This graphic illustrates how the mid-tier handles requests for Web pages. The request originates in a user’s browser and makes its way across the internet to Oracle HTTP Server. If the incoming request is to display a Portal page, the HTTP passes it to the Parallel Page Engine, which forwards it to various Web providers who return content for the page. HTTP Server passes requests to execute PL/SQL code to mod_plsql, which then forwards them to the Oracle database for execution.