Re: How to refresh cached image ONCE

Jorge wrote:
"C. (http://symcbean.blogspot.com/)" wrote:
However, I think it may be possible to do for the client who just
uploaded the data - since, if they click the 'Refresh' button in the
browser it carries out an unconditional reload of the content. I'm
wanting to emulate this from Javascript.

See here : http://tinyurl.com/6lwmmb

I explained to you before why those alias URLs are unsuitable and
unnecessary in Usenet, and asked you to stop posting them.

I am asking you again to post original URL(s) here instead. As a Google
Groups user who heavily relies on the information in that archive, surely
you can see the advantages in complying with that request.

[...]
But still, in order to trigger the reload, it's unclear to me how is
it going to be discovered client-side, that the image content has
changed at the server-side ?

Then you should read <http://mnot.net/cache-docs> (again). It explains in
great detail which headers are used by clients to determine that.

Therefore, I see two distinct possibilities and two variations:

1. A client that makes only GET requests.

A) If there is a cached resource and headers indicate that the
server-side resource has not changed, it disconnects without
receiving the message body and retrieves the resource from
the cache instead.

B) The entire response is evaluated regardless of headers first.
Then headers are evaluated to determine which resource can be
considered newer. Then proceed as in (A).

2. A client that makes a HEAD request first. If headers indicate that
the cached resource (if there is one) and the server-side resource
differ, it proceeds with a GET request; else it retrieves the
resource from the cache. (Further tests may happen afterwards.)


HTH

PointedEars
--
Anyone who slaps a 'this page is best viewed with Browser X' label on
a Web page appears to be yearning for the bad old days, before the Web,
when you had very little chance of reading a document written on another
computer, another word processor, or another network. -- Tim Berners-Lee
.

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