/****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one *
* or more contributor license agreements. See the NOTICE file *
* distributed with this work for additional information *
* regarding copyright ownership. The ASF licenses this file *
* to you under the Apache License, Version 2.0 (the *
* "License"); you may not use this file except in compliance *
* with the License. You may obtain a copy of the License at *
* *
* http://www.apache.org/licenses/LICENSE-2.0 *
* *
* Unless required by applicable law or agreed to in writing, *
* software distributed under the License is distributed on an *
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY *
* KIND, either express or implied. See the License for the *
* specific language governing permissions and limitations *
* under the License. *
****************************************************************/
package org.apache.mailet;
import java.util.Collection;
/**
* This interface define the behaviour of the message "routing" inside
* the mailet container. The match(Mail) method returns a Collection of
* recipients that meet this class's criteria.
* <p>
* An important feature of the mailet container is the ability to fork
* processing of messages. When a message first arrives at the server,
* it might have multiple recipients specified. As a message is passed
* to a matcher, the matcher might only "match" one of the listed
* recipients. It would then return only the matching recipient in
* the Collection. The mailet container should then duplicate the
* message splitting the recipient list across the two messages as per
* what the matcher returned.
* <p>
* <b>[THIS PARAGRAPH NOT YET IMPLEMENTED]</b>
* <i>The matcher can extend this forking to further separation by returning
* a Collection of Collection objects. This allows a matcher to fork
* multiple processes if there are multiple recipients that require
* separate processing. For example, we could write a ListservMatcher
* that handles multiple listservs. When someone cross-posts across
* multiple listservs that this matcher handles, it could put each
* listserv address (recipient) that it handles in a separate Collection
* object. By returning each of these Collections within a container
* Collection object, it could indicate to the mailet container how
* many forks to spawn.</i>
* <p>
* This interface defines methods to initialize a matcher, to match
* messages, and to remove a matcher from the server. These are known
* as life-cycle methods and are called in the following sequence:
* <ol>
* <li>The matcher is constructed, then initialized with the init method.</li>
* <li>Any calls from clients to the match method are handled.</li>
* <li>The matcher is taken out of service, then destroyed with the
* destroy method, then garbage collected and finalized.</li>
* </ol>
* In addition to the life-cycle methods, this interface provides the
* getMatcherConfig method, which the matcher can use to get any startup
* information, and the getMatcherInfo method, which allows the matcher
* to return basic information about itself, such as author, version,
* and copyright.
*
* @version 1.0.0, 24/04/1999
*/
public interface Matcher {
/**
* Called by the mailet container to indicate to a matcher that the matcher
* is being taken out of service. This method is only called once all threads
* within the matcher's service method have exited or after a timeout period
* has passed. After the mailet container calls this method, it will not call
* the match method again on this matcher.
* <p>
* This method gives the matcher an opportunity to clean up any resources that
* are being held (for example, memory, file handles, threads) and make sure
* that any persistent state is synchronized with the matcher's current state in memory.
*/
void destroy();
/**
* Returns a MatcherConfig object, which contains initialization and
* startup parameters for this matcher.
* <p>
* Implementations of this interface are responsible for storing the
* MatcherConfig object so that this method can return it. The GenericMatcher
* class, which implements this interface, already does this.
*
* @return the MatcherConfig object that initializes this matcher
*/
MatcherConfig getMatcherConfig();
/**
* Returns information about the matcher, such as author, version, and copyright.
* <p>
* The string that this method returns should be plain text and not markup
* of any kind (such as HTML, XML, etc.).
*
* @return a String containing matcher information
*/
String getMatcherInfo();
/**
* Called by the mailet container to indicate to a matcher that the
* matcher is being placed into service.
* <p>
* The mailet container calls the init method exactly once after instantiating
* the matcher. The init method must complete successfully before the matcher
* can receive any messages.
*
* @param config - a MatcherConfig object containing the matcher's configuration
* and initialization parameters
* @throws javax.mail.MessagingException - if an exception has occurred that
* interferes with the matcher's normal operation
*/
void init( MatcherConfig config ) throws javax.mail.MessagingException;
/**
* Takes a Mail message, looks at any pertinent information, and then returns a subset
* of recipients that meet the "match" conditions.
* <p>
* This method is only called after the matcher's init() method has completed
* successfully.
* <p>
* Matchers typically run inside multithreaded mailet containers that can handle
* multiple requests concurrently. Developers must be aware to synchronize access
* to any shared resources such as files, network connections, and as well as the
* matcher's class and instance variables. More information on multithreaded
* programming in Java is available in <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">the
* Java tutorial on multi-threaded programming</a>.
*
* @param mail - the Mail object that contains the message and routing information
* @return a Collection of String objects (recipients) that meet the match criteria
* @throws MessagingException - if an message or address parsing exception occurs or
* an exception that interferes with the matcher's normal operation
*/
Collection match( Mail mail ) throws javax.mail.MessagingException;
}
|
