[Web-SIG] PEP 444 (aka Web3)

[Chris McDonough]

On Fri, 2010-09-17 at 14:14 -0400, Ian Bicking wrote:

> OK, so maybe it should just be clarified:
> 
> * Middleware and servers should not modify or add Content-Length,
> Date, or other headers unless they have reason to do so, and they must
> ensure that the response is valid (e.g., there should never be two
> Content-Length headers).

I tried adding such a statement to a local copy of the specification,
but I wasn't able to really "nail" it.  If someone here can come up with
some unambiguous wording (defining "unless they have reason to do so"
and "other headers" above would be a good start), I'd just put it in.

> It still seems reasonable that *if* there is no Content-Length, and
> the server can guess easily enough (mostly it is returned an actual
> list/tuple that we know can be introspected fast and without side
> effects), then it's perfectly reasonable to set it -- but certainly
> the server doesn't "own" that header (or any other, except maybe some
> connection-related headers?).

I'm -0 on the server trying to guess the Content-Length header.  It just
doesn't seem like much of a burden to place on an application and it's
easier to specify that an application must do this than it is to specify
how a server should behave in the face of a missing Content-Length.  I
also believe Graham has argued against making the server guess, I
presume this causes him some pain somehow (probably underspecification
in WSGI).

- C