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Java > Open Source Codes > org > mr > api > jms > selector > SelectorManager


1 /*
2  * Copyright 2002 by
3  * <a HREF="http://www.coridan.com">Coridan</a>
4  * <a HREF="mailto: support@coridan.com ">support@coridan.com</a>
5  *
6  * The contents of this file are subject to the Mozilla Public License Version
7  * 1.1 (the "License"); you may not use this file except in compliance with the
8  * License. You may obtain a copy of the License at
9  * http://www.mozilla.org/MPL/
10  *
11  * Software distributed under the License is distributed on an "AS IS" basis,
12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13  * for the specific language governing rights and limitations under the
14  * License.
15  *
16  * The Original Code is "MantaRay" (TM).
17  *
18  * The Initial Developer of the Original Code is Yuval Lubowich.
19  * Portions created by the Initial Developer are Copyright (C) 2006
20  * Coridan Inc. All Rights Reserved.
21  *
22  * Contributor(s): all the names of the contributors are added in the source
23  * code where applicable.
24  *
25  * Alternatively, the contents of this file may be used under the terms of the
26  * LGPL license (the "GNU LESSER GENERAL PUBLIC LICENSE"), in which case the
27  * provisions of LGPL are applicable instead of those above. If you wish to
28  * allow use of your version of this file only under the terms of the LGPL
29  * License and not to allow others to use your version of this file under
30  * the MPL, indicate your decision by deleting the provisions above and
31  * replace them with the notice and other provisions required by the LGPL.
32  * If you do not delete the provisions above, a recipient may use your version
33  * of this file under either the MPL or the GNU LESSER GENERAL PUBLIC LICENSE.
34  
35  *
36  * This library is free software; you can redistribute it and/or modify it
37  * under the terms of the MPL as stated above or under the terms of the GNU
38  * Lesser General Public License as published by the Free Software Foundation;
39  * either version 2.1 of the License, or any later version.
40  *
41  * This library is distributed in the hope that it will be useful, but WITHOUT
42  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
43  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
44  * License for more details.
45  */
46 package org.mr.api.jms.selector;
47
48 import java.util.HashMap JavaDoc;
49 import java.util.Map JavaDoc;
50
51 import javax.jms.InvalidSelectorException JavaDoc;
52 import javax.jms.Message JavaDoc;
53
54 import org.mr.api.jms.selector.syntax.Selector;
55 import org.mr.kernel.services.PayLoadSelector;
56 import org.mr.core.protocol.MantaBusMessage;
57
58 import org.apache.commons.logging.Log;
59 import org.apache.commons.logging.LogFactory;
60 /**
61  * This class represents a selector manager,
62  * the selector manager is called by the agent whenever a message
63  * selector is used by a consumer. The manager checks to see if the message selector
64  * exists and in case it does, the appropreate selector is run.
65  *
66  * @version 1.0
67  * @since Feb 3, 2004
68  * @author Yuval Lubowich
69  *
70  */
71 public class SelectorManager implements PayLoadSelector{
72     
73     private Map JavaDoc selectorMap = null;
74     private static SelectorManager instance = null;
75     private Log log;
76     
77     
78     private SelectorManager(){
79         selectorMap = new HashMap JavaDoc(11);
80         log=LogFactory.getLog("SelectorManager");
81     }//SelectorManager
82
83     
84     public static synchronized SelectorManager getInstance(){
85         if (instance == null)
86             instance = new SelectorManager();
87         
88         return instance;
89     }//getInstance
90
91     
92     public boolean accept(String JavaDoc statement , MantaBusMessage msg){
93         
94         boolean result = true;
95         
96         Selector selector = (Selector)selectorMap.get(statement);
97         if (selector == null){
98             try {
99                 //Create a new selector and place it in the SelectorMap.
100 selector = new Selector(statement);
101                 selectorMap.put(statement,selector);
102             }//try
103 catch (InvalidSelectorException JavaDoc e) {
104                 // Ignor this as the statement was validated before on the initiating agent.
105 // This exception should not happen at all.
106 if(log.isErrorEnabled())
107                     log.error("InvalidSelectorException, statement " + statement + " is invalid.",e);
108             }//catch
109 }//if
110
111         Message JavaDoc message = (Message JavaDoc)msg.getPayload();
112         if (message != null)
113             result = selector.accept(message);
114         
115         return result;
116     }//accept
117 }//SelectorManager
118
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