[Standards-JIG] rfc3921bis, RC3

Ian Paterson ian.paterson at clientside.co.uk
Fri Oct 13 23:14:05 UTC 2006


Peter Saint-Andre wrote:
> Ian Paterson wrote:
>   
>> Peter Saint-Andre wrote:
>>     
>>> So, to summarize, I think for directed presence we send empty presence
>>> if the user is still online and empty unavailable presence if the user
>>> is now offline. Thus (using the rfc3921bis examples):
>>>
>>> <presence from='romeo at example.net/orchard'
>>>           to='shakespeare at chat.example.com'/>
>>>
>>> OR
>>>
>>> <presence from='romeo at example.net/orchard'
>>>           to='shakespeare at chat.example.com'
>>>           type='unavailable'/>
>>>       
>> That's good, just one other thing. Check out Joe's comment about the
>> need to include something like an <ignore/> element:
>>
>> Joe Hildebrand wrote on 2006/10/10:
>>     
>>> I'm not sure how you distinguish between the response to the probe and
>>> a client just sending an update, though.  I suppose in response to a
>>> probe by someone on the avails list, but not "both" or "from" in the
>>> roster, you respond with something like:
>>>
>>> <presence from='user at example.com/resource'
>>> to='room at conference.example.com'>
>>>   <ignore xmlns='http://xmpp.org/protocol/ignore'/>
>>> </presence>
>>>
>>> or something similar.
>>>
>>>       
>> That seems like a could solution to me.
>>     
>
> I'm not sure if the recipient cares *why* the user is unavailable, only
> *that* they are. I must be missing something...

Here we're talking about available presence, not unavailable. Without 
the <ignore/> it is possible to imagine scenarios where the server would 
not realise that an empty directed available presence stanza that it 
received is actually a response to one of the probes we are discussing. 
The server would then deliver the "directed available presence stanza" 
to the room, the room would broadcast it, and everyone's good presence 
data (show/status etc) would be overwritten with inaccurate data.

- Ian




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