[Standards] presence TTL

Justin Karneges justin at affinix.com
Tue Jul 16 05:31:10 UTC 2013

Hey folks,

For awhile I've been designing systems whereby any entity announcing 
presence has the responsibility of continuously refreshing this 
presence. I've even done this within XMPP by including a <ttl> element 
in the presence stanza indicating a timeout value. If the receiving 
entity does not receive a new presence stanza within this time period 
then it considers the sending entity to be unavailable. I prefer this to 
the practice of the receiving entity having to periodically probe 
whoever it has received presence from. The end result is pretty much the 
same, but to me it feels cleaner to put this responsibility on the sender.

I wonder if it couldn't hurt to standardize a simple thing like this?

<presence from="alice" to="bob">
   <status>I'm here</status>
   <ttl xmlns="urn:xmpp:tmp:ttl">600</ttl>

Given the above directed presence, Bob would expect another presence 
stanza from Alice within 10 minutes.


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