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.
