[fw-mvc] Zend Form: chained select

Hi to all,

I want to chain two (or more) select so when I change option in the
first select, the second will be populated with new value from a JSON
request or similar.

However I don't know how to do this...

I've created a form with Zend_Form, with only the two select
element... but:

1) How I can send a request when the value of first select change?
2) How I can set the new options for the second select?

I've also write a controller who send a JSON response but I don't know
how to parse this request client-side or to send parameters to this
action/controller.

I can use Dojo for this? I've read many many pages of documentation
and reference without find what I need.

Thanks in advance.

---
Emanuele Deserti
Netwing S.r.l.
<emanuele.deserti@netwing.it>
Tel. 0532 - 1912002
http://www.netwing.it