Java Dynamic Management Kit 5.0 Tutorial

Synchronous SNMPv1 and SNMPv2 Managers

Example 19–1 shows the code of the main method of the SyncManager application for SNMPv1 and SNMPv2. It applies all the steps described in the previous section to execute a very simple management operation.

Example 19–1 SNMPv1 and SNMPv2 SyncManager Example

The SyncManager example is found in the examplesDir/Snmp/Manager directory.

// read the command line parameters
String host = argv[0];
String port = argv[1];

// Specify the OidTable containing all the MIB II knowledge
// Use the OidTable generated by mibgen when compiling MIB II
SnmpOidTableSupport oidTable = new RFC1213_MIBOidTable();
SnmpPeer agent = new SnmpPeer(host, Integer.parseInt(port));
// When creating the parameter object, you can specify the
// read and write community to be used when querying the agent.
SnmpParameters params = new SnmpParameters("public", "private");

SnmpSession session = new SnmpSession("SyncManager session");

// When invoking a service provided by the SnmpSession, it
// will use the default peer if none is specified explicitly

// Create a listener and dispatcher for SNMP traps:
// SnmpEventReportDispatcher will run as a thread and
// listens for traps in UDP port = agent port + 1
SnmpEventReportDispatcher trapAgent =
    new SnmpEventReportDispatcher(Integer.parseInt(port)+1);
// TrapListenerImpl will receive a callback
// when a valid trap PDU is received.
trapAgent.addTrapListener(new TrapListenerImpl()); 
new Thread(trapAgent).start();

// Build the list of variables you want to query.
// For debugging, you can associate a name to your list.
SnmpVarbindList list= new SnmpVarbindList(
    "SyncManager varbind list");
// We want to read the "sysDescr" variable.
// Make the SNMP get request and wait for the result.
SnmpRequest request = session.snmpGet(null, list);
boolean completed = request.waitForCompletion(10000);

// Check for a timeout of the request.
if (completed == false) {
"Request timed out. Check if agent can be reached");

// Check if the response contains an error.
int errorStatus = request.getErrorStatus();
if (errorStatus != SnmpDefinitions.snmpRspNoError) {
    java.lang.System.out.println("Error status = " + 
    java.lang.System.out.println("Error index = " +

// Now we can extract the content of the result.
SnmpVarbindList result = request.getResponseVbList();
java.lang.System.out.println("Result: \n" + result);

[...] // Wait for user to type enter. Traps will be handled.

// End the session properly and we're done

In this SNMP manager application, we demonstrate how to implement and enable a trap listener for the traps sent by the agent. First we need to instantiate an SnmpEventReportDispatcher object. Then we add our listener implementation through its addTrapListener method, and finally we start its thread. Trap listeners can be implemented in any manager using the SNMP manager API, not only synchronous managers.