Following are the steps to generate a web viewer which can work in Standalone Tomcat:
1. Before create a web viewer, make sure that DTP ODA binary is setup in your Eclipse
   Please use the latest stable build of DTP, you can download it from http://www.eclipse.org/datatools/downloads.html
2. Use Ant Build to call Jar target in BuildWebViewer.xml to create web viewer framework
   When build is successful, birt_web is created under root of viewer plugin, and web viewer framework is put under birt_web.
3. Download iText1.3 from http://prdownloads.sourceforge.net/itext/itext-1.3.jar, copy it to birt_web/WEB-INF/platform/plugins/com.lowagie.itext/lib folder
4. After above steps, birt_web can be deployed in Tomcat