[Standards-JIG] Semantics of negative priority

Stephen Marquard scm at marquard.net
Thu Jan 13 07:36:18 UTC 2005


I have a question about how servers should handle resources with 
negative priority. According to my interpretation of XMPP-IM:

(a) A resource with negative priority is not eligible to receive 
messages directed to the bare jid (user at domain) (XMPP-IM

(b) Negative resources should receive presence stanzas:

"For presence stanzas other than those of type "probe", the server MUST 
deliver the stanza to all available resources; for presence probes, the 
server SHOULD reply based on the rules defined in Presence 
ProbesPresence Probes." (XMPP-IM

(c) The server should respond to presence probes on behalf of negative 

"Else, if the contact has at least one available resource, the server 
MUST reply to the presence probe by sending to the user the full XML of 
the last presence stanza with no 'to' attribute received by the server 
from each of the contact's available resources (again, subject to 
privacy lists in force for each session)." (XMPP-IM

(a) seems straightforward, but is my interpretation of (b) and (c) 
correct, i.e. a resource with negative priority is considered an 
"available" resource for presence purposes ?

What are negative priorities typically used for ?


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