/* * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ 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. * * <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 <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 <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;}