This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Validation can be done thru either client side or server side. But in struts, validations could be done thru ActionForm bean class. This is because, Just imagine like this, you have a login form, user enter a name and password. If the name and password is correct, then absolutely no problem he/she may get successfull page. But what will happen, if the password is wrong. This kind of validation can not be done thru java script. And also when the user click on loginAgain link then you should not diplay blank/empty in the user field. Instead of that you should dislay what he/she entered user name so that they can clarify if the user name is wrong or they enter only password and they can go to success page. This is what I understood from struts. If u want further details on this, refere some struts book or reply me so that I can send the code.