Re: Heartbeat Interval Format

[Frank Mc Alinden]

Hi Ian

> Parsing an xpl message on a small chip, If you jump to byte 5, that
> single character (S, T or C) tells you the message class - byte 25 is
> always the start of the message source.. and so on.
>
> There are a whole bunch of fast navigation shortcuts in the message to
> save parsing the whole thing - when you have figured out it's a
> heartbeat, and you read a "{" after byte 10 that's the start
of the
> message body, and you can jump ahead a known number of bytes to get
the
> interval and so on.

Actually i check ALL characters received against my parser table .....The
message parsing section takes up almost the first 2k of program
memory....Decoding a 2 digit parameter looking for upper limits and lower
limits chews up valuable program space
As a fellow picer im sure you know what i mean....
Frank


----- Original Message -----
From: "Ian Lowe" <<a
href="/group/ukha_xpl/post?postID=GrQ3nc26Caa8S0XO1oaDDaZfs39_sUG9sV0zfzv-iimWs19SnnPgnKUvTNY9t8kUL8UAiPZOxs37RivNXcY">ian@w...</a>>
To: <<a
href="/group/ukha_xpl/post?postID=J07nqCbOQG4hMztaipA0WlVUQM8vi1otoe6huzZErbZRk1tqBXTc5DZSXcReMD4ZhzxeC00AIJO5UJXnCQ4gjO4">ukha_xpl@xxxxxxx</a>>
Sent: Sunday, March 21, 2004 9:49 PM
Subject: RE: [ukha_xpl] Heartbeat Interval Format


> Yeah, it is - and that's proven to be a nice network friendly level.
>
> What I think frank is getting at is that this:
>
> Parsing an xpl message on a small chip, If you jump to byte 5, that
> single character (S, T or C) tells you the message class - byte 25 is
> always the start of the message source.. and so on.
>
> There are a whole bunch of fast navigation shortcuts in the message to
> save parsing the whole thing - when you have figured out it's a
> heartbeat, and you read a "{" after byte 10 that's the start
of the
> message body, and you can jump ahead a known number of bytes to get
the
> interval and so on.
>
> People can change the interval via xplhal manager - if they set it to
a
> single digit value, then the positions of the heartbeat tags within
the
> message are fixed to a greater extent.. if the number the user enters
is
> double digit, then that's harder to parse.
>
> I think what I'm suggesting here is to place bounds on the value that
> the user can specify for "interval=". The default is 5
minutes at
> present, and that's working well. I'd suggest a minimum of 2 and a
> maximum of 9 - especially as the expiration in xplhal is based on the
> heartbeat interval - making it higher than 9 would have dead devices
> (that hadn't hbeat.end'ed) hanging around for ages.
>
> Ian.
>
> -----Original Message-----
> From: Tony Tofts [mailto:<a
href="/group/ukha_xpl/post?postID=ESEwDIGXHcG8y2B_6IVttu4nedrSfvAPe3Uo2bRI8FvbVE_AZ1TTSlPLwbwOJ7zKqcPg15A">tony@x...</a>]
> Sent: 21 March 2004 10:32
> To: <a
href="/group/ukha_xpl/post?postID=J07nqCbOQG4hMztaipA0WlVUQM8vi1otoe6huzZErbZRk1tqBXTc5DZSXcReMD4ZhzxeC00AIJO5UJXnCQ4gjO4">ukha_xpl@xxxxxxx</a>
> Subject: RE: [ukha_xpl] Heartbeat Interval Format
>
> > In my opinion, a better solution is to set the maximum
> > interval for the device at 9 minutes.
>
> Isn't the default still 5 minutes?
>
> And a device is considered dead if doesn't beat after 2 * interval + 1
> minutes?
>
> Thanks
> Tony
>
>
>
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