I'm struggling with Java String Url to call Apex Page .

Calling from Form Personalization works fine ->

Function: XX_APEX_PAGE1
Parameters : ='p=100:9999:::::EBS_SESSION,APEX_PAGE_ID,P5_INVOICE_ID:[EBS_SESSION],5,'||:INV_SUM_FOLDER.ATTRIBUTE15

Now I want to execute this function in OAF Custom Page

I got OALinkBean
and trying to do somethink like this..

             String url =
                 "RF.jsp"
               + "?function_id=59085"
               + "&resp_id=" + "50838"
               + "&resp_appl_id=" + "200"
               + "&security_group_id=0"
               + "&lang_code=US"
               + "&p=100:9999:::::"
               + "&APEX_PAGE_ID=5" 
               + "&P5_INVOICE_ID=" + attribute15;

OALinkBean b = (OALinkBean)webBean.findChildRecursive("OpenInvoice");      
b.setTargetFrame("_blank");
b.setDestination(url);

but ofcourse it does not work...

Can anyone can tell how to build corrent url string ?