1.When do we go for jar files and when do we go for war files.And whats the difference between web-inf & meta-inf folders
war file represent a web module in your application.
Use jar files to bundle up the
java classes.Example Ejb-jar will contain
the
ejb classes.
web-inf folder is needed to build a web module.This folder will contain the web.xml which configure container for your web application.
meta-inf folder will have your deployment descriptor.Ex in ejb folder structure meta-inf directory will have the deployment descriptor for your EJB's.
2.Is there any tool which generates the DD files automatically other than weblogic builder.
Sun ONE Studio will create DD automatically.
Hope this will help you.
Cheers,
Senthil