How to use ajax with prototype and jsps

I'm developing social faq solution.

When I click on vote up or vote down, i want to make an ajax call to a java function.

I've worked with struts on another project, and i was making call to struts action.

Now I work only with simple jsp, servlets ..开发者_如何学编程. and I dont know how to make an ajax call to a java function which will send me json or xml.

• Prototype Ajax Tutorial
• Ajax for Java