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Problem with netty4:udp and udpByteArrayCodec=true


First, a couple of thank yous several weeks in the making:

Thank you to Claus (as always) for help regarding replacing camel-rabbitmq with a custom class.  Indeed, I only needed to do a write.  So using 'to("bean:myBean?method=process)' worked perfectly.

Thank you to Zoran for advice on Spring injection vs. Component Scan.  I never was able to get beans in the Spring config auto-wired, so I had to do the manual steps of getting the Spring context, getting the bean, and then setting the bean where it needed to be.  A bit ugly, but only a few lines of code.  It works, so I'm leaving it alone for now.

Now on to my most recent hurdle...

I'm trying to write a protobuf over UDP to a server (a non-Camel app written in C++) expecting it serialized into a byte array.

The problem is that the only write that makes it to the server seems to be serialized incorrectly.  Conversely, when I think I've correctly serialized it, nothing seems to get written to the wire.

The route below is the one that makes it to the server.  When I do a tcpdump on the server's side, however, I can see that the payload is about 35-40 bytes bigger than what the protobuf says its serialized size should be:

from("direct:protobuf")
     .marshal().protobuf()
     .convertBodyTo(String.class, "UTF-8")  // needed, else to(netty4:udp) hangs
     .to("netty4:udp://host:port?udpConnectionlessSending=true&sync=false");

I immediately recognized this as probably being a "default codec" problem, similar to what I recently encountered when I was writing some JSON over UDP with netty4.

So I tried the following, but nothing was written over the wire:

     .to("netty4:udp://host:port?udpConnectionlessSending=true&sync=false&allowDefaultCodec=false");

I tried about a half dozen combinations: marshalling / not marshalling, convertBodyTo() / no convertBodyTo(), allowDefaultCode = false / true, etc.

Nothing was working.  And then I somehow stumbled upon 'udpByteArrayCodec' in the docs and thought I'd found it!

However, this didn't send anything to the wire either:

     .to("netty4:udp://host:post?udpConnectionlessSending=true&sync=false&udpByteArrayCodec=true");

Neither did this:

     .to("netty4:udp://host:port?udpConnectionlessSending=true&sync=false&udpByteArrayCodec=true&allowDefaultCodec=false");

Only the original route resulted in *anything* being written across the wire for the server to see:

     .to("netty4:udp://host:port?udpConnectionlessSending=true&sync=false");

Does anyone know what else I should try?

I have never had any luck trying to install a non-default encoder/decoder, but in this case I don't think I even need it.  I just need to serialize the protobuf to a byte array, and it seems that this 'udpByteArrayCodec' is exactly what I need.  So how should I be using it?  What could be preventing anything from appearing over the wire?

Thank you so much as always!

Ron