The Manager Application

The manager application is not affected by proxies in the agents to which it sends requests. It sends the requests to the session of the master agent, in the same way that it would a request for a MIB that is not served by a proxy. In fact, the SNMP manager cannot even distinguish between a MIB served by an agent and another MIB served through a proxy in the agent, except perhaps by analyzing the values returned.

There is one consideration for proxies, and that is the timeout interval. Since the proxy issues another request and potentially answers only at the end of its timeout, the manager must have a longer timeout. The manager should be designed with some knowledge of all sub-agents in a hierarchy, so that the timeout interval can take into account all proxy delays and the multiple communication times.

As with any manager application written with the SNMP manager API, the manager in the proxy example may use the OID table object to refer to the MIB variables by name. Here is the code to initialize the manager:

Example 19-2 Initialization of the SNMP Proxy Manager

String host = argv[0];
String port = argv[1];

// Initialize the SNMP Manager API.
// Specify the OidTables containing all the MIB Demo and MIB II knowledge.
// Use the OidTables generated by mibgen when compiling MIB Demo and MIB II.
//
SnmpOidDatabaseSupport oidDB = new SnmpOidDatabaseSupport();
SnmpOid.setSnmpOidTable(oidDB);
oidDB.add(new RFC1213_MIBOidTable());
oidDB.add(new DEMO_MIBOidTable());
  
SnmpPeer agent = new SnmpPeer(host, Integer.parseInt(port));
SnmpParameters params = new SnmpParameters("public", "private");
SnmpSession session = new SnmpSession("Manager session");
  
// We update the time out to let the agent enough time 
// to do his job before retry.
//
agent.setTimeout(100000);
agent.setSnmpParam(params);
session.setDefaultPeer(agent);

The rest of the manager application is the code for synchronous get and set requests, similar to the one shown in "The Synchronous Manager Example".