[Standards] rfc3921bis: self-presence

Mridul Muralidharan mridul at sun.com
Wed Aug 29 21:55:17 UTC 2007


Peter Saint-Andre wrote:
> The old "xmppbis" page [1] had the following note:
> 
> ***
> 
> It is unnecessary, potentially confusing, and not recommended to add
> your own JID to your roster. However, RFC 3921 currently does not talk
> about how a server should handle such "self roster items" if they exist.
> The spec should probably specify that a server MUST NOT send presence
> probes to self roster items, since the server already knows that the
> entity is online once it receives initial presence from a specific
> resource. Thus a resource should never receive presence information
> about itself from its own server, although it will receive presence
> information about other available resources for that entity as currently
> specified in RFC 3921.
> 
> ***
> 
> This conflates two issues: (1) adding yourself to your roster and (2)
> receiving presence from your "self" resource.
> 
> IIRC we had list consensus that (1) is something we want to discourage.


2.3.2 talks specifically not allowing user to add his own bare jid to 
the roster (as a MUST).

> 
> But (2) seems OK. When you send presence to your server, your server
> delivers that presence to all of your available resources. Consider a
> user with two resources ("foo" and "bar") who then comes online with a
> third resource ("baz").
> 
> <presence from='user at example.com/baz'/>
> 
> [ ... to "foo" resource ... ]
> 
> <presence from='user at example.com/baz'
>           to='user at example.com'/>
> 
> [ ... to "bar" resource ... ]
> 
> <presence from='user at example.com/baz'
>           to='user at example.com'/>
> 
> [ ... to "baz" resource ... ]
> 
> <presence from='user at example.com/baz'
>           to='user at example.com'/>
> 


Why should an entity need to get its own presence ack'ed from the server 
? What is there a usecase for this ? Or is this a nice to have 
modification just to make things easier ?

There are way too many client and server deployments which already use 
the existing behavior - that is presence is not sent to the publisher, 
so we might want to weight against that when modifying this : since the 
bis spec compliant client should be able to interop with existing servers.





> Is it harmful for the "baz" resource to receive its self-presence? I
> don't see a particular reason why the server needs to avoid sending
> that. Would it confuse the client?
> 
> /psa


bis compliant clients will 'expect' this behavior - and so will break 
when they talk to older servers (assuming they do something with this 
presence status).
Reverse might also be the case - of existing clients breaking when they 
get presence for their own jid (will they treat it as conflict ?)

Regards,
Mridul



PS: I remember getting this clarified with Peter a while back - and he 
indicated that resource will not get its own presence ack'ed to it :)

> 
> [1] http://www.xmpp.org/xmppbis.html
> 
> 




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