proposal for capabilities lookup

[Dag Arneson]

Martin Atkins wrote:
> I think two goals are most important for adoption:
> * Those using their own site as an identity URL must be able to add
> YADIS support without writing any code or greatly disturbing their
> existing site. (The HTML indirection case.) This implies a regular GET,
> as you mentioned.
> * In *that same request* consumers must somehow indicate that it's
> really capabilities that they are interested in, so that larger identity
> hosts like LiveJournal can remove the layer of indirection and just
> return the capabilities directly, without having to generate a rather
> costly journal page that's just going to be discarded. This is the
> purpose I was bending "Accept" for.

It seems like if we want to fulfill this goal as well as minimizing 
bandwidth, we're going to have to have 2 methods of retrieving the data, 
one efficient one that may require some new code, ala Dan Libby's 
OPTIONS request idea, and one less efficient fallback mode that is 
simple to implement, like the link rel tag that OpenID uses.  Then 
people can get up and running with YADIS quickly, but those who wish to 
put a little more effort in can save on bandwidth.