xml-dev - Re: Prevent caching.

[Rick JELLIFFE <ricko@geotempo.com>]

Johan Warman wrote:
> 
> Hi
> 
> I've wrote some dll's that generates xml-documents. My problem is that when
> I create a new doc with same name as an old one, the old one is cached and I
> have to reload the doc manually. Does anybody have a clue how to avoid this.
> I'm using IIS4, MS IExplorer 5.0, ASP and XSL.
 
Caching effects are complete nightmares, especially during debugging.

Here are the places that you need to look at

1) the HTTP headers
2) meta tags in any HTML
3) the cache or history files in your browser
4) caching in your proxy server  (if your proxy server administrator
cannot/will not turn off caching in proxy server, turn off proxy use in
your browser when you are debugging, even though it costs you temporary
access through your firewall.)

The basic rule for development is to turn off caching everywhere, to
generate HTTP headers (or HTML headers) which block caching, to try to
generate unique names for files whereever possible, and to close browser
applications regularly (sometimes you may have to clear the history
before quitting. (For some browsers, you may even find that there is a
behaviour difference between reloading with the reload button, the
reload+escape button, and using the buttons back then forwards.)

I don't know about DLLs, but it is important to realize that different
parts of the a compound document may be reloaded at different times. 

If you are using Java Servlets (you are not, but this is the best I can
do, you will have to look up the equivalents in your API) then you to
set the HTTP headers correctly you call
  response.setHeader("Pragme","No-cache");
  resonse.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires",0);
These can well be standard part of debugging: your sections QC policy
should mandate these and someone should look through code to make sure
that it is there. 

Here, we send around an email telling explaining to everyone who needs
to trial some software under development to turn off their browser
caching, too.  Hope this is some help.

Rick Jelliffe

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