To run JWIG web applications, you need:

 - Java 6 (see http://java.sun.com/javase/downloads/)
 - Apache Ant 1.7 (see http://ant.apache.org/bindownload.cgi)
 - Tomcat 6.0 (see http://tomcat.apache.org/download-60.cgi)
   or Resin 1.6 (see http://www.caucho.com/download/)

(or later versions)
Note that Java 5, Ant 1.6.5, and Tomcat 5.5 are *not* sufficient.
 
The default Tomcat configuration needs a small modification: 
In conf/server.xml, replace the attribute 

  protocol="HTTP/1.1"
  
in the main Connector element with

  protocol="org.apache.coyote.http11.Http11NioProtocol"
  URIEncoding="UTF-8"
  
If you use Resin instead of Tomcat, you need to replace the
servlet class for the Synchronizer servlet in 
web/WEB-INF/web.xml to:

  dk.brics.jwig.server.resin.ResinCometHandler