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1   /*
2    * $Id: IdempotentSecureHashReceiver.java 7976 2007-08-21 14:26:13Z dirk.olmes $
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  
11  package org.mule.routing.inbound;
12  
13  import org.mule.transformers.simple.ByteArrayToHexString;
14  import org.mule.transformers.simple.SerializableToByteArray;
15  import org.mule.umo.MessagingException;
16  import org.mule.umo.UMOEvent;
17  import org.mule.umo.routing.RoutingException;
18  import org.mule.umo.transformer.TransformerException;
19  
20  import java.security.MessageDigest;
21  import java.security.NoSuchAlgorithmException;
22  
23  /**
24   * <code>IdempotentSecureHashReceiver</code> ensures that only unique messages are
25   * received by a component. It does this by calculating the SHA-256 hash of the
26   * message itself. This provides a value with an infinitesimally small chance of a
27   * collision. This can be used to filter message duplicates. Please keep in mind that
28   * the hash is calculated over the entire byte array representing the message, so any
29   * leading or trailing spaces or extraneous bytes (like padding) can produce
30   * different hash values for the same semantic message content. Care should be taken
31   * to ensure that messages do not contain extraneous bytes. This class is useful when
32   * the message does not support unique identifiers. This implementation provides for
33   * a persistent store of message hash values via the underlying file system and is
34   * suitable in failover environments.
35   */
36  
37  public class IdempotentSecureHashReceiver extends IdempotentReceiver
38  {
39      private static final String messageDigestAlgorithm = "SHA-256";
40  
41      private final SerializableToByteArray objectToByteArray = new SerializableToByteArray();
42      private final ByteArrayToHexString byteArrayToHexString = new ByteArrayToHexString();
43  
44      // @Override
45      protected Object getIdForEvent(UMOEvent event) throws MessagingException
46      {
47          try
48          {
49              MessageDigest md = MessageDigest.getInstance(messageDigestAlgorithm);
50              return byteArrayToHexString.transform(md.digest((byte[]) objectToByteArray.transform(event.getMessage()
51                  .getPayload())));
52          }
53          catch (NoSuchAlgorithmException nsa)
54          {
55              throw new RoutingException(event.getMessage(), event.getEndpoint(), nsa);
56          }
57          catch (TransformerException te)
58          {
59              throw new RoutingException(event.getMessage(), event.getEndpoint(), te);
60          }
61      }
62  }