xml-dev - RE: Re: Prevent caching.

[paulo.gaspar@krankikom.de]

<resources> 
A used a great document on how caches work on: 
http://www.netapp.com/products/netcache/cache_basics.html 
(Yes, it is a commercial site.) 
 
Another VERY interesting one, with implementation examples 
for many languages/environments (including ASPs and PHP) at:

http://www.mnot.net/cache_docs/ 
 
And THE web caching site (which also includes a version of 
the previous article) at: 
http://www.web-caching.com/ 
</resources> 
 
 
<method> 
Tunning the time to expire of a document (using the HTTP 
headers) can also allow you to establish a good compromise 
between performance and evolutionary needs. 
 
What do I mean by that? Well, doing something like: 
- No cache when you are developing the site with no users; 
- Some minutes to expire while evolution is still going 
on and you already have some users; 
- An hour or so with already many users but not so many 
fixes; 
- and so on until the time to expire matches the time to 
the publication of new versions of the content. 
</method> 
 

Have fun,

Paulo
 
--- Original Message ---
Rick JELLIFFE <ricko@geotempo.com> Wrote on 
Mon, 05 Jun 2000 18:09:24 +0800
 ------------------ 
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




-----
Sent using MailStart.com ( http://MailStart.Com/welcome.html )
The FREE way to access your mailbox via any web browser, anywhere!


***************************************************************************
This is xml-dev, the mailing list for XML developers.
To unsubscribe, mailto:majordomo@xml.org&BODY=unsubscribe%20xml-dev
List archives are available at http://xml.org/archives/xml-dev/
***************************************************************************