[Standards] Entity Capabilities Woes

Rachel Blackman rcb at ceruleanstudios.com
Thu Mar 15 07:36:23 UTC 2007

> Caps might be the hardest XEP to understand (it's not just i send you
> a question, you send me the answer), but it is the simplest and most
> flexible solution we have for those requirements. I haven't yet heard
> any other proposal that meets them, I don't see how it could be done
> better, and I never complained about it while I implemented the XEP
> (something I did with a lot of other XEPs, that *really* were overly
> complicated).

Caps COULD definitely use a brief, easy-to-understand best-practices  
guide to implementation, because people do some weird stuff.  Gizmo  
Project's client has the most frighteningly busted caps  
implementation I've ever seen, for instance: it sends the entire  
client name and version as the 'ver' field, and all the disco  
responses to the node/ver/ext combinations return empty disco results.

As a result, I had to special-case that if I get an empty disco  
result for a capsnode#ver query, I need to do a node-less disco query  
to find the features instead.  Similarly, I've seen people disagree  
on when/how-often to send the caps field embedded in a message (I  
send it on the first message to a given contact, and then never  
again), and so on.

A simple 'how to do this well' might help clear some of that up. :)

Rachel Blackman <rcb at ceruleanstudios.com>
Trillian Messenger - http://www.trillianastra.com/

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