Netty - Send failed: UnsupportedOperationException: unsupported message type

Question

I am writing server-client app using Netty 4.1.9.

Recently I successfully made communication using ByteBuf. Then tried with String and succeed again.

But with last step I wanted to send custom Object and there is my problem:

Send failed: java.lang.UnsupportedOperationException: unsupported message type: GIdPacket (expected: ByteBuf, FileRegion)

Some code parts

Server:

ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
    .channel(NioServerSocketChannel.class)
    .childHandler(new ChannelInitializer<SocketChannel>() {
        @Override
        public void initChannel(SocketChannel ch) throws Exception {
             ch.pipeline().addLast(new ObjectDecoder(Integer.MAX_VALUE, ClassResolvers.cacheDisabled(null)));
             ch.pipeline().addLast(new ObjectEncoder());
             ch.pipeline().addLast(new ServerHandler());
             ch.pipeline().addLast(loggingHandler);
         }
     })
    .option(ChannelOption.SO_BACKLOG, 128)
    .childOption(ChannelOption.SO_KEEPALIVE, true)
    .option(ChannelOption.AUTO_READ, true);

ChannelFuture f = b.bind(port).sync();

ServerHandler:

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception
{
    System.out.println("CHANNEL >> channelActive fired");
    clientData = new ClientData(Server.newId(), ctx.channel());
    Server.clients.put(clientData.id, clientData);

    GIdPacket packet = new GIdPacket(/*some init atr*/);

    ChannelFuture cf = ctx.writeAndFlush(packet);
    if (!cf.isSuccess()) {
        System.out.println("Send failed: " + cf.cause());
    }

    Log.out(packet.toString());
}

So, I tried many different options. I spent much time on that and I didn't found solution. Any help appreciated.

Feedforward · Accepted Answer · 2017-04-30 16:37:50Z

2

Looks like GIdPacket doesn't implement Serializable interface. According to the docs, ObjectEncoder supports only serializable objects: class ObjectEncoder extends MessageToByteEncoder<Serializable>.

By the way, you're trying to check channelFuture.isSuccess() immediately after execution writeAndFlush(..). Because Netty is completly asynchronous, this test will fail because channelFuture is neither successful nor failed yet. You must wait until CF is completed by calling cf.await() or cf.awaitUninterruptibly().

answered Apr 30, 2017 at 16:37

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2 Comments

Shaq Over a year ago

So like you said, I made my Objects serializable and it works now. Grats!

Norman Maurer Over a year ago

Never call cf.await* in the EventLoop thread. You should register a listener to the future.

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