Well, you
could do something like that, but I'd not use JSON to go
to the server. JSON is great for data coming from the server, because it's a natural format for JavaScript to digest. Not so much for the other direction.
The most natural way for server code to get array data (especially if using Servlets) is the traditional query parameter format.
That said, JSON server libraries are getting more popular (I use Stringtree) so if you did want to pass a JSON
string back to the server, I'm sure you can find a way to digest it. I'm just not so sure it's the best (aka simplest) approach.