Unfortunately our budget for a load balancer hardware never got approved. So we had to think of ways to do software load balancing. We are using the HttpClusterServlet for our development environments. BEA recommends that it is best not to use this in production. We decided to use Apache proxy for proxying requests to the server.

More information here –
Weblogic Apache HTTP Plugin – http://download.oracle.com/docs/cd/E11035_01/wls100/plugins/apache.html
Apache mod_proxy – http://httpd.apache.org/docs/2.0/mod/mod_proxy.html

Both are excellent tools to enable dynamic, AJAX driven web interfaces.

From what I have seen so far,

I found Echo3 to be easier to understand, JDK 1.5+ support and most of our application operations are done on the server side. GWT would make too many calls to the server, and Echo3 is a clear winner here. Our application framework extensively uses Spring and Hibernate and Echo3 nicely plugs into these frameworks. GWT has a better user interface performance, if you have complex widgets which dont require too many calls to the server. We finally decided to go with Echo 3.