what is there in it? Am i missing something? Am on the same page as yours..
Anyways, it is same as how you get the data in your parent read, it from the infrastructure of your application. It can be from any scope - the application (retrieve from the static variables in child window), session(retrieve from the session which you would set before opening child window), request (same from request). how to set these values in different scope is the actual story. Say if you are not processing any request in the server side to open the (somewhat called static
JSP) child then you can just put it in the URL (like childURL?parameterName=value) but it is not recommended for security reasons and not a good practice.