[HECnet] PSTHRU.EXE poor-man routing object 123 for VMS on VAX

[Thomas DeBellis]

Your mention of PHONE rung a bell.  Err...  Jogged a memory.

Tops-20 implements the VAX PHONE protocol (object 29).  The source code 
includes a separate file called 'DNCONN', which is a generalized 
implementation of PMR, meaning it can be linked with other modules.  As 
an aside, another pleasant memory was that I recognized the author, 
Larry Campbell, from my Marlboro days.

The Tops-20 mail system implements just about any kind of routing you 
can think of, MAIL-11, SMTP, BITNET and that odd Unix 'bang' notation.  
It's odd for Tops-20 people because ! is a comment character for COMND%.

Version 4 and 5 Tops-20 implemented NRT connection handling and user 
space.  Both the NRT server and client did PMR, but predate DNCONN, so 
they don't use it.  For better execution, speed, the NRT server was 
moved into the monitor, but I believe the connections were still handled 
in user space.  By version 6, the connection logic was moved into the 
monitor as well as the client logic.

The way the client logic worked is interesting; you'd make a connection 
and then issue an MTOPR% and the monitor would take control of the 
terminal, doing all the character handling in monitor mode, which 
eliminated a lot of context switching and (presumably) yielded better 
cache performance.  At Columbia, we realized that this effectively made 
SETHOST redundant and put the parsing code into the EXEC, thus saving us 
a fork slot.

The only downside was that you could no longer link a DECnet connection 
to an NRT in user mode, which eliminated DNCONN and broke certain kinds 
of solutions.  It's on my list to put it back.


I don't recall about the Tops-20 CTERM client.
> ------------------------------------------------------------------------
> On 12/28/21 10:34 AM, G. wrote:
>
> Paul Koning explained it way better than I could do. In VMS both PHONE 
> and SET HOST, when presented with a PMR address, establish a 
> pass-through connection via intermediate nodes thanks to object 123 
> and its related PSTHRU.EXE helper.
>
> Not by chance both PHONE.EXE and RTPAD.EXE call some UNS$NET_CONNECT 
> routine, where UNS obviously stands for unsupported.  Other tools or 
> functions such as MAIL and RMS use their own mechanisms to do the same.
>
> I agree with you about repositories, hence I'm trying to spread 
> PSTHRU.EXE around to avoid losing it again :)
>
> HTH,
> G.
>> ------------------------------------------------------------------------
>> On Sun, 26 Dec 2021 18:04:24 -0500, Thomas DeBellis wrote:
>>
>> Could you elaborate on what 'poor man' routing means, just so I'm 
>> sure I have  the correct context?  I know that this term existed for 
>> 20's route NRT sessions.  It doesn't exist for CTERM.  I don't 
>> /think/ I remember seeing it for DAP/FAL/NFT. 
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