remote client not updating redlights

John Shott shott at stanford.edu
Sat Jun 28 12:29:44 PDT 2008


Peter:

Hmmm. that's interesting and I haven't heard of others experiencing this 
problem ... but let me explain exactly what is supposed to be happening ...

In coral, clients are updated everytime someone enables or disables a 
tool, makes or deletes a reservation, reports (or clears) a problem or 
shutdown by messages that we call "events".  For the in-lab Coral 
clients (that is the clients that are automatically started when you are 
in the lab) each clients is registered to receive events and is notified 
any time any of these things happen.  Remote Coral, however, behaves a 
little bit differently ...because many Remote Clients are likely behind 
some sort of a firewall, if we sent them unsolicited events, they would 
likely get blocked by the firewall.  So each remote client sends in a 
message once every 5 minutes that says, in effect, "Send me any events 
that have been posted within the last few minutes ..."  While that means 
a remote client could be as much as 5 minutes out of date, in general 
that isn't a problem.  And, if you make a reservation on a remote 
client, you should see it immediately because the client "self-posts" 
it's own event.

I've just done some testing of my own remote client ... coupled with 
clearing a test shutdown from an in-lab client and confirmed that after 
a couple of minutes, by remote client showed the shutdown was cleared.

Now, we have seen that there are "heavily locked" down firewalls that 
won't allow a Remote Client to run at all .... for example at the NASA 
Ames Research Center .... but we haven't seen a firewall that will 
mostly run but would block requests for events, so I'm a bit confused as 
to what may be happening in your case.  I have no idea where 
128.12.142.202 is, but it would be interesting to see if this behavior 
occurs when you have remote coral connected from other locations .... or 
whether you are seeing something that we haven't seen before that may be 
local to that site.

Thanks,

John





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