Hi Terry,
> For some reason the site seems to reload from history, even when the
> reload button is pressed. I had to use 'Clear recent history' in the
> Preferences to force a proper reload. Can anyone see why?
Yes, HTTP lets clients and servers converse over whether they need to
fetch a new version of the page to save on needless transfers. A server
can use it to help stop the `reload addicts' that keep reloading,
waiting for the count to go up by one. :-)
Here's the conversation for the first time it's fetched, some headers
deleted. A paragraph of request, another of reply.
GET /Digital-Economy/ HTTP/1.0
Host: petitions.number10.gov.uk
Pragma: no-cache
Cache-Control: no-cache, max-age=259200
HTTP/1.0 200 OK
Date: Sat, 20 Mar 2010 13:12:05 GMT
Expires: Sat, 20 Mar 2010 13:12:06 GMT
Content-Length: 16664
Last-Modified: Sat, 20 Mar 2010 11:31:03 GMT
Cache-Control: max-age=1
The next time the browser asks, including on a reload, it adds the
`If-Modified-Since' header.
GET /Digital-Economy/ HTTP/1.0
If-Modified-Since: Sat, 20 Mar 2010 11:31:03 GMT
Host: petitions.number10.gov.uk
Cache-Control: max-age=259200
HTTP/1.0 304 Not Modified
Date: Sat, 20 Mar 2010 13:11:54 GMT
Hold down Shift in most browsers when clicking the Reload icon to make
it not do this and really get a fresh version of the page. But use
sparingly. There's a reason it works as above. You don't want the
server so heavily loaded that folks don't bother signing. :-)
Cheers,
Ralph.
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