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1   /*
2    * $Id: EventCorrelatorCallback.java 11531 2008-04-08 15:34:34Z rossmason $
3    * --------------------------------------------------------------------------------------
4    * Copyright (c) MuleSource, Inc.  All rights reserved.  http://www.mulesource.com
5    *
6    * The software in this package is published under the terms of the CPAL v1.0
7    * license, a copy of which has been included with this distribution in the
8    * LICENSE.txt file.
9    */
10  package org.mule.routing;
11  
12  import org.mule.routing.inbound.EventGroup;
13  import org.mule.api.MuleMessage;
14  import org.mule.api.MuleEvent;
15  import org.mule.api.routing.RoutingException;
16  
17  /**
18   * A callback used to allow pluggable behaviour when correlating events
19   */
20  public interface EventCorrelatorCallback
21  {
22      /**
23       * Determines if the event group is ready to be aggregated. if the group is ready
24       * to be aggregated (this is entirely up to the application. it could be
25       * determined by volume, last modified time or some oher criteria based on the
26       * last event received).
27       *
28       * @param events The current event group received by the correlator
29       * @return true if the group is ready for aggregation
30       */
31      public boolean shouldAggregateEvents(EventGroup events);
32  
33      /**
34       * This method is invoked if the shouldAggregate method is called and returns
35       * true. Once this method returns an aggregated message, the event group is
36       * removed from the router.
37       *
38       * @param events the event group for this request
39       * @return an aggregated message
40       * @throws AggregationException if the aggregation fails. in this scenario the
41       *                              whole event group is removed and passed to the exception handler
42       *                              for this component
43       */
44      public MuleMessage aggregateEvents(EventGroup events) throws RoutingException;
45  
46  
47      /**
48       * Creates the event group with a specific correlation size based on the Mule
49       * Correlation support
50       *
51       * @param id    The group id
52       * @param event the current event
53       * @return a new event group of a fixed size
54       */
55      public EventGroup createEventGroup(MuleEvent event, Object id);
56  }