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19
20 package org.apache.cayenne;
21
22 import org.apache.cayenne.graph.GraphEvent;
23
24 /**
25  * A listener of {@link org.apache.cayenne.DataChannel} lifecycle events. Changes
26  * related to an event are attached as a GraphDiff. If a listener needs to process these
27  * changes, the easiest way to do that is via GraphChangeHandler "visitor":
28  *
29  * <pre>
30  * public void graphChanged(GraphEvent event) {
31  * GraphChangeHandler handler = ..;
32  * event.getDiff().apply(handler);
33  * }
34  * </pre>
35  *
36  * @since 1.2
37  * @author Andrus Adamchik
38  */
39 public interface DataChannelListener {
40
41     /**
42      * Notifies implementing object of the changes that were performed to the object graph
43      * externally, not by one of the channel ObjectContexts.
44      */
45     void graphChanged(GraphEvent event);
46
47     /**
48      * Notifies implementing object that one of the channel ObjectContexts flushed its
49      * changes to the channel.
50      */
51     void graphFlushed(GraphEvent event);
52
53     /**
54      * Notifies implementing object that one of the channel ObjectContexts initiated a
55      * rollback.
56      */
57     void graphRolledback(GraphEvent event);
58 }
59
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