The jetty.xml file is a default configuration file for Jetty and is located at
$JETTY_HOME/etc/jetty.xml. You can call the file anything and it can be located anywhere in the filesystem. It is supplied to jetty on the runline like so:
You can also have more than one configuration file. If you specify more than one on the runline, a single Jetty instance will be started with one org.mortbay.jetty.Server instance per configuration file. Eg:
The jetty configuration format is a simple mapping from XML to java. With this format you can call the methods defined in the javadoc to configure a server. There is a more in-depth look this syntax and the jetty.xml file in the XML Configuration Reference section.
If you need to perform more specific setup on a webapp, you can use the jetty-web.xml file.