Synchronous Managers Accessing Several Agents
The SNMP API enables you to configure a synchronous SNMPv3 manager that can access several agents. The SyncManagerMultiV3 example demonstrates a simple SNMPv3 manager API that makes requests on two SNMPv3 agents. For the sake of simplicity, this manager does not listen for traps.
Example 19–5 SNMPv3 SyncManagerMultiV3 Example
//Check host and port arguments
//
final String host1 = argv[0];
final String port1 = argv[1];
final String host2 = argv[2];
final String port2 = argv[3];
// Initialize the trace property.
[...]
// Initialize the SNMP Manager API.
//
final SnmpOidTableSupport oidTable = new RFC1213_MIBOidTable();
SnmpOid.setSnmpOidTable(oidTable);
[...]
// Build the session.
//
try {
// When instantiating a session, a new SNMP V3 engine is
// instantiated.
//
session= new SnmpSession("SyncManagerMultiV3 session");
}catch(SnmpStatusException e) {
println(e.getMessage());
java.lang.System.exit(0);
}
catch(IllegalArgumentException e) {
// If the engine configuration is faulty
//
println(e.getMessage());
java.lang.System.exit(0);
}
// Get the SnmpEngine.
//
final SnmpEngine engine = session.getEngine();
// Create a SnmpPeer object for representing the first
// entity to communicate with.
//
final SnmpUsmPeer agent1 =
new SnmpUsmPeer(engine, host1, Integer.parseInt(port1));
//Create the second peer.
//
final SnmpUsmPeer agent2 =
new SnmpUsmPeer(engine, host2, Integer.parseInt(port2));
// Create parameters to associate to the entity to
// communicate with.
//
final SnmpUsmParameters p =
new SnmpUsmParameters(engine, "defaultUser");
// Set security level to authNoPriv.
//
p.setSecurityLevel(SnmpDefinitions.authNoPriv);
// Contextualize the send request
//
p.setContextName("TEST-CONTEXT".getBytes());
// Specify a contextEngineId
//
p.setContextEngineId(agent1.getEngineId().getBytes());
// Associate the newly created parameter to the agent
//
agent1.setParams(p);
// Discover timeliness and boot
agent1.processUsmTimelinessDiscovery();
// Build the list of variables you want to query
//
final SnmpVarBindList list =
new SnmpVarBindList("SyncManagerMultiV3 varbind list");
// Read the "sysDescr" variable
//
list.addVarBind("sysDescr.0");
// Make the SNMP get request on the first agent agent1
// and wait for the result
//
SnmpRequest request =
session.snmpGetRequest(agent1, null, list);
println("SyncManagerMultiV3::main:" +
" Send get request to SNMP agent on " +
host1 + " at port " + port1);
boolean completed = request.waitForCompletion(10000);
// Check for a timeout
//
if (completed == false) {
println("SyncManagerMultiV3::main:" +
" Request timed out. Check if agent can
be reached");
// Print request
//
println("Request: " + request.toString());
java.lang.System.exit(0);
}
// Check if the response contains an error
//
int errorStatus = request.getErrorStatus();
if (errorStatus != SnmpDefinitions.snmpRspNoError) {
println("Error status = " +
SnmpRequest.snmpErrorToString(errorStatus));
println("Error index = " +
request.getErrorIndex());
java.lang.System.exit(0);
}
// Display the content of the result
//
SnmpVarBindList result = request.getResponseVarBindList();
println("Result: \n" + result);
println("\n>> Press Enter if you want to send the request" +
" on the second agent.\n");
java.lang.System.in.read();
// Repeat the process for the second agent agent2.
//
SnmpUsmParameters p2 =
new SnmpUsmParameters(engine, "defaultUser");
p2.setSecurityLevel(SnmpDefinitions.authNoPriv);
p2.setContextName("TEST-CONTEXT".getBytes());
p2.setContextEngineId(agent2.getEngineId().getBytes());
// Associate the updated parameters with agent2.
//
agent2.setParams(p2);
// Discover timeliness and boot
//
agent2.processUsmTimelinessDiscovery();
// Make the request with agent2
//
request = session.snmpGetRequest(agent2, null, list);
println("SyncManagerMultiV3::main:" +
" Send get request to SNMP agent on " +
host2 + " at port " + port2);
completed = request.waitForCompletion(10000);
// Check for a timeout
//
if (completed == false) {
println("SyncManagerMultiV3::main:" +
" Request timed out. Check if agent can be
reached");
// Print request.
//
println("Request: " + request.toString());
java.lang.System.exit(0);
}
// Check if the response contains an error
//
errorStatus = request.getErrorStatus();
if (errorStatus != SnmpDefinitions.snmpRspNoError) {
println("Error status = " +
SnmpRequest.snmpErrorToString(errorStatus));
println("Error index = " +
request.getErrorIndex());
java.lang.System.exit(0);
}
// Display the content of the result
//
result = request.getResponseVarBindList();
println("Result: \n" + result);
println("\n>> Press Enter if you want to stop " +
"this manager.\n");
java.lang.System.in.read();
// End the session
//
session.destroySession();
}
|
The SyncManagerMultiV3 example essentially performs the same actions as the SyncManagerV3 example, except it creates two SNMP USM peers rather than just one. The two peer agents are each created in exactly the same way as in the single peer example.
Both the peer agents are accessed using a common set of parameters, which are kept in the jdmk.security file for the session. This jdmk.security file contains two rows, one for each SNMP USM peer agent, as shown in the following example.
Example 19–6 jdmk.security File for the SyncManagerMultiV3 Example
#Authentication only. userEntry=0x8000002a05819dcb6e00001f95,defaultUser,,usmHMACMD5AuthProtocol, mypasswd userEntry=0x8000002a05819dcb6e00001f96,defaultUser,,usmHMACMD5AuthProtocol, mypasswd # #####APPENDED PROPERTY#### localEngineBoots=5 # #####APPENDED PROPERTY#### localEngineID=0x8000002a05000000ec4c49ded9 |
If you configure your manager to create a greater number of peers, then its associated jdmk.security file must contain a corresponding number of entries, one for each authoritative engine with which the manager will communicate.
In this example, the only difference between the two userEntry rows is between the engine ID numbers. These engine IDs correspond to the engines of the two SNMP adaptor servers created by the MultipleAgentV3 example in Multiple Agents.
To Run the SyncManagerMultiV3 Example
-
Before running the example, you must have run mibgen and compiled the Java classes in the examplesDir/Snmp/Manager directory.
See To Run the SyncManager Example for instructions if you have not already done this.
-
Make sure that no other agent is running, and start the multiple SNMPv3 agent, MultipleAgentV3, in examplesDir/Snmp/Agent.
See Running the SNMPv3 MultipleAgentV3 Example if you have not already built and run this example.
Type the following commands to start the MultipleAgentV3 example:
$ cd examplesDir/Snmp/Agent $ java -classpath classpath -Djdmk.security.file=./jdmk.security MultipleAgentV3
The MultipleAgentV3 example simulates two SNMPv3 agents in one process. We shall make these agents peers of SyncManagerMultiV3.
Be sure to run the multiple agent in its directory, otherwise it cannot find its jdmk.security and jdmk2.security files.
-
Start the manager application in another window to connect to these two agents.
If you want to run the manager on a different host from the one where the agents are running, replace localhost with the name of the host where you started the agents. Both the agents in the MultipleAgentV3 example run on the same host.
$ cd examplesDir/Snmp/Manager $ java -classpath classpath -Djdmk.security.file=./jdmk.security SyncManagerMultiV3 localhost 8085 localhost 8087
Be sure to run the manager in its directory, otherwise it cannot find its jdmk.security file.
-
You should see sending a request to the first agent. Press Enter to send a request to the second agent.
You will now see the manager sending a second request to the agent on port 8087.
-
Press Enter to stop the manager
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