NewDataStrategy


1   /**
2    * PETALS - PETALS Services Platform.
3    * Copyright (c) 2005 EBM Websourcing, http://www.ebmwebsourcing.com/
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 2.1 of the License, or (at your option) any later version.
9    * This library is distributed in the hope that it will be useful,
10   * but WITHOUT ANY WARRANTY; without even the implied warranty of
11   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   * Lesser General Public License for more details.
13   *
14   * You should have received a copy of the GNU Lesser General Public
15   * License along with this library; if not, write to the Free Software
16   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17   *
18   * -------------------------------------------------------------------------
19   * $Id : $ 
20   * -------------------------------------------------------------------------
21   */
22  package org.objectweb.petals.binding.xquarebc.listeners;
23  
24  import javax.xml.transform.Source  ;
25  
26  /**
27   * This interface represents a strategy for detecting "new data",
28   * getting it (as XML) and updating what data is known.
29   * 
30   * Implementations are typically instanciated from a factory
31   * each time new data must be detected and processed, so it may
32   * (it is even advised) have a state.
33   * 
34   * @version $Rev: 250 $Date: {date}
35   * @since Petals 1.0
36   * @author Marc Dutoo - Open Wide
37   *
38   */
39  public interface NewDataStrategy {
40  
41      /**
42       * Detects new data. May save the resulting information
43       * for later use in getNewData() and updateDataKnown().
44       * @return true if there is new data
45       * @throws Exception
46       */
47      public abstract boolean detectNewData() throws Exception  ;
48  
49      /**
50       * Queries for the detected new data and returns them as
51       * a formatted XML source. 
52       * @return
53       * @throws Exception
54       */
55      public abstract Source   getNewData() throws Exception  ;
56  
57      /**
58       * Updates the persistent knwoledge of new data found so the
59       * new time the strategy is used, it will be old data.
60       * @throws Exception
61       */
62      public abstract void updateDataKnown() throws Exception  ;
63  }
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