[Standards-JIG] Re: What happened to the ACK proposal?

Justin Karneges justin-keyword-jabber.093179 at affinix.com
Thu Aug 18 00:51:59 UTC 2005


On Wednesday 17 August 2005 01:07 pm, Peter Saint-Andre wrote:
> Jacek Konieczny wrote:
> > Jabber could be much more reliable now if Jabber Council accepted the
> > JEP instead of trying to be politically-correct and leaving that for
> > IETF.
>
> Based on the message from Tomasz Sterna, it sounds as if the Jabber
> network would be much more reliable if everyone deployed WPJabber. :)
>
> http://mail.jabber.org/pipermail/standards-jig/2005-August/008295.html
>
> So is this a protocol issue or an implementation issue?

This is a clever trick, however it makes some assumptions:

 1) The recipient must send data to acknowledge a stanza.  Since it does this 
unknowingly, this may not happen for a very long time.  This means there is a 
potentially large window where a successfully received stanza is considered 
undelivered.

 2) There is no context between the stanza sent and the data from the 
recipient.  This makes it possible for a race condition to occur, whereby 
both parties send data simultaneously, and the sender immediately considers 
his sent stanza to be acknowledged when it may not have been.

In practice, this trick probably works alright, since most clients and servers 
send whitespace keep-alives and the chance of #2 happening is small.  Even 
so, it is still a protocol issue.  No matter how clever the implementation 
is, this issue won't be properly solved without some coordination from both 
sides of the stream.

-Justin



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