Why Combine Servlets & JSP?

Typical picture: use JSP to make it easier to 

develop and maintain the HTML content

For simple dynamic code, call servlet code from scripting 

expressions

For moderately complex cases, use custom classes called 

from scripting expressions

For more complicated cases, use beans and custom tags

But, that s not enough

For complex processing, JSP is awkward

Despite the convenience of separate classes, beans, and 

custom tags, the assumption behind JSP is that a single 

page gives a single basic look

103

JSP

www.corewebprogramming.com

Architecture

Approach

Original request is answered by a servlet

Servlet processes request data, does database lookup, 

accesses business logic, etc.

Results are placed in beans

Request is forwarded to a JSP page to format result

Different JSP pages can be used to handle different types 

of presentation

Terminology

Often called the  Model View Controller  architecture or 

 Model 2  approach to JSP

Formalized further with Apache  Struts  framework

See http://jakarta.apache.org/struts/

104

JSP

www.corewebprogramming.com

52