[SNMP4J] The method snmp.send() returns a null ResponseEvent, why?

[Frank Fock]

Hi,

A TRAP PDU is not confirmed, so there will be
never a response and therefore the response is
null and everything is fine as it should be.

Best regards,
Frank

xsong at profilium.com wrote:
> Hi, 
> 
> I just started to write code for SNMP, I found SNMP4j is very help. The following code trys to send out a TRAP pdu, but it does not work. Debug finds that everythings is find until the snmp.send() is called, the method is supposed to returns a ResponseEvent, but it returns null.
> 
> .............
> // set up a default SNMP session for UDP and with SNMPv3 support
> TransportMapping udpTransport = new DefaultUdpTransportMapping();
> Snmp snmp = new Snmp(udpTransport);
> USM usm = new USM(SecurityProtocols.getInstance(),
>                  new OctetString(MPv3.createLocalEngineID()), 0);
> SecurityModels.getInstance().addSecurityModel(usm);
> 			
> // set up the target
> Address targetAddress = GenericAddress.parse("udp:192.168.1.156/162");
> CommunityTarget target = new CommunityTarget();
> target.setCommunity(new OctetString("public"));
> target.setAddress(targetAddress);
> target.setRetries(2);
> target.setTimeout(1500);
> target.setVersion(SnmpConstants.version2c);
> 			
> // create a SNMP trap PDU
> PDU trapPdu = new PDU();
> trapPdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.1"),
> 	    new OctetString("Alarm 1"))); 
> trapPdu.add(new VariableBinding(new OID("1.3.6.1.2.1.2.1"),
>             new OctetString("Alarm 2"))); 
> trapPdu.setType(PDU.TRAP);
> 
> // sending out the SNMP trap PDU synchronously
> ResponseEvent response = snmp.send(trapPdu, target);
> if (response.getResponse() == null) {
>     System.out.println("sending request timed out");
> }
> else {
>     System.out.println("Received response from "
>                         +response.getPeerAddress());
>     // dump response PDU
>     System.out.println(response.getResponse().toString());
> };
> ...............
> 
> I traced the inside steps of the snmp.send(), it seems everything is fine there: the pdu message is encoded, written to the buffer, and sent out a socket. Could anyone tell me what is wrong with my code? 
> 
> Thanks...
> 
> Xinxin
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