1 /*
2 * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package com.sun.jmx.snmp.agent;
27
28 import com.sun.jmx.snmp.SnmpPduPacket;
29 import com.sun.jmx.snmp.SnmpPdu;
30 import com.sun.jmx.snmp.SnmpStatusException;
31
32 /**
33 * This interface is provided to enable fine customization of the SNMP
34 * agent behaviour.
35 *
36 * <p>You will not need to implement this interface except if your agent
37 * needs extra customization requiring some contextual information.</p>
38 *
39 * <p>If an SnmpUserDataFactory is set on the SnmpAdaptorServer, then a new
40 * object containing user-data will be allocated through this factory
41 * for each incoming request. This object will be passed along to
42 * the SnmpMibAgent within SnmpMibRequest objects. By default, no
43 * SnmpUserDataFactory is set on the SnmpAdaptorServer, and the contextual
44 * object passed to SnmpMibAgent is null.</p>
45 *
46 * <p>You can use this feature to obtain on contextual information
47 * (such as community string etc...) or to implement a caching
48 * mechanism, or for whatever purpose might be required by your specific
49 * agent implementation.</p>
50 *
51 * <p>The sequence <code>allocateUserData() / releaseUserData()</code> can
52 * also be used to implement a caching mechanism:
53 * <ul>
54 * <li><code>allocateUserData()</code> could be used to allocate
55 * some cache space,</li>
56 * <li>and <code>releaseUserData()</code> could be used to flush it.</li>
57 * </ul></p>
58 *
59 * <p><b>This API is a Sun Microsystems internal API and is subject
60 * to change without notice.</b></p>
61 * @see com.sun.jmx.snmp.agent.SnmpMibRequest
62 * @see com.sun.jmx.snmp.agent.SnmpMibAgent
63 * @see com.sun.jmx.snmp.daemon.SnmpAdaptorServer
64 *
65 **/
66 public interface SnmpUserDataFactory {
67 /**
68 * Called by the <CODE>SnmpAdaptorServer</CODE> adaptor.
69 * Allocate a contextual object containing some user data. This method
70 * is called once for each incoming SNMP request. The scope
71 * of this object will be the whole request. Since the request can be
72 * handled in several threads, the user should make sure that this
73 * object can be accessed in a thread-safe manner. The SNMP framework
74 * will never access this object directly - it will simply pass
75 * it to the <code>SnmpMibAgent</code> within
76 * <code>SnmpMibRequest</code> objects - from where it can be retrieved
77 * through the {@link com.sun.jmx.snmp.agent.SnmpMibRequest#getUserData() getUserData()} accessor.
78 * <code>null</code> is considered to be a valid return value.
79 *
80 * This method is called just after the SnmpPduPacket has been
81 * decoded.
82 *
83 * @param requestPdu The SnmpPduPacket received from the SNMP manager.
84 * <b>This parameter is owned by the SNMP framework and must be
85 * considered as transient.</b> If you wish to keep some of its
86 * content after this method returns (by storing it in the
87 * returned object for instance) you should clone that
88 * information.
89 *
90 * @return A newly allocated user-data contextual object, or
91 * <code>null</code>
92 * @exception SnmpStatusException If an SnmpStatusException is thrown,
93 * the request will be aborted.
94 *
95 * @since 1.5
96 **/
97 public Object allocateUserData(SnmpPdu requestPdu)
98 throws SnmpStatusException;
99
100 /**
101 * Called by the <CODE>SnmpAdaptorServer</CODE> adaptor.
102 * Release a previously allocated contextual object containing user-data.
103 * This method is called just before the responsePdu is sent back to the
104 * manager. It gives the user a chance to alter the responsePdu packet
105 * before it is encoded, and to free any resources that might have
106 * been allocated when creating the contextual object.
107 *
108 * @param userData The contextual object being released.
109 * @param responsePdu The SnmpPduPacket that will be sent back to the
110 * SNMP manager.
111 * <b>This parameter is owned by the SNMP framework and must be
112 * considered as transient.</b> If you wish to keep some of its
113 * content after this method returns you should clone that
114 * information.
115 *
116 * @exception SnmpStatusException If an SnmpStatusException is thrown,
117 * the responsePdu is dropped and nothing is returned to
118 * to the manager.
119 *
120 * @since 1.5
121 **/
122 public void releaseUserData(Object userData, SnmpPdu responsePdu)
123 throws SnmpStatusException;
124 }