01: /**
02: * Sequoia: Database clustering technology.
03: * Copyright (C) 2006 Continuent, Inc.
04: * Contact: sequoia@continuent.org
05: *
06: * Licensed under the Apache License, Version 2.0 (the "License");
07: * you may not use this file except in compliance with the License.
08: * You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing, software
13: * distributed under the License is distributed on an "AS IS" BASIS,
14: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15: * See the License for the specific language governing permissions and
16: * limitations under the License.
17: *
18: * Initial developer(s): Emmanuel Cecchet.
19: * Contributor(s): ______________________.
20: */package org.continuent.sequoia.controller.virtualdatabase.protocol;
21:
22: import java.io.Serializable;
23:
24: import org.continuent.hedera.common.Member;
25: import org.continuent.sequoia.controller.virtualdatabase.DistributedVirtualDatabase;
26:
27: /**
28: * This interface defines a DistributedVirtualDatabaseMessage
29: *
30: * @author <a href="mailto:emmanuel.cecchet@continuent.com">Emmanuel Cecchet</a>
31: * @version 1.0
32: */
33: public abstract class DistributedVirtualDatabaseMessage implements
34: Serializable {
35:
36: /**
37: * Single threaded part of the handler that will execute in mutual execution
38: * in the total order delivery thread of the group communication.
39: * <p>
40: * NEVER BLOCK IN THIS HANDLER !!!
41: *
42: * @param dvdb the local instance of the distributed virtual database
43: * @param sender the message sender
44: * @return an optional value to be passed to the multithreaded handler
45: */
46: public abstract Object handleMessageSingleThreaded(
47: DistributedVirtualDatabase dvdb, Member sender);
48:
49: /**
50: * Multi-threaded part of the message handler.
51: *
52: * @param dvdb the local instance of the distributed virtual database
53: * @param sender the message sender
54: * @param handleMessageSingleThreadedResult value returned by the single
55: * threaded handler
56: * @return a Serializable object to be returned to the sender
57: */
58: public abstract Serializable handleMessageMultiThreaded(
59: DistributedVirtualDatabase dvdb, Member sender,
60: Object handleMessageSingleThreadedResult);
61:
62: /**
63: * Cancel the message in a "best effort"-basis. Should try to undo message
64: * side-effects and clean-up reources.
65: *
66: * @param dvdb the local instance of the distributed virtual database
67: */
68: public void cancel(DistributedVirtualDatabase dvdb) {
69: // Does nothing by default.
70: }
71:
72: }
|