----- Original Message -----
From: "Yoryos" <[EMAIL PROTECTED]>
To: "Tomcat Users List" <users@tomcat.apache.org>
Sent: Wednesday, September 03, 2008 8:57 PM
Subject: Re: Etags vs Week Etags
On Wed, Sep 3, 2008 at 8:12 PM, Johnny Kewl <[EMAIL PROTECTED]> wrote:
Flipping good question... and I have a feeling that there is some
philosophy in the answer... reasons for the way it done...
The short answer is that you cant (I think)... the default servlet makes
em
weak (thats the philamamasomamy)...
That first section (strong) does nothing... the reason is that the
setEtag
method is there but as far as i can tell, never ever called by anything
in
Tomcat.
Its a hook...
But stay calm... there are ways...
This clever guy did this...
http://blog.bcarlso.net/articles/2007/10/19/tomcat-weak-etags-and-javascript-css-caching
He is basically overriding the default servlet stuff to get things
done....
its smart, he knows his tomcat, but personally I dont like it...
I think the generic problem is that a static resource cant control its
Etag... its a dumb image, and secondly no matter what a web server does,
another web server is going to do it different, so strong loses its
meaning
(more philamamasomamy)... or more simply, you just got to do it
yourself...
I would prefer (or try, I havnt giving this a go)... make a little
servlet,
set the Etag headers yourself, map it to all the static resources you
want
to control...
And then do what you have to
getContentLength() + "-" + getLastModified() + IncludeFiles() +
IncludedImages() + WhateEver() "\"";
etc... I think thats easiest...
The philamamasomamy on why TC chose to make it weak would be interesting
to
hear, but I do think that any serious scheme... on its way to some kind
of
private RSS system... will be doing its own thing.
Have fun... nice question
Well a quick solution is to extend the DefaultServlet to apply a "good"
etag. But then I should also check for this etag in case I have a request
with headers If-None-Match. This means that I should also extend the
org.apache.naming.resources.ResourceAttributes
class in order to be giving me a "good" etag.
I don't really care about the philosophy of using week etags. I'm sure
there
is one but as I can see there isn't any easy way of letting the user
decide
the default headers of static content except from reinventing the wheel
(creating a custom DefaultServlet) and I think this is a problem as the
implementation of a new DefaultServlet isn't as easy as it seems to be.
I would try front end servlet, or a filter before massaging default
servlet...
but I agree, there is a lot of functionality in that deafult servlet that
could be brought out...
As options and as extended tools in normal servlets.
Probably has a lot to do with following Suns specs to the letter, which is a
good thing I guess.
For example if you want XSLT in tomcat, first impression is its xerces and a
complex servlet and lots of pain... you actually think tomcat cant do it,
but then you look at the default servlet and "Obama!" its there ;) I call it
TC's hidden gold mine ;)
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