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1   /***
2    *
3    * Copyright 2004 Hiram Chirino
4    *
5    *  Licensed under the Apache License, Version 2.0 (the "License");
6    *  you may not use this file except in compliance with the License.
7    *  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   */
17  package org.activeio.filter;
18  
19  import java.io.IOException;
20  
21  import org.activeio.AsynchChannel;
22  import org.activeio.FilterAsynchChannel;
23  import org.activeio.Packet;
24  
25  /***
26   * This PacketAggregatingAsynchChannel can be used when the client is sending a
27   * 'record' style packet down the channel stack and needs receiving end to
28   * receive the same 'record' packets.
29   * 
30   * This is very usefull since in general, a channel does not garantee that a
31   * Packet that is sent down will not be fragmented or combined with other Packet
32   * objects.
33   * 
34   * This {@see org.activeio.AsynchChannel} adds a 4 byte header
35   * to each packet that is sent down.
36   * 
37   * @version $Revision$
38   */
39  final public class PacketAggregatingAsynchChannel extends FilterAsynchChannel {
40  
41      private final PacketAggregator aggregator = new PacketAggregator() {
42          protected void packetAssembled(Packet packet) {
43              getAsynchChannelListener().onPacket(packet);
44          }
45      };
46      
47      public PacketAggregatingAsynchChannel(AsynchChannel next) {
48          super(next);
49      }
50  
51      public void onPacket(Packet packet) {
52          try {
53              aggregator.addRawPacket(packet);
54          } catch (IOException e) {
55              getAsynchChannelListener().onPacketError(e);
56          }
57      }    
58      
59      public void write(Packet packet) throws IOException {
60          getNext().write(aggregator.getHeader(packet));
61          getNext().write(packet);
62      }
63  
64  }