8 Nov
2021
8 Nov
'21
4:16 p.m.
On 2021-11-08 15:57, Paul Koning wrote:
Absolutely agree. And I wonder if any software really do make use of the
OS codes in DAP. But it is nice that I can check what other systems
report from RSX. :-)
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
On Nov 7, 2021, at 6:40 PM, Thomas DeBellis
<tommytimesharing at gmail.com> wrote:
...
On the other hand, I don't remember my FAL/NFT/DAP blowing up on the wrong system,
either (they blow up on plenty of other stuff...) It would appear that there are two (2)
separate lists of system type bytes, one for NRT and the other for DAP, viz:
...
I don't know why DAP includes an OS type code at all. When I was working on DECnet
architecture I repeatedly argued that DAP implementations that do OS type checks are
broken, because they are assuming that they can correctly deduce the properties of some
remote system from its OS code. The correct way -- which is supported, in detail, by DAP
-- is to look at the feature flags to determine what the OS can and cannot do. And if
those flags are insufficient for a particular case, the solution is to extend the protocol
to add the missing information.
In other words, a client should conclude "the server can do X because it told me it
supports X" and not "the server can do X because it is running OS Y".