How to handle exception in decoders/handlers?

[infectedrhythms]

There lots of things to grasp here but would this work?

public class MPIPipelineFactory implements ChannelPipelineFactory {

	//@Override
	public ChannelPipeline getPipeline() throws Exception {

		ChannelPipeline pipeline = Channels.pipeline();

        pipeline.addLast("framer", new MyDecoder(5));
        pipeline.addLast("handler", new MyHandler());
        pipeline.addLast("stringEncoder", new StringEncoder("UTF-8"));
		
		return pipeline;
	}
}

And then in exceptionCaught(... ExceptionEvent e)
{
e.getChannel.write("...");
}




infectedrhythms wrote:
> 
> Is there a simple sample to follow?
> 
> Trustin Lee (via Nabble) wrote:
>> You need an encoder.
>>
>> On 2009-06-20 오전 3:21, infectedrhythms wrote:
>>
>> >
>> > Ok so now the exception is the last handler.
>> >
>> > But how do I write to the socket as
>> >
>> > @Override
>> > public void exceptionCaught(ChannelHandlerContext ctx, 
>> ExceptionEvent e) {
>> >
>> > e.getCause().printStackTrace();
>> >
>> > e.getChannel().write("Test");
>> >
>> >
>> > //ChannelFuture cf = ch.write("Test");
>> >
>> > //cf.addListener(ChannelFutureListener.CLOSE);
>> > //ch.close();
>> > }
>> >
>> > throws...
>> >
>> >
>> > java.lang.ClassCastException: java.lang.String cannot be cast to
>> > org.jboss.netty.buffer.ChannelBuffer
>> > at
>> > 
>> org.jboss.netty.channel.socket.nio.NioWorker.writeUnfair(NioWorker.java:438) 
>>
>> > at 
>> org.jboss.netty.channel.socket.nio.NioWorker.write(NioWorker.java:411)
>> > at
>> > 
>> org.jboss.netty.channel.socket.nio.NioServerSocketPipelineSink.handleAcceptedSocket(NioServerSocketPipelineSink.java:138) 
>>
>> > at
>> > 
>> org.jboss.netty.channel.socket.nio.NioServerSocketPipelineSink.eventSunk(NioServerSocketPipelineSink.java:78) 
>>
>> > at org.jboss.netty.channel.Channels.write(Channels.java:626)
>> > at org.jboss.netty.channel.Channels.write(Channels.java:592)
>> > at 
>> org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:203)
>> > at
>> > 
>> com.rbs.threedsecure.mpi.services.broker.ThreeDHandler.exceptionCaught(ThreeDHandler.java:51) 
>>
>> > at
>> > 
>> com.rbs.threedsecure.mpi.services.broker.ThreeDHandler.handleUpstream(ThreeDHandler.java:32) 
>>
>> > at
>> > 
>> org.jboss.netty.handler.codec.frame.FrameDecoder.exceptionCaught(FrameDecoder.java:194) 
>>
>> > at 
>> org.jboss.netty.channel.Channels.fireExceptionCaught(Channels.java:440)
>> > at
>> > 
>> org.jboss.netty.channel.AbstractChannelSink.exceptionCaught(AbstractChannelSink.java:59) 
>>
>> > at 
>> org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:293)
>> > at 
>> org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:280)
>> > at
>> > 
>> org.jboss.netty.channel.socket.nio.NioWorker.readIntoHeapBuffer(NioWorker.java:300) 
>>
>> > at
>> > 
>> org.jboss.netty.channel.socket.nio.NioWorker.processSelectedKeys(NioWorker.java:254) 
>>
>> > at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:163)
>> > at
>> > 
>> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
>>
>> > at
>> > 
>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
>>
>> > at java.lang.Thread.run(Thread.java:619)
>> >
>> >
>> >
>> > Trustin Lee wrote:
>> >>
>> >> Hi,
>> >>
>> >> It seems like one of the handlers in your pipeline closes the 
>> connection
>> >> on an exceptionCaught event (perhaps the last handler.)  I would catch
>> >> the exception in the last handler and send the error message there
>> >> rather than sending it in the decoder, because it's often a good 
>> idea to
>> >> separate protocol state from codec.
>> >>
>> >> HTH,
>> >> Trustin
>> >>
>> >> On 2009-06-20 오전 2:42, infectedrhythms wrote:
>> >>>
>> >>> Hi, I have implemented a simple decoder and it works fine.
>> >>>
>> >>> Now if there is an error I want to throw an exception catch and reply
>> >>> back
>> >>> to the client, kind of like an HTTP 500 error.
>> >>>
>> >>> So if the decoder fails it should write back to the client the 
>> error that
>> >>> occurred.
>> >>>
>> >>> @Override
>> >>> protected Object decode(ChannelHandlerContext ctx, Channel channel,
>> >>> ChannelBuffer buf) throws Exception {
>> >>>
>> >>> ... do stuff here...
>> >>>
>> >>> throw new Exception("Errrorrrr!");
>> >>> }
>> >>>
>> >>> @Override
>> >>> public void exceptionCaught(ChannelHandlerContext ctx, 
>> ExceptionEvent e)
>> >>> throws Exception {
>> >>>
>> >>> super.exceptionCaught(ctx, e);
>> >>>
>> >>> e.getChannel().write("Damn it Jim!"); <-- Throws a
>> >>> ClosedChannelException
>> >>>
>> >>> }
>> >>
>> >>
>> >> --
>> >> — Trustin Lee, http://gleamynode.net/
>> >>
>> >>
>> >>  
>> >> _______________________________________________
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>> >>
>> >>
>> >
>>
>> -- 
>> — Trustin Lee, http://gleamynode.net/
>>
>>
>>
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>> Trustin Lee, Principal Software Engineer, JBoss, a division of Red Hat
>> -- 
>> what we call human nature is actually human habit
>> -- 
>> http://gleamynode.net/
>>
>>
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> 
> 
> 
> 

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