[Standards-JIG] The Ack Hack.

Michal vorner Vaner michal.vaner at kdemail.net
Thu May 11 15:37:40 UTC 2006


On Thu, May 11, 2006 at 11:42:25PM +1000, Trejkaz wrote:
> On Thursday 11 May 2006 16:56, Michal vorner Vaner wrote:
> > But, this has a significant problem. There are many clients that has no
> > way of remembering these numbers between sessions. It can as well be my
> > computer goes down and it does not save the number to its disk.
> 
> A client which can't be bothered saving state might as well not care about 
> this feature, as implementing the rest of it is bound to be harder than 
> writing a few bytes to a file.

Not all clients are on computers. Not all clients have the right to save
anything. There are web clients, flash clients, clients on friends
computer, where it is not feasible to save anything at all. I do not
speak about complexity, but about the fact that not all environments are
PC with nice big disk.

> > It may be that the power is off unexpectadly and I use my mobile phone
> > client, which did not have the last conversation.
> 
> However yes, for the situation where you join from a completely different 
> client, the server will simply have to assume that every message since the 
> last ack is undelivered, and deliver them all again.
> 
> What I wonder about all this is the following: if I have two clients logged 
> in, and the server spools 100 messages during the time between one client 
> having connection troubles and the connection finally closing, what happens?  
> Do all those messages wait the couple of seconds for the client to come back, 
> or do they just all spew to the second client immediately?
> 

Well, I would act as if the client disconnected before the connection
problems, which would mean giving them to the second connection.
However, it does not allow doing this with full JID addressed stanzas.
They would need to be taken care just as they came after this
disconnecting.

-- 

Work with computer has 2 phases. First, computer waits for the user to tell it what to do, then the user waits for the computer to do it.
Therefore, computer work consists mostly of waiting.

Michal "vorner" Vaner
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