[OZAPRS] VK email server

[John Williams]

The way I understand it is that aprs messages contain 0 - 67 chars
in the message field.

If your aprs client allows you to go beyond 67 chars then it places the
additional text
in another packet.

The aprs email server would then need to know if the packet is a
continuation packet for the 
same email address or another message addressed to another email address.

I have not tried to send an email longer than the allowed length to the
other servers. Do the 
current servers process such messages.

Richard VK3JFK suggested the > char as an indication that more text was to
follow. 

Aprs uses un-numbered info frames so the only possible way to determine
packet sequence is 
via the ack field.  This is not necessarily numeric but if it is
lexigraphically sortable then this field 
can be used to assemble received packets in sequence. 

You need to consider that packets may not arrive in order.  Packets might
be sent by other 
stations and seen by the server while you are still sending your message
text.

What I currently do is check that the first part of the message  is an
attempt at a valid email 
address. If it is, grab it then the message text and send an ack to the
sender. The email is then 
sent. 

Anything without a valid email address in the beginning of the message is
rejected.

Using a continuation character would then let the server know to expect
more text.
Then we would need an end of message sequence. FBB uses /ex but it really
could be 
anything
unique.

I would be interested in any ideas of way around not using a continuation
flag and end of 
message flag.  Given that you cant guarantee the arrival order of packets
or the intention of the 
people sending messages.

Cheers
John
VK5ZTY


On 29 Mar 2004 at 12:34, Robert Bruninga wrote:

> >>> "John Williams" <vk5zty at bigpond.com> 3/27/04 9:50:53 PM >>>
> >
> >I am testing an aprs email server...
> >The aprs spec only allows 0 - 67 characters in the 
> >message field which includes the email  address.
> 
> I would not object in this instance, since we know that
> the first part of the Email Message is an EMAIL address,
> and that part of the message, after being parsed out
> and used for addressing, is no longer part of the "message"
> content, therefore, that the next 67 bytes AFTER the email
> address may be retained.  
> 
> Thats a messed up wordy sentence to ssay that these
> might be the best rules for an Email ENgine:
> 
> 1) If APRS message is less than 67 then use as is.
> 2) If APRS message is longer than 67, then remove the
>     email address from the body and send what's left
> 3) If that is still more than 67 bytes, then truncate.
> 
> BUT wait....  hummh... at this point, the message is
> no longer on APRS anyway, but is in Email, so
> why do we need to truncate it at all?
> 
> de Wb4APR, Bob
> 

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