01 /*
02 *
03 * Licensed to the Apache Software Foundation (ASF) under one
04 * or more contributor license agreements. See the NOTICE file
05 * distributed with this work for additional information
06 * regarding copyright ownership. The ASF licenses this file
07 * to you under the Apache License, Version 2.0 (the
08 * "License"); you may not use this file except in compliance
09 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 *
20 */
21 package org.apache.qpid.client.failover;
22
23 /**
24 * FailoverException is used to indicate that a synchronous request has failed to receive the reply that it is waiting
25 * for because the fail-over process has been started whilst it was waiting for its reply. Synchronous methods generally
26 * raise this exception to indicate that they must be re-tried once the fail-over process has completed.
27 *
28 * <p/><table id="crc"><caption>CRC Card</caption>
29 * <tr><th> Responsibilities <th> Collaborations
30 * <tr><td> Used to indicate failure of a synchronous request due to fail-over.
31 * </table>
32 *
33 * @todo This exception is created and passed as an argument to a method, rather than thrown. The exception is being
34 * used to represent an event, passed out to other threads. Use of exceptions as arguments rather than as
35 * exceptions is extremly confusing. Ideally use a condition or set a flag and check it instead.
36 * This exceptions-as-events pattern seems to be in a similar style to Mina code, which is not pretty, but
37 * potentially acceptable for that reason. We have the option of extending the mina model to add more events
38 * to it, that is, anything that is interested in handling failover as an event occurs below the main
39 * amq event handler, which knows the specific interface of the qpid handlers, which can pass this down as
40 * an explicit event, without it being an exception. Add failover method to BlockingMethodFrameListener,
41 * have it set a flag or interrupt the waiting thread, which then creates and raises this exception.
42 */
43 public class FailoverException extends Exception
44 {
45 public FailoverException(String message)
46 {
47 super(message);
48 }
49 }
|