If you’re using Tomcat and you are looking into moving to GlassFish (because of Java EE 5, admin tools, Grizzly performance, etc…), you might find this question I was asked twice recently about a specific feature migration.
If you were using Tomcat’s Context feature and reading the initialization parameters say from
servletContext.getInitParameter(), you need to provide the same information in a slightly different format in the standard
web.xml deployment descriptor.
Note this can also be added to
$GLASSFISH_HOME/domains/$DOMAIN_NAME/config/default-web.xml if you don’t want to repeat this in all your web-apps. But be careful as it takes precedence over the web application