Re: Suggestions for custom application-layer protocol?

From: Glyn Davies (gryn_at_riffraff.plig.net)
Date: 05/27/05 

Date: Fri, 27 May 2005 10:55:40 +0000 (UTC)

In comp.os.linux.embedded Grant Edwards <grante@visi.com> wrote:
> On 2005-05-26, Mark <mark_2811nospam@excite.com> wrote:

>> I expect I will end up with a text-based protocol, with a header
>> that indicates the number of bytes in the payload.

> If you're using a text-based protocol, you don't nead a header
> with a payload count to tell you where the message ends. Use
> an end-of-message character or string. The cr/lf pair is used
> as the end-of-message delimiter by a lot of text-based
> runs-on-top of TCP protocols. That approach works wonderfully
> with line-oriented high-level text-handling libraries and
> utilties -- you can do all sorts of useful stuff using nothing
> but a few utilities like netcat, expect, and so on.

> I've also seen protocols that use STX/ETX to frame messages,
> and that works nicely as well, but isn't as compatible with
> pre-existing utilities.

<snip>

Most STX/ETX stuff I have seen was over serial comms.
Not seen it in use over TCP - except where there was an annex box
feeding out a bunch of serial lines converted to TCP.

Glyn 

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