[Standards-JIG] Re: Dead participants in MU-conf, JEP-0045

Heiner Wolf wolf at bluehands.de
Tue Jan 18 18:44:17 UTC 2005


>I don't understand your question. Let's say we have three people in a 
>room: Alice, Bob, and Carol. Carol goes offline ungracefully (trips
over 
>the network cable or whatever) but she doesn't send unavailable
presence 
>to the room or to her server, and her server doesn't detect that she 
>went offline for 5 minutes. So for those 5 minutes it still appears
that 
>Carol is in the room (until her server figures out that she is offline 
>and sends unavailable presence to the room, per RFC 3921). 

Yes, only that the 5 minutes can be weeks in the real world. Don't ask
me what happens. The only thing I know is that there are conditions
where clients go offline and participants stay in rooms for a very long
time. 

My showcase is this room:
com.7191e2296b14bc17f30c7e0be0704fc3498e21aa at atlas.jabber.org. There is
someone called "Der Einsame der Zeit". This was my test account. I don't
know how I managed to create such a persistant user. I was testing
amessage.info as default c2s server when jabber.org was slow. Worked
well only, amessage.info sometimes does not deliver
presence-unavailable. Therefore I had to use another default server. But
the zombie remained from my testing. 

If you enter the room you get:
<presence
from='com.7191e2296b14bc17f30c7e0be0704fc3498e21aa at atlas.jabber.org/Der
Einsame der Zeit'>
  <x xmlns='jabber:x:delay' stamp='20041102T11:41:52' 
 
from='com.7191e2296b14bc17f30c7e0be0704fc3498e21aa at atlas.jabber.org/Der
Einsame der Zeit'/>
</presence>

stamp='20041102T11:41:52' is a very long time. 
Obviously atlas.jabber.org has not been rebooted since Nov. 2, 2004. 

>Now, if 
>Carol's server is smarter, it may detect that she is offline sooner 
>(e.g., when it tries to deliver messages to her that are sent in the 
>room). So if Alice and Bob are chatting in the room and messages from 
>the room result in errors, then the room should remove Carol. I think 

What if Carol's server detects the disconnect, but does not forward the
presence-unavailable to the room? 

>what is confusing me about your question is the term "message-chat"...

Sorry, was an abbreviation of <message type='chat' />

>> Does this mean that any message-chat in the room should remove the
user,
>> if the user went offline without his server telling the room?

What I mean is: "A MUC service SHOULD remove a user if the service
receives a delivery-related error"
Any chat in the room will be forwarded to the user's server. If the
user's server is not reachable or if it finds the client offline, does
this <message type='chat'/> generate such a "delivery-related error"? If
it does, then any chat in the room should remove the zombie. But it does
not. So where is the problem? Either the <message type='chat'/> to the
user's server does not generate a "delivery-related error" or the MUC
ignores it. If it's MUC's fault then we can fix it. If the server does
not issue a "delivery-related error" then someone should fix the server
and MUC should protect itself from such a "bad behaviour". 

hw
--
Dr. Klaus H. Wolf
bluehands GmbH & Co.mmunication KG
http://www.bluehands.de/people/hw
+49 (0721) 16108 75
--
Jabber enabled Virtual Presence on the Web: http://www.lluna.de/
Open Source Future History: http://www.galactic-developments.com/



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