Text Protocol -- Variable length, variable number of lines

[Trustin Lee (이희승)]

Hi,

I would simply extend DelimiterBasedFrameDecoder and override its
decode(...) method like the following:

    private final StringBuilder buf = new StringBuilder();
    private int lineCount;

    @Override
    protected Object decode(...) {
        String frame = super.decode(...);
        if (frame == null) {
            return null;
        }
        lineCount ++;
        buf.append(frame);
        buf.append("\r\n");
        if (lineCount == N) {
            lineCount = 0;
            String realFrame = buf.toString();
            buf.delete(0, buf.length());
            return realFrame;
        }
        return null;
    }

HTH

— Trustin Lee, http://gleamynode.net/

On Sun, Nov 8, 2009 at 7:54 AM, venky10 <vsayyagari at gmail.com> wrote:
>
> Hi,
>
> In the telnet/server case each newline would trigger a MessageEvent. In my
> case it would be inefficient, I intend to handle MessageEvent after an X
> number (which is variable) of lines have been available for upstream
> processing to the StreamDecoder.  If I simple call --
>
>  public void messageReceived(
>           ChannelHandlerContext ctx, MessageEvent e) {
>            // Cast to a String first.
>         // We know it is a String because we put some codec in
> TelnetPipelineFactory.
>          String several_lines_protocol_msg= (String) e.getMessage();
>        :::::
> }
>
>  there is no guarantee that all the lines of the protocol packet have been
> captured in
> "several_lines_protocol_msg". Or is it the case that if FrameDecoder is not
> supplied the message received will be all the bytes available in the stream
> ?
>
> Thanks a lot.
> Venkay
>
>
> Trustin Lee wrote:
>>
>> Hi Venky,
>>
>> DelimiterBasedFrameDecoder is perhaps what you are looking for.  Also,
>> please refer to the telnet client/server example.
>>
>> HTH
>>
>> — Trustin Lee, http://gleamynode.net/
>>
>>
>>
>> On Sat, Nov 7, 2009 at 7:11 AM, venky10 <vsayyagari at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> I am a newbie to Netty.
>>> I have text protocol to decode. It has variable number of lines, all
>>> delimited by 'newline'.
>>> There is no other end-of-frame delimiter. I am assuming it would be most
>>> efficient  to read the entire frame till there are no more lines to be
>>> read
>>> on single MessageEvent.
>>>
>>> What is the best approach ?
>>>
>>> Thanks,
>>> Venky
>>> --
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>>
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>
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