Q:

Apache mod_rewrite internally to different port

Is it possible to internally redirect (so url won't change in address bar) with mod_rewrite to different port on same host?
Eg
http://host.com:8080 -> http://host.com:9999/myapplication/?param=val

A:

1, Enable mod_proxy
LoadModule  proxy_module         modules/mod_proxy.so
LoadModule  proxy_http_module    modules/mod_proxy_http.so

2, You should configure apache for vhost :
<VirtualHost *:8080>
    ....
    ProxyPass / http://host.com:9999/myapplication/?param=val
    ProxyPassReverse / http://host.com:9999/myapplication/?param=val

</VirtualHost>

3, Setup also VHost on port 9999
More info here:

http://httpd.apache.org/docs/2.2/mod/mod_proxy.html 
http://www.apachetutor.org/admin/reverseproxies

