On 6/24/21 3:48 PM, Roger Price wrote:
During the ISE review of the proposed RFC, the IETF editor has asked
for clarification of the LOGIN command, since he, like most people,
assumes that "LOGIN" means something like "login to a shell".
The Developer Guide Chapter 9
https://networkupstools.org/docs/developer-guide.chunked/ar01s09.html
"Network Protocol Information" says
9.9. LOGIN
LOGIN <upsname> Response: OK (upon success) or various errors
Note This requires "upsmon slave" or "upsmon master" in upsd.users
Use this to log the fact that a system is drawing power from this
UPS. The
upsmon master will wait until the count of attached systems reaches 1
- itself.
This allows the slaves to shut down first.
Note You probably shouldn’t send this command unless you are upsmon,
or a
upsmon replacement.
9.4 GET NUMLOGINS <upsname>
Response: NUMLOGINS <UPSNAME> <VALUE>
where <value> is the number of clients which have done LOGIN for this
UPS. This
is used by the master upsmon to determine how many clients are still
connected
when starting the shutdown process.
I propose saying:
Figure 4 "The client"
,--------------------,---------------------,
,-----, | UPS <-Commands Primary |
| |---| Attachment | Management | Primary
| |===| Daemon Responses-> Daemon |
| | '--------------------'---------------------'
| UPS | ^
| | '<-Commands---Responses->,
| | v
| | ,--------------,-----------------,
| |============| | Secondary |
/-----\ | | Management | Secondary
| | Daemon |
'--------------'-----------------'
LOGIN is not the conventional user access to a shell. In a
configuration such as Figure 4 in which a UPS protects more than one
system, the Primary (2.8) Management Daemon (2.6), upsmon, needs to
know how many Secondaries (2.9) are currently "active", i.e. powered
by the UPS, either on wall or battery power. The Attachment Daemon
(2.1), upsd, supports this by keeping a count of all the "active"
systems powered by a UPS. The count is initialised, one secondary at a
time by the LOGIN command, which should be understood as "count this
secondary as active". LOGIN is one of a trio of commands for Secondary
(2.9) counting: command LOGOUT (4.2.7) decrements the count and a
Management Daemon (2.6), upsmon, may read the count at any time using
command NUMLOGINS (4.2.2.3).
The LOGIN command is also sent to the Attachment Daemon (2.1), upsd,
for the Primary (2.8) so during normal, fully protected operation, the
count is 1 (the Primary (2.8)) + the number of Secondaries (2.9).
During a full system shutdown, the count drops as each Secondary (2.9)
Management Daemon (2.6), upsmon, executes command LOGOUT (4.2.7)
during its own shutdown. When the count drops to 1, only the Primary
(2.8) is "active" and it knows that all the Secondaries (2.9) have
shut down.
Is that correct?
I did not look at the code but based on my experience with the
application, your proposal sounds very good to me.
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