@sunarb
Think of three tiers:
1) the client tier; this tier runs a browser or some other client Java code.
2) the web tier; this tier runs your web server or Servlet container that sends pages of html or other data to the first tier.
3) the business logic tier: this tier runs your enterprise Java beans, your database connectivity code etc. This tier communicates with the second tier.
All together these tiers make up an 'enterprise application'; when you leave out the third tier you have a 'web based' application. The first tier by itself is just a desktop application if more than a browser is used.
Those second and third tiers have gone through many incarnations already; each claiming to be the final solution to it all. IMHO exactly the same mess as from their previous instantiations lives on in the latest instantiations with more 'technologies' and more 'frameworks' and more trouble ...
And a new mess is born with the new incarnations.
kind regards,
Jos