A heads up

Something not covered in the manual (and not discussed yet on this list 
as far as I can see) is the effect of keep-alives on TUX.  Don't get me 
wrong, TUX handles them beautifully;  However, I found myself debugging 
a seemingly impossible bug -- the page would always come up, but the 
images/stylesheets would be intermittently missing.

I found that once TUX passes the socket, it has no more interaction with 
the socket from that moment on.  This means that if Apache or some other 
web server keeps the connection open for the second request, third 
request, etc., TUX will have nothing to do with it even if it's a static 
file with the appropriate permissions.

I came across this because my back-end server did not handle static 
content at all (I was relying on TUX for this).  TUX would get the page 
request, not see the static file because the page is dynamic, Apache 
would handle the request, leave the connection open, get the second 
request from the browser, not find a handler for that URL, return a 404, 
and close the connection.  The browser would open a connection again for 
the third request and get TUX again, this time serving the static content.

The effect of course is that the page would come up with no stylesheet, 
but all of the images would load.  Since expiry was set for some 
content, a reload would alternate the missing item.

---

I'm sending this email as a cautionary tale for others so that they 
don't waste time in frustration.  In situations like this, disabling 
keep-alives on the dynamic server will solve the problem.  
Unfortunately, this requires the tear-down/rebuild step for a new socket 
on every page request, but c'est la vie.

The only real solution that I can see would be to add support to TUX for 
watching the socket after it has passed it to userland -- in other 
words, make it more like a full proxy instead of a simple relay race.

If anyone has any ideas on this, I'd love to hear them.  Unfortunately 
this is a programming task beyond my current abilities to fix -- I can 
fix simple kernel bugs, but I don't add significantly new functionality.

- Miles