Netty + ProtoBuffer: A few communication messages for one connection

java static protocol-buffers netty
Sergii Zagriichuk picture Sergii Zagriichuk · Oct 18, 2011 · Viewed 13k times · Source

While reading the Netty tutorial, I've found a simple description of how to integrate Netty and Google Protocol Buffers. I've started to investigate its example (because there is no more information in the documentation) and written a simple application like the example local time application. But this example is using static initialization in PipeFactory Class, e.g.:

import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.handler.codec.protobuf.ProtobufDecoder;
import org.jboss.netty.handler.codec.protobuf.ProtobufEncoder;
import org.jboss.netty.handler.codec.protobuf.ProtobufVarint32FrameDecoder;
import org.jboss.netty.handler.codec.protobuf.ProtobufVarint32LengthFieldPrepender;

import static org.jboss.netty.channel.Channels.pipeline;

/**
 * @author sergiizagriichuk
 */
class ProtoCommunicationClientPipeFactory implements ChannelPipelineFactory {

    public ChannelPipeline getPipeline() throws Exception {
        ChannelPipeline p = pipeline();
        p.addLast("frameDecoder", new ProtobufVarint32FrameDecoder());
        p.addLast("protobufDecoder", new ProtobufDecoder(Communication.DataMessage.getDefaultInstance()));

        p.addLast("frameEncoder", new ProtobufVarint32LengthFieldPrepender());
        p.addLast("protobufEncoder", new ProtobufEncoder());

        p.addLast("handler", new ProtoCommunicationClientHandler());
        return p;
    }

}

(Please take a look at line p.addLast("protobufDecoder", new ProtobufDecoder(Communication.DataMessage.getDefaultInstance()));) and just one factory can be created (as I understand) for ClientBootstrap class, I mean bootstrap.setPipelineFactory() method. So, in this situation I can use ONE message to send to server and ONE message to receive from server and it is bad for me, and I think not just for me :( How can I use different messages to and from for just one connection? Perhaps I can create a few protobufDecoder like this

p.addLast("protobufDecoder", new ProtobufDecoder(Communication.DataMessage.getDefaultInstance()));
p.addLast("protobufDecoder", new ProtobufDecoder(Communication.TestMessage.getDefaultInstance()));
p.addLast("protobufDecoder", new ProtobufDecoder(Communication.SrcMessage.getDefaultInstance()));

or other techniques? Thanks a lot.

Answer

Sergii Zagriichuk picture Sergii Zagriichuk · Oct 18, 2011

I've found thread of author of netty in google groups and understood that I have to change my architecture or write my own decoder as I wrote above, So, Start to think what way will be easy and better.

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