[standards-jig] Disco features caching

Jacek Konieczny jajcus at bnet.pl
Wed May 21 07:26:19 UTC 2003

When service discovery is widely used it could generate a lot of trafic.
Many interactions with Jabber entity would require some capabilities of
the entity to be discovered first. Each disco request will result in
a reply with all supported namespaces and featurese - this usually will
be quite a long list. 

After sending the initial presence client could get disco queries from
most online users in his roster (other clients may want to get list of
features supported by remote user, to show local user what services are
available). This would be fatal for mobile clients.

That is why some kind of disco reply caching should be implemented on
server. It could be just caching of last client reply - but this will
not work well if the feature list changes during a session. Other
solution would be publishing the list to the server (similary to what
can be done with disco items). The list on the server should be
maintained for one resource and one session - I don't think persistent
storage of this information is needed.


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