You need to have the AJAX URL formed in a way that invokes a controller. eg /application_name/controller_name/function_name/arg0/arg1 .....
and include the variable(s) you want to send back. The variables can be either addition items after the function as above where they show up as args or if they are part of a form POST then the variables would be in the vars dict. The controller will then validate the variables if need be and store what it needs to in the session. You don't need a view for this.