Adds a "Served-By" header to requests served by Tomcat. Useful for clusters.
Add the valve to a host in server.xml:
<Host name="localhost" appBase="webapps" unpackWARs="true" autoDeploy="false" xmlValidation="false" xmlNamespaceAware="false">
<Valve className="com.boston.tomcat.valve.ServedByHeaderValve" />
</Host>