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Asked: 2026-06-05T10:48:48+00:00

I am running into problems coding the FrameDecoder.decode() for a tcp netty client. protected

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I am running into problems coding the FrameDecoder.decode() for a tcp netty client.

protected Object decode(ChannelHandlerContext ctx, Channel channel,
        ChannelBuffer buffer) throws Exception {

In the above signature , the buffer is supposed to contain the bytes that need to be framed. But then why does an obejct have to be returned ? I am aware that if the returned object is null , this indicates that more data is required into this buffer, but what happens if I return a buffer with some unread bytes of a partial frame in it ? Will this be invoked with the more bytes added ?

Lets say a given invocation of decode() has a buffer with 100 bytes in it. Out of this 100 , there are 2 full frames of 25 and 55 bytes and partial frame of 20 bytes. Can I just read the first full frame ( of 25 bytes ) and return the buffer ( with 75 bytes in it – 1 full frame of 55 bytes and another 20 bytes of a partial frame ) ? Will this cause any bytes to be overwritten the next time decode is invoked ? or will it be ok for me to read the next frame ( of 55 bytes ) in the next invocation ?

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1 Answer

  1. Editorial Team

    You will return one frame per each call of decode. The FrameDecoder will continue to read and forward the read frames until you return null. The bytes left in the FrameDecoder will get saved and once a new ChannelBuffer was received both will get merged and the FrameDecoders decode(..) method will get called again.

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