2.7.3 SNMP MIB Compiler – mibgen

The mibgen tool takes as input a set of SNMP MIBs and generates standard MBeans that you can customize. MIBs can be expressed using either structure of management information (SMI) v1 or SMI v2 syntax.

A MIB is like a management interface. It defines what is exposed, but it does not define how to compute the exposed value. Therefore, MBeans generated by mibgen need to be customized to provide the definitive implementation. The MIB is implemented through Java objects, meaning that it has access to all Java runtime libraries and all features of the dynamic agent where it will be instantiated.

The mibgen compiler parses an SNMP MIB and generates the following:

• An MBean representing the whole MIB

• MBeans representing SNMP groups and table entries

• Classes representing SNMP tables

• Classes representing SNMP enumerated types

• A class mapping symbolic names with object identifiers

The resulting classes should be made accessible in the agent application. When the single MBean representing the whole MIB is registered in the MBean server, all the associated groups are automatically instantiated and registered as well.

The mibgen compiler supports all data structure of SMI v1 and v2 protocols, including:

• Tables with cross-references indexed across several MIBs

• MIBs that contain either SMI v1 or v2 definitions

• Nested groups

• Default value variables

• Row status variables

The Java DMK also provides an example program, showing how an agent can act as an SNMP master agent to access MIBs implemented remotely in subagents. This allows SNMP managers to access hierarchies of agents through a single master agent. In this way, some MIBs can be implemented by native devices and others can be implemented in JMX agents, yet this heterogeneous architecture is completely transparent to the manager issuing a request.