1 /*****************************************************************
2 * Licensed to the Apache Software Foundation (ASF) under one *
3 * or more contributor license agreements. See the NOTICE file *
4 * distributed with this work for additional information *
5 * regarding copyright ownership. The ASF licenses this file *
6 * to you under the Apache License, Version 2.0 (the *
7 * "License"); you may not use this file except in compliance *
8 * with the License. You may obtain a copy of the License at *
9 * *
10 * http://www.apache.org/licenses/LICENSE-2.0 *
11 * *
12 * Unless required by applicable law or agreed to in writing, *
13 * software distributed under the License is distributed on an *
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY *
15 * KIND, either express or implied. See the License for the *
16 * specific language governing permissions and limitations *
17 * under the License. *
18 ****************************************************************/
19
20 package org.apache.mailet;
21
22 /***
23 * Draft of a Mailet inteface. The <code>service</code> perform all needed work
24 * on the Mail object. Whatever remains at the end of the service is considered
25 * to need futher processing and will go to the next Mailet if there is one
26 * configured or will go to the error processor if not.
27 * Setting a Mail state (setState(String)) to Mail.GHOST or cleaning its recipient
28 * list has the same meaning that s no more processing is needed.
29 * Instead of creating new messages, the mailet can put a message with new recipients
30 * at the top of the mail queue, or insert them immediately after it's execution
31 * through the API are provided by the MailetContext interface.
32 * <p>
33 * This interface defines methods to initialize a mailet, to service messages, and to
34 * remove a mailet from the server. These are known as life-cycle methods and are called
35 * in the following sequence:
36 * <ol>
37 * <li>The mailet is constructed, then initialized with the init method. </li>
38 * <li>Any messages for the service method are handled.</li>
39 * <li>The mailet is taken out of service, then destroyed with the destroy method,
40 * then garbage collected and finalized.</li>
41 * </ol>
42 * In addition to the life-cycle methods, this interface provides the getMailetConfig
43 * method, which the mailet can use to get any startup information, and the
44 * getMailetInfo method, which allows the mailet to return basic information about itself,
45 * such as author, version, and copyright.
46 *
47 * @version 1.0.0, 24/04/1999
48 */
49 public interface Mailet {
50
51 /***
52 * Called by the mailet container to indicate to a mailet that the
53 * mailet is being taken out of service. This method is only called once
54 * all threads within the mailet's service method have exited or after a
55 * timeout period has passed. After the mailet container calls this method,
56 * it will not call the service method again on this mailet.
57 * <p>
58 * This method gives the mailet an opportunity to clean up any resources that
59 * are being held (for example, memory, file handles, threads) and make sure
60 * that any persistent state is synchronized with the mailet's current state in memory.
61 */
62 void destroy();
63
64 /***
65 * Returns information about the mailet, such as author, version, and
66 * copyright.
67 * <p>
68 * The string that this method returns should be plain text and not markup
69 * of any kind (such as HTML, XML, etc.).
70 *
71 * @return a String containing servlet information
72 */
73 String getMailetInfo();
74
75 /***
76 * Returns a MailetConfig object, which contains initialization and
77 * startup parameters for this mailet.
78 * <p>
79 * Implementations of this interface are responsible for storing the MailetConfig
80 * object so that this method can return it. The GenericMailet class, which implements
81 * this interface, already does this.
82 *
83 * @return the MailetConfig object that initializes this mailet
84 */
85 MailetConfig getMailetConfig();
86
87 /***
88 * Called by the mailet container to indicate to a mailet that the
89 * mailet is being placed into service.
90 * <p>
91 * The mailet container calls the init method exactly once after
92 * instantiating the mailet. The init method must complete successfully
93 * before the mailet can receive any requests.
94 *
95 * @param config - a MailetConfig object containing the mailet's configuration
96 * and initialization parameters
97 * @throws javax.mail.MessagingException - if an exception has occurred that interferes with
98 * the mailet's normal operation
99 */
100 void init(MailetConfig config) throws javax.mail.MessagingException;
101
102 /***
103 * Called by the mailet container to allow the mailet to process to
104 * a message.
105 * <p>
106 * This method is only called after the mailet's init() method has completed
107 * successfully.
108 * <p>
109 * Mailets typically run inside multithreaded mailet containers that can handle
110 * multiple requests concurrently. Developers must be aware to synchronize access
111 * to any shared resources such as files, network connections, as well as the
112 * mailet's class and instance variables. More information on multithreaded
113 * programming in Java is available in <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">the
114 * Java tutorial on multi-threaded programming</a>.
115 *
116 * @param mail - the Mail object that contains the message and routing information
117 * @throws javax.mail.MessagingException - if a message or address parsing exception occurs or
118 * an exception that interferes with the mailet's normal operation
119 */
120 void service(Mail mail) throws javax.mail.MessagingException;
121 }