Create netcat style consumer with Apache Camel and netty4: route - spring

Question

I try to create a tcp receiver which can get data over a certain port and store it into a file. I use Apache Camel 2.16.1, Spring Boot 1.3.0-RELEASE and netty 4.0.33 for this.
My setup is like that described in the camel-spring-boot starter, the route definition is this:
#Component
public class Routes {
#Bean
RoutesBuilder myRouter() {
return new RouteBuilder() {
#Override
public void configure() throws Exception {
from( "netty4:tcp://192.168.0.148:10001?sync=false&allowDefaultCodec=false&decoder=#decoder")
.to("file:/temp/printjobs");
}
};
}
}
I created a decoder that looks like this:
public class RawPrinterDecoder extends MessageToMessageDecoder<ByteBuf> {
#Override
protected void decode(ChannelHandlerContext ctx, ByteBuf msg,
List<Object> out) throws Exception {
byte[] array = new byte[msg.readableBytes()];
msg.getBytes(0, array);
String string = new String(array);
out.add(string);
System.out.println("Received " + msg.readableBytes()
+ " in a buffer with maximum capacity of " + msg.capacity());
System.out.println("50 first bytes I received: "
+ string.substring(0, 50));
}
}
Data is sent by using this command:
cat binaryfile | nc 192.168.0.148 10001
The route is built but when I use it I am unable to get the former binaryfile in its original shape and rather receive several blocks of data:
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 1024 in a buffer with maximum capacity of 1024
Received 16384 in a buffer with maximum capacity of 16384
Received 16384 in a buffer with maximum capacity of 16384
Received 16384 in a buffer with maximum capacity of 16384
Received 5357 in a buffer with maximum capacity of 16384
(As you can see my original file is processed in blocks of increasing size and it 70839 byte in size)
The received blocks are each stored in a separate file because I am not able to join the parts:
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-1
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-3
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-5
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-7
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-9
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-11
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-13
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-15
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-17
24.11.2015 23:47 1.024 ID-Tower-53867-1448405258593-0-19
...
How can I identify the first and last block and join them in the decoder ? I made an approach which involved getMaxMessagesPerRead() but this returns 16 and my file is split into 20 blocks of data.