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Java > Open Source Codes > org > objectweb > dream > Pull


1 /**
2  * Dream
3  * Copyright (C) 2003-2004 INRIA Rhone-Alpes
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2 of the License, or (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this library; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  *
19  * Contact : dream@objectweb.org
20  *
21  * Initial developer(s): Matthieu Leclercq
22  * Contributor(s): Vivien Quema
23  */
24
25 package org.objectweb.dream;
26
27 import java.util.Map JavaDoc;
28
29 import org.objectweb.dream.message.Message;
30
31 /**
32  * Common <I>Pull </I> interface for Dream components. This interface defines a
33  * method <code>pull</code> that allows a component to ask another component
34  * for a message.
35  */
36 public interface Pull
37 {
38
39   /**
40    * The commonly used name to refer to this interface when it is used as an
41    * output.
42    */
43   String JavaDoc OUT_PULL_ITF_NAME = "out-pull";
44
45   /**
46    * The commonly used name to refer to this interface when it is used as an
47    * input.
48    */
49   String JavaDoc IN_PULL_ITF_NAME = "in-pull";
50
51   /**
52    * Asks for a message. If no message is available, the semantic of this method
53    * is left to the component implementing the interface. As an example, it can
54    * return <code>null</code> or block until a message is available.
55    *
56    * @param context a general purpose context map. can be <code>null</code>.
57    * @return the pulled message
58    * @throws PullException if an exception occurs.
59    */
60   Message pull(Map JavaDoc context) throws PullException;
61 }
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