public interface

SnmpUserDataFactory

com.sun.jmx.snmp.agent.SnmpUserDataFactory
Known Indirect Subclasses

Class Overview

This interface is provided to enable fine customization of the SNMP agent behaviour.

You will not need to implement this interface except if your agent needs extra customization requiring some contextual information.

If an SnmpUserDataFactory is set on the SnmpAdaptorServer, then a new object containing user-data will be allocated through this factory for each incoming request. This object will be passed along to the SnmpMibAgent within SnmpMibRequest objects. By default, no SnmpUserDataFactory is set on the SnmpAdaptorServer, and the contextual object passed to SnmpMibAgent is null.

You can use this feature to obtain on contextual information (such as community string etc...) or to implement a caching mechanism, or for whatever purpose might be required by your specific agent implementation.

The sequence allocateUserData() / releaseUserData() can also be used to implement a caching mechanism:

  • allocateUserData() could be used to allocate some cache space,
  • and releaseUserData() could be used to flush it.

This API is a Sun Microsystems internal API and is subject to change without notice.

See Also

Summary

Public Methods
abstract Object allocateUserData(SnmpPdu requestPdu)
Called by the SnmpAdaptorServer adaptor.
abstract void releaseUserData(Object userData, SnmpPdu responsePdu)
Called by the SnmpAdaptorServer adaptor.

Public Methods

public abstract Object allocateUserData (SnmpPdu requestPdu)

Called by the SnmpAdaptorServer adaptor. Allocate a contextual object containing some user data. This method is called once for each incoming SNMP request. The scope of this object will be the whole request. Since the request can be handled in several threads, the user should make sure that this object can be accessed in a thread-safe manner. The SNMP framework will never access this object directly - it will simply pass it to the SnmpMibAgent within SnmpMibRequest objects - from where it can be retrieved through the getUserData() accessor. null is considered to be a valid return value. This method is called just after the SnmpPduPacket has been decoded.

Parameters
requestPdu The SnmpPduPacket received from the SNMP manager. This parameter is owned by the SNMP framework and must be considered as transient. If you wish to keep some of its content after this method returns (by storing it in the returned object for instance) you should clone that information.
Returns
  • A newly allocated user-data contextual object, or null
Throws
SnmpStatusException If an SnmpStatusException is thrown, the request will be aborted.

public abstract void releaseUserData (Object userData, SnmpPdu responsePdu)

Called by the SnmpAdaptorServer adaptor. Release a previously allocated contextual object containing user-data. This method is called just before the responsePdu is sent back to the manager. It gives the user a chance to alter the responsePdu packet before it is encoded, and to free any resources that might have been allocated when creating the contextual object.

Parameters
userData The contextual object being released.
responsePdu The SnmpPduPacket that will be sent back to the SNMP manager. This parameter is owned by the SNMP framework and must be considered as transient. If you wish to keep some of its content after this method returns you should clone that information.
Throws
SnmpStatusException If an SnmpStatusException is thrown, the responsePdu is dropped and nothing is returned to to the manager.