Core J2EE™ Patterns: Best Practices and Design Strategies, Second Edition

Chapter 6. Presentation Tier Patterns

Topics in This Chapter

• Intercepting Filter

• Front Controller

• Context Object

• Application Controller

• View Helper

• Composite View

• Service to Worker

• Dispatcher View

Intercepting Filter

Problem\

You want to intercept and manipulate a request and a response before and after the request is processed.

Preprocessing and postprocessing of a request refer to actions taken before and after the core processing of that request. Some of these actions determine whether processing will continue, while others manipulate the incoming or outgoing data stream into a form suitable for further processing. For example:

• Does the client have a valid session?

• Does the request path violate any constraints?

• Do you support the browser type of the client? ...