As designated reviewer for registrations, here's my current position:
If this were a mail header, I think the response would be fairly
clear-cut: the email standards prohibit the standardization of headers
named X-whatever. But this is HTTP, and the last time I checked I
didn't see any specific status for X-headers there. And there is a
general feeling that, while it sometimes serves a purpose, the approach
of using X-headers for experimentation generally does not work, for
reasons that are exemplified by this debate.
This leaves us with the strong expectations of developers who have
worked with IETF protocols that X-headers are experimental, and not to
be taken seriously.
The header registration procedure itself deliberately does not take a
position on X- headers, so there is nothing there specifically
prohibiting the permanent registration of X-headers - it's up to the
protocol concerned (HTTP in this case) to specify what is the minimum
requirement for standardization. Permanent registration requires
publication as "open standard", which means a clear community consensus
is required; this is not necessarily an IETF standard - W3C REC is good
- but I'd expect some dialog with the IETF if there appears to be a
conflict of styles or expectations.
Thus: if the document is approved as an IETF proposed standard with the
X-header specifications (which I think may be effectively required for
all but new HTTP entity-header fields), then I would have no problem
agreeing to the permanent registration of the X-headers. Otherwise, I
would look for IETF review and consensus by IESG and/or HTTP protocol
experts that permanent registration of an X-header is not likely to
cause any problems in other areas.
Personally, if I have to make the call, I'd allow it because I can't see
any fundamental reason not to do so. But I really would prefer to see
wider review.
None of this in any way impedes provisional registration.
#g
--
SM wrote:
Hi Francois,
At 00:57 13-08-2009, Francois Daoust wrote:
I'm not sure I understand why you directly jump to deprecated at this
step.
A provisional registration is a step towards permanent registration.
Omitting the depreciated status would be an encouragement to adopt
that header field name. Once that is done, it will be argued that the
"X-" cannot be dropped.
In future, someone will come up with an argument that there is already
some "X-" header names in the permanent registry.
I thought the purpose of the provisional registry was to reserve
names while the underlying specification matures along the
standard-track. The underlying specification is not definitive, and
there will be at least one other Last Call working draft period
during which the working group expects to receive external comments
both on the choice of names and the usefulness of these HTTP header
fields.
Yes. But if the working group is not agreeing on the change now, it
is improbable that they will agree to it on another Last Call.
The use of the "X-" prefix has been extensively discussed both
formally within the group and informally with some IETF contributors.
The fact that companies use private "X-" header field names on a
public level is a pity, but it is unfortunately common practice
within mobile networks. We are trying to move away from a situation
where there exist 5 different sets of "X-" header field names to a
situation where there's only one. Mobile content developers complain
about the existence of these different sets that were imposed on
them. They do not want to hear about a new one, introduced for the
sake of removing the "X-" prefix, in particular if that means they
would still have to be prepared to receive the "X-" form and the non
"X-" during the transition period.
The transition period can be now or later. The longer we wait to do
such changes, the more difficult it will be.
That is the reason why the mobile web best practices working group
thinks it is reasonable to bend the naming rule here. We are not
aware of any real difference between "X-" header fields and regular
non "X-" ones, apart from their intended use.
When using "X-" headers, it is difficult to tell whether anyone
outside the working group is using the headers for other purposes.
Regards,
-sm
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