[Standards] Re: [jdev] XEP-0115: Entity Capabilities

Jacek Konieczny jajcus at jajcus.net
Wed Jun 27 08:32:55 UTC 2007

On Tue, Jun 26, 2007 at 11:59:24PM -0700, Rachel Blackman wrote:
> But second, and more importantly, not one single person has offered a  
> solution other than 'make every extension hardcoded' or 'just probe  
> each contact, cache only per-JID,' which returns us to the original  
> troublesome network-flooding behavior on logins.

That is not true. Years ago I have proposed other solution: instead of
announcing client name version and caps clients should announce digest
(e.g. MD5 or SHA) of normalized set of supported features. The list
would have to be obtained only once per feature set and it could be
verified. The traffic would not be much bigger than with current
solution and the 'cache taint' problem would be gone. And
implementations could be simpler (no need for capability registry --
namespace registry is enough) and less error-prone (when a new namespace
is added the digest would change 'automatically'. Currently developers
have to manually update version or capability string).

I think the digest could be used with current specification too -- as
the only capability string, bound with all the supported namespaces. But
XEP-0115 is not optimized for such usage and says nothing about digest


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