use varaible in one viusualforce page from another

Question

I have two visualforce pages (ParentPage and ChildPage) and one page include other. On ChildPage declared some variable which I want to use in ParentPage. Is it posible?

   <apex:page id="ChildPage">
        <apex:variable  var="isRegistered" value="true"/>
   </apex:page>


   <apex:page id="ParentPage">
       <apex:include pageName="childPage"/>

   ????? how to use variable "isRegistered"
   </apex:page>

Answer 1

You can pass variable value as a parameter in iFrame url. If you are resetting the value in parent page than re-render the section.