[Nut-upsdev] MGE NMC and NutShutdownModule (and other stuff)

[Arjen de Korte]

Citeren Marco Chiappero <marco op absence.it>:

> Ok, I clearly see your point now, the NSM would not follow this  
> design rule, however it could be an acceptable solution, requiring  
> not much code and no modification at all to the current structure.

It's not a design rule, its how the socket protocol works. One  
connection, one driver, one UPS (outlet). This is the base of the  
system and *any* changes there have impact on *all* systems (not only  
the netxml-ups driver). At the moment we have bigger things to work on.

> Sure, but a single driver could contain all the (vendor) specific  
> logic without tainting the upsd code (starting from a netxml-ups  
> clone and my patch).

Your proposed changes to the netxml-ups driver can only monitor a  
single UPS for the above mentioned reason. The socket protocol between  
driver and server can only handle one UPS, not multiple ones (which  
would be essential to even consider including). The problem with the  
NSM stuff is, that this requires exclusive access to a socket on the  
machine the driver (and as a consequence, the server) is running on.  
This is a problem and I really see no easy solution to that.

> On the other side I think that, discarding the separated driver  
> solution, it could still sound reasonable to provide a NSM in the  
> mge-xml subdriver for the moment, even though currently it is useful  
> on small setups only. Isn't it?

Not in the netxml-ups (or mge-xml subdriver). Given the above  
difficulties, this *must* be a separate driver, because we already  
have production systems that would break if this was added. I would  
consider a NSM driver only, but without the parsing of additional XML  
data from the UPS. It should only parse the ALARM messages, nothing  
more. For logging purposes, one would then have to run a SNMP or XML  
enabled driver on the side and use the NSM one to shutdown attached  
clients.

Best regards, Arjen
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