Jgrid with JSON and httphandler

Hi, I am a newbie of JSON, httphandler and jqGrid
I have found the way to send JSON to client from server using httpHandler.
However, how to get the returned JSON from client? (Is my concept correct?)
Currently, I only found that I can get the edited value from
 
context.Request.Params.Item(context.Request.Params.Keys(0))
 
Are there other ways to get the edited value?
Thanks!
...