LengthFieldBasedFrameDecoder

[hezjing]

Hi Trustin

In my case, the length field is the size of the payload (excluding the
header).

If I read the Javadoc correctly, the LengthFieldBasedFrameDecoder is
applicable when the length field is the size of the header and payload
right?

:-)

On Mon, Sep 21, 2009 at 9:39 AM, Trustin Lee (이희승) <trustin at gmail.com>wrote:

> Hi Hez,
>
> Thanks for closing this thread with a good answer and sorry that I'm late.
>
> Do you find the Javadoc of LengthFieldBasedFrameDecoder difficult to
> understand?  I thought your use case is explained already there.  Let
> me know what you think so that we can improve the documentation.
>
> Cheers
>
> — Trustin Lee, http://gleamynode.net/
>
>
>
> On Sun, Sep 20, 2009 at 9:12 PM, hezjing <hezjing at gmail.com> wrote:
> > Hi Mike
> > Hmmm ... do you mean the example of the frame like the following?
> > <-- HEADER 20 bytes --><-- PAYLOAD 14 bytes -->
> > +-------+---------+----+-----------------------+
> > |       | Length  |    | Payload               |
> > |       | 0x000C  |    |                       |
> > +-------+---------+----+-----------------------+
> > Total frame size is 34 bytes.
> > <-- HEADER 20 bytes --><-- PAYLOAD 100 bytes -->
> > +-------+--------+-----+------------------------+
> > |       | Length |     | Payload                |
> > |       | 0x0064 |     |                        |
> > +-------+--------+-----+------------------------+
> > Total frame size is 120 bytes.
> >
> >
> > On Sun, Sep 20, 2009 at 1:41 AM, Mike McGrady <
> mmcgrady at topiatechnology.com>
> > wrote:
> >>
> >> Could you include an example write with this?  The two together, I
> >> suspect, will be most helpful to many people, including me.
> >> Mike
> >> On Sep 19, 2009, at 8:11 AM, hezjing wrote:
> >>
> >> Hi
> >> To close this thread, my solution is to extends FrameDecoder like the
> >> following code:
> >> @ChannelPipelineCoverage("all")
> >> public class MyFrameDecoder extends FrameDecoder {
> >>     @Override
> >>     protected Object decode(ChannelHandlerContext ctx, Channel channel,
> >> ChannelBuffer buf) throws Exception {
> >>         // the length field is at 3rd and 4th octet
> >>         if (buf.readableBytes() < 4) {
> >>             return null;
> >>         }
> >>         // The length field is in the buffer.
> >>         buf.markReaderIndex();
> >>         ...
> >>         // Read the length field (the payload size)
> >>         int length = buf.readUnsignedShort();
> >>         // The actual frame size is header (20) + payload size
> >>         length += 20;
> >>         buf.resetReaderIndex();
> >>         if (buf.readableBytes() < length) {
> >>             return null;
> >>         }
> >>         ChannelBuffer frame = buf.readBytes(length);
> >>         return frame;
> >>     }
> >> }
> >>
> >> Thank you!
> >>
> >> On Thu, Sep 10, 2009 at 9:23 PM, hezjing <hezjing at gmail.com> wrote:
> >>>
> >>> Hi
> >>> I have a message containing a fixed length header of 20 bytes, followed
> >>> by a payload of variable length.
> >>> The header contains a 2 bytes length field, indicating the length of
> the
> >>> payload (excluding the header).
> >>> For example if the message has 10 bytes payload, then the entire frame
> >>> length is 30 bytes (20 bytes header + 10 bytes of payload),
> >>> and the length field is 10.
> >>> May I know what is the parameter to
> create LengthFieldBasedFrameDecoder?
> >>>
> >>> Thank you!
> >>>
> >>> --
> >>>
> >>> Hez
> >>
> >>
> >>
> >> --
> >>
> >> Hez
> >> _______________________________________________
> >> netty-users mailing list
> >> netty-users at lists.jboss.org
> >> https://lists.jboss.org/mailman/listinfo/netty-users
> >>
> >> Mike McGrady
> >> Principal Investigator AF081-028 AFRL SBIR
> >> Senior Engineer
> >> Topia Technology, Inc.
> >> 1.253.720.3365
> >> mmcgrady at topiatechnology.com
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> netty-users mailing list
> >> netty-users at lists.jboss.org
> >> https://lists.jboss.org/mailman/listinfo/netty-users
> >>
> >
> >
> >
> > --
> >
> > Hez
> >
> > _______________________________________________
> > netty-users mailing list
> > netty-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/netty-users
> >
> >
>
> _______________________________________________
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>



-- 

Hez
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