1. Struts 2: the modern web application framework

Question 1

What is a Framework?

Answer 1

Piece of structural software. It tries to make generalizations about common tasks and workflows. These generalizations (conventions over configuration) allow applications to be built more quickly.

Question 2

What do Interceptors do?

Answer 2

Run before an action, and after a result.

They don’t HAVE to do something both times, but they have the opportunity to.

Question 3

What’s the purpose of interceptors? Think of a good example for an interceptor.

Answer 3

They allow common cross-cutting tasks to be defined in clean, reusable components.

Logging could be a good example, we want to log all requests but it doesn’t belong in any single actions unit of work.

Question 4

What is the ValueStack? Explain what it does.

Answer 4

It’s a storage area that holds all of the data associated with the processing of a request.

Think of it as a piece of scratch paper where the framework does its work while processing a request. Rather than passing this data around, it’s kept in a central location–the ValueStack.

Question 5

What is OGNL?

Answer 5

It’s an expression language that allows us to access the data we put in the ValueStack.

Question 6

What context is the ValueStack stored in?

Answer 6

Inside the ThreadLocal context called the ActionContext.