Just see what you can get from this perfect self explained diagram.
If you can completely understand the struts-config.xml => you would know the rest easily.
Opinion: For any interview, it is always good to say -'I have never worked on it' rather than saying something that you think that you know but actually do not know. Slowly you would get to know. Concentrate on your strengths.
Have Fun with Java
little,little.. little by little makes a lot..