Re: X-* header fields

At 00:43 23/01/2004, Dave Crocker wrote:
> My own, primary concern about them is having an "experimental" header
> become a defacto standard and then having to find a way to get folks to
> use a new, non-X header name for it.  I believe that hasn't been
> successful yet, or at least not much.
I think it is arguable that you need some method of having 'experimental' 
headers 'in the wild'.
Getting rid of X- headers and saying 'you must come up with an agreed 
standard before you can add a new header of any sort' is going to inhibit 
innovation.
At least if you use X- headers, and they become defacto standards, then you 
can tell people off ;-)
One example I can think of of standards changing and people keeping up is 
with SMTP authentication. In the initial drafts of SMTP authentication the 
server would say 'AUTH=LOGIN'. In the final standard, the server says 'AUTH 
LOGIN'. Lots of people used the initial draft because authentication was 
needed so much, but then changed it to AUTH LOGIN (or supported both, in 
many cases) when the final standard came out.
I don't see a big problem with that. Yes, it would have been nice to get it 
right the first time, but if people hadn't been willing to risk getting it 
wrong and then having to put it right, we might never have ended up with an 
SMTP authentication standard!
If you look at other situations, eg the extra trace information that people 
are discussing in the SMTP groups, it's quite possible that someone will 
come up with a workable idea for this and then people may implement it, and 
later problems may be found, and the information will have to change.
If that's done, then either we'd have to use a header like 'Originator', 
and then risk total inoperability by changing the meaning of that header, 
or make 'OriginatorV2', 'OriginatorV3' etc when the changes happen, and not 
be able to use the nice 'Originator' ever again, because that's already 
been used.
Or, we could use 'X-Originator', then 'X-Originator2' etc, but then, when 
everyone's happy with the idea, we could use 'Originator', and deprecate 
the 'X-Originator' ones. Over time people would move to the Originator 
header (they may still READ the X-Originator ones, but wouldn't write them)
(This is just an example - yes, it would be nice to get it right first 
time, but that doesn't always happen cf SMTP authentication).

Paul                            VPOP3 - Internet Email Server/Gateway
support(_at_)pscs(_dot_)co(_dot_)uk                     http://www.pscs.co.uk/