Typecasting Problem Using Netty and Google Protobuf

[Akash Gangil]

*
Hi,

Explaining the problem in nutshell when I typecast the message (received by
the client) to the message type (of protocol buffer class) in the server I
get this error WARNING: Unexpected exception from downstream.
java.lang.ClassCastException:
org.jboss.netty.buffer.BigEndianHeapChannelBuffer cannot be cast to
org.jboss.netty.example.echo.MessageProtos$Packet
**
Packet p = (Packet) e.getMessage() ,
**
where Packet is the Message class generated via google Proc Buffers
**

*
*
*
*SGClienthandler.java : *
*
*

 public void send(String message_type, String message_to_send, int
message_id){
 Packet p = Packet.newBuilder()
.setPacketId(message_id)
.setPacketType(message_type)
        .setPacketContent(message_to_send).build();
 try {
            channel.write(p);
            System.out.print("Message was sent to this channel : " +
channel);
}
catch (Exception e) {
 System.out.println(" In send() ");
e.printStackTrace();
}
 }

*EchoServerhandler.java :*

 @Override
      public void messageReceived(
              ChannelHandlerContext ctx, MessageEvent e) {
      System.out.print("Message Received : " + e.getMessage());
      Packet req = (Packet) e.getMessage();
      System.out.print("Packet Id received  :  " + req.getPacketId());
      System.out.print("Packet Type received  :  " + req.getPacketType());
      System.out.print("Packet Content received  :  " +
req.getPacketContent());
     }



The Pipeline factory of both the client and server namely  : *SGPipelineFactory
and EchoServerPipelineFactory *have same
encoding and decoding handlers apart from the specific handlers related to
their logic.

     // Decoders
        pipeline.addLast("frameDecoder", new
ProtobufVarint32FrameDecoder());
        pipeline.addLast("protobufDecoder", new
ProtobufDecoder(Packet.getDefaultInstance()));

        // Encoder
        pipeline.addLast("frameEncoder", new
ProtobufVarint32LengthFieldPrepender());
        pipeline.addLast("protobufEncoder", new ProtobufEncoder());






*Error :*

WARNING: Unexpected exception from downstream.
java.lang.ClassCastException:
org.jboss.netty.buffer.BigEndianHeapChannelBuffer cannot be cast to
org.jboss.netty.example.echo.MessageProtos$Packet
 at
org.jboss.netty.example.echo.EchoServerHandler.messageReceived(EchoServerHandler.java:63)

The line 63 is in red.


Would be great if I can get some pointers.

-- 
Akash
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