Jruby deployment on Glassfish v3: index.html replacment

Hi,

I deploy my JRuby application on a Glassfish V3 server. In general
eveything works fine and the performance is perfect. But there is a
small problem.

If I enter the url www.mydomain.net/myapp into the browser I can use my
application as expected. If I enter www.mydomain.net I get the Glassfish
standard file index.html displayed. How can I replace or change
index.html to get redirected to my application??? I do not use Apache
as I use Glassfish on ports 80 and 443.