[Zope] Fixing refresh problems

[Brian Lloyd]

> What seems evident is that newer browsers such as IE 5.0 do not heed
> Pragma and Expires headers correctly. The solution is to provide the
> Cache-Control header, which supersedes the "Pragma: no-cache" 
> header in
> HTTP 1.1, thus:
...
> What bugs me is that ZServer doesn't handle If-Modified-Since 
> correctly,
> or doesn't seem to. Telnetting to ZServer and typing a future 
> date value
> doesn't elicit the expected 304 error ("Not modified"). 

I tried putting handling in for this recently, with pretty
bad results... a number of browsers seemed to have problems
with 304's implemented, so I took them back out. I could,
of course, have been doing something stupid that caused the
odd (hanging) behavior in some clients, so if anyone wants
to implement If-Modified-Since handling, I'd be happy to roll
it in if it is thoroughly tested and found not to cause any
problems with any known clients...

> Also, for me,
> ZServer returns a Last-Modified timestamp that is an hour off. The
> DateTime module seems to be slightly brain damaged in its handling of
> time zones; if a document was modified at 18:00 GMT+1 (which 
> is my time
> zone), ZServer will emit:
> 
>   Last-Modified: Mon, 21 Jun 1999 16:00:00 GMT
> 
> I've never been a wizard with date arithmetic, but this looks weird to
> me: When my local time is 18:00, this is 17:00 GMT time. Is 
> this perhaps
> related to the timezone bug that Dylan Jay posted a fix for a while
> back?

No, this probably reflects daylight savings time not being
handled correctly... which is unforunately a *hard* problem
(with a capital H :). The DT module tries to deal with this
as best it can, but zones for which there is no information
in it's pre-fab database are probably mishandled during DST.

Do you happen to know if mxDateTime or any of the other date/
time handling packages out there handle DST in arbitrary 
timezones? Perhaps there is something we could learn from one
of those...


Brian Lloyd        brian@digicool.com
Software Engineer  540.371.6909              
Digital Creations  http://www.digicool.com