Re: [ogpx] Protocol negotiation and evolution

[Infinity Linden <[e-mail]>]

whoops. sent this to carlo, but forgot to send this to the list.


the current technique for "feature negotiation" is part of service
establishment. the way it works now is that after authentication or
authorization the service returns a seed capability to the client, and
the client requests named capabilities from the service. if a client
doesn't know how to utilize a particular service, it doesn't request
it. if the service doesn't know how to provide a requested service, it
doesn't return a capability for it. if there are multiple,
incompatible versions of the service, each version gets it's own
distinct capability name.

additionally, to reduce the effect of version skew, we use the
technique described in the MMOX list at
http://www.ietf.org/mail-archive/web/mmox/current/msg00679.html .

for content negotiation for protocol messages carried over HTTP, we
use the HTTP semantics: the client identifies the content type if the
request with the Content-Type: header on the request. if the client
needs a particular content type, it uses the  Accept: header to
identify acceptable content types. And the server uses the
Content-Type: header on the response to identify the content type of
the response. if the server cannot generate a response of the media
type requested, it will send a 415  response.

but more options is always better, so to support situations where the
previous technique doesn't work or isn't appropriate or just to give
options, consider documenting it as a draft, then later we can have
the discussion about integrating it into other drafts or releasing it
as it's own draft.

-cheers
-meadhbh