1 /************************************************************************
2 * Copyright (c) 1999-2006 The Apache Software Foundation. *
3 * All rights reserved. *
4 * ------------------------------------------------------------------- *
5 * Licensed under the Apache License, Version 2.0 (the "License"); you *
6 * may not use this file except in compliance with the License. You *
7 * may obtain a copy of the License at: *
8 * *
9 * http://www.apache.org/licenses/LICENSE-2.0 *
10 * *
11 * Unless required by applicable law or agreed to in writing, software *
12 * distributed under the License is distributed on an "AS IS" BASIS, *
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or *
14 * implied. See the License for the specific language governing *
15 * permissions and limitations under the License. *
16 ***********************************************************************/
17
18 package org.apache.mailet;
19
20 /***
21 * Draft of a Mailet inteface. The <code>service</code> perform all needed work
22 * on the Mail object. Whatever remains at the end of the service is considered
23 * to need futher processing and will go to the next Mailet if there is one
24 * configured or will go to the error processor if not.
25 * Setting a Mail state (setState(String)) to Mail.GHOST or cleaning its recipient
26 * list has the same meaning that s no more processing is needed.
27 * Instead of creating new messages, the mailet can put a message with new recipients
28 * at the top of the mail queue, or insert them immediately after it's execution
29 * through the API are provided by the MailetContext interface.
30 * <p>
31 * This interface defines methods to initialize a mailet, to service messages, and to
32 * remove a mailet from the server. These are known as life-cycle methods and are called
33 * in the following sequence:
34 * <ol>
35 * <li>The mailet is constructed, then initialized with the init method. </li>
36 * <li>Any messages for the service method are handled.</li>
37 * <li>The mailet is taken out of service, then destroyed with the destroy method,
38 * then garbage collected and finalized.</li>
39 * </ol>
40 * In addition to the life-cycle methods, this interface provides the getMailetConfig
41 * method, which the mailet can use to get any startup information, and the
42 * getMailetInfo method, which allows the mailet to return basic information about itself,
43 * such as author, version, and copyright.
44 *
45 * @version 1.0.0, 24/04/1999
46 */
47 public interface Mailet {
48
49 /***
50 * Called by the mailet container to indicate to a mailet that the
51 * mailet is being taken out of service. This method is only called once
52 * all threads within the mailet's service method have exited or after a
53 * timeout period has passed. After the mailet container calls this method,
54 * it will not call the service method again on this mailet.
55 * <p>
56 * This method gives the mailet an opportunity to clean up any resources that
57 * are being held (for example, memory, file handles, threads) and make sure
58 * that any persistent state is synchronized with the mailet's current state in memory.
59 */
60 void destroy();
61
62 /***
63 * Returns information about the mailet, such as author, version, and
64 * copyright.
65 * <p>
66 * The string that this method returns should be plain text and not markup
67 * of any kind (such as HTML, XML, etc.).
68 *
69 * @return a String containing servlet information
70 */
71 String getMailetInfo();
72
73 /***
74 * Returns a MailetConfig object, which contains initialization and
75 * startup parameters for this mailet.
76 * <p>
77 * Implementations of this interface are responsible for storing the MailetConfig
78 * object so that this method can return it. The GenericMailet class, which implements
79 * this interface, already does this.
80 *
81 * @return the MailetConfig object that initializes this mailet
82 */
83 MailetConfig getMailetConfig();
84
85 /***
86 * Called by the mailet container to indicate to a mailet that the
87 * mailet is being placed into service.
88 * <p>
89 * The mailet container calls the init method exactly once after
90 * instantiating the mailet. The init method must complete successfully
91 * before the mailet can receive any requests.
92 *
93 * @param config - a MailetConfig object containing the mailet's configuration
94 * and initialization parameters
95 * @throws javax.mail.MessagingException - if an exception has occurred that interferes with
96 * the mailet's normal operation
97 */
98 void init(MailetConfig config) throws javax.mail.MessagingException;
99
100 /***
101 * Called by the mailet container to allow the mailet to process to
102 * a message.
103 * <p>
104 * This method is only called after the mailet's init() method has completed
105 * successfully.
106 * <p>
107 * Mailets typically run inside multithreaded mailet containers that can handle
108 * multiple requests concurrently. Developers must be aware to synchronize access
109 * to any shared resources such as files, network connections, as well as the
110 * mailet's class and instance variables. More information on multithreaded
111 * programming in Java is available in <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">the
112 * Java tutorial on multi-threaded programming</a>.
113 *
114 * @param mail - the Mail object that contains the message and routing information
115 * @throws javax.mail.MessagingException - if a message or address parsing exception occurs or
116 * an exception that interferes with the mailet's normal operation
117 */
118 void service(Mail mail) throws javax.mail.MessagingException;
119 }