTransportMapping());
     snmp.listen();
     // prepare the PDU for sending
     PDU command = new PDU();
     command.setType(PDU.GET);
     command.add(new VariableBinding(new OID("1.3.6.1.4.1.1331.11.5.1.0")));
     // now send the PDU
     ResponseEvent responseEvent = snmp.send(pdu, target);
     if (responseEvent != null)
          // response has arrived. handle it
     else
          System.out.println("null response received...");
I would like to unite these two programs into one, however, I cannot seem to
properly allocate one Snmp object to handle both the sending and receiving of PDUs.
I run two threads: thread-1 that does the listening for snmp traps,
and thread-2 which in charge of sending get/set PDUs.
I allocate the Snmp object in one place as follows:
     TransportMapping transport = new DefaultUdpTransportMapping(new UdpAddress("127.0.0.1/1990"));
     Snmp snmp = new Snmp(transport);
     snmp.listen();
and I transfer it to both threads to be used there.
However, thread-2 sometimes fails to send PDUs using snmp.send(...);
What am I doing wrong?
Can anyone guide me as for how I should allocate the Snmp object so
it is good for both sending PDUs, and for receving traps?
Thanks,
Nefi