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package com.sun.jmx.snmp.agent;

import com.sun.jmx.snmp.SnmpPduPacket;
import com.sun.jmx.snmp.SnmpPdu;
import com.sun.jmx.snmp.SnmpStatusException;


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:
/**
 * This interface is provided to enable fine customization of the SNMP
 * agent behaviour.
 *
 * <p>You will not need to implement this interface except if your agent
 * needs extra customization requiring some contextual information.</p>
 *
 * <p>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.</p>
 *
 * <p>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.</p>
 *
 * <p>The sequence <code>allocateUserData() / releaseUserData()</code> can
 * also be used to implement a caching mechanism:
 * <ul>
 * <li><code>allocateUserData()</code> could be used to allocate
 *         some cache space,</li>
 * <li>and <code>releaseUserData()</code> could be used to flush it.</li>
 * </ul></p>
 *
 * <p><b>This API is a Sun Microsystems internal API  and is subject
 * to change without notice.</b></p>
 * @see com.sun.jmx.snmp.agent.SnmpMibRequest
 * @see com.sun.jmx.snmp.agent.SnmpMibAgent
 * @see com.sun.jmx.snmp.daemon.SnmpAdaptorServer
 *
 **/
public interface SnmpUserDataFactory {
    
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.

Params:
  • 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.
Throws:
Returns:A newly allocated user-data contextual object, or
        null
Since:1.5
/**
     * Called by the <CODE>SnmpAdaptorServer</CODE> 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 <code>SnmpMibAgent</code> within
     * <code>SnmpMibRequest</code> objects - from where it can be retrieved
     * through the {@link com.sun.jmx.snmp.agent.SnmpMibRequest#getUserData() getUserData()} accessor.
     * <code>null</code> is considered to be a valid return value.
     *
     * This method is called just after the SnmpPduPacket has been
     * decoded.
     *
     * @param requestPdu The SnmpPduPacket received from the SNMP manager.
     *        <b>This parameter is owned by the SNMP framework and must be
     *        considered as transient.</b> 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.
     *
     * @return A newly allocated user-data contextual object, or
     *         <code>null</code>
     * @exception SnmpStatusException If an SnmpStatusException is thrown,
     *            the request will be aborted.
     *
     * @since 1.5
     **/
    public Object allocateUserData(SnmpPdu requestPdu)
        throws SnmpStatusException;

    
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.

Params:
  • 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.
Since:1.5
/**
     * Called by the <CODE>SnmpAdaptorServer</CODE> 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.
     *
     * @param userData The contextual object being released.
     * @param responsePdu The SnmpPduPacket that will be sent back to the
     *        SNMP manager.
     *        <b>This parameter is owned by the SNMP framework and must be
     *        considered as transient.</b> If you wish to keep some of its
     *        content after this method returns you should clone that
     *        information.
     *
     * @exception SnmpStatusException If an SnmpStatusException is thrown,
     *            the responsePdu is dropped and nothing is returned to
     *            to the manager.
     *
     * @since 1.5
     **/
    public void releaseUserData(Object userData, SnmpPdu responsePdu)
        throws SnmpStatusException;
}