[Standards-JIG] Client Capabilities (rant)

Mircea Bardac dev.list at mircea.bardac.net
Sun Nov 20 14:30:39 UTC 2005


On Sunday 20 November 2005 01:50, Chris Mullins wrote:
> 1 - Check presence and see if any JEP 115 capabilities are listed. If
> any of these are listed, we need to just ignore them, as they're client
> specific anyway and of no use to any other client. This JEP is of no use
> for general client capabilities and should be either renamed, or
> deprecated.

On Sunday 20 November 2005 12:12, Ian Paterson wrote:
> JEP-0115 was developed precisely to avoid this "packet storm on login".
> It's Requirements section includes, "Clients MUST be able to retrieve
> information without querying each user." In practice, it is rarely
> necessary to disco#info a client that advertises its capabilities via
> JEP-0115.


-- Quote (JEP-0115) --
This JEP makes several assumptions:

    * The type of client I am using is of interest to the people on my roster.
    * Different instances of the same client (including version) have the same 
base capabilities.
    * Members of a community tend to cluster around a small set of clients. 
More specifically, multiple people in my roster use the same client, and they 
upgrade versions relatively slowly (commonly a few times a year, perhaps once 
a week at most, certainly not once a minute).
    * Some clients are running against servers without server-to-server 
connectivity enabled, and without access to the Internet via HTTP.
-- end quote --

JEP-115 is not suited for *general* client capabilities discovery, since it is 
specifically mentions in the assumptions that CAPS could be used by clients 
of the same type.

There's absolutely no way of knowing wether, for example,
<presence>
  <c xmlns='http://jabber.org/protocol/caps'
     node='http://exodus.jabberstudio.org/caps'
     ver='0.9'
     ext='ftrans xhtmlim'/>
</presence>

<presence>
  <c xmlns='http://jabber.org/protocol/caps'
     node='http://psi-im.org/protocol/caps'
     ver='0.10'
     ext='filetransfer xhtml'/>
</presence>
mean the same thing.

As far as I understand, all features should (can) be discovered using Disco.
Some of these features (a subset of the above), should be discoverable using 
CAPS, right?

I believe that there should be a place specifying which already registered 
features (for Disco-ing) should also be available using CAPS, client 
independant. 


Mircea

-- 
http://mircea.bardac.net
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