For those who do not know (yet), Oracle Application Express (APEX) is Oracle’s database-centric Rapid Application Development (RAD) tool, used to fast-develop web applications with SQL and PL/SQL.
All editions of the Oracle Database have APEX installed by default, and you do not need to pay for it, provided you have purchased the database license. Inside APEX, you can use or study the built-in packaged applications – like Customer Tracker or P-Track (Project Tracker). Of course, this is not a kiddy tool - one example of a large APEX application, developed by Oracle, is the Oracle Store itself here.
APEX is also available in the Oracle Public Cloud, as a part of the Database Schema Service. For details on this service, you can go to this link.
A friend asked “Most of my applications are in Oracle Application Express. I want to use the Enterprise Manager Diagnostics and Tuning Packs, and I want to know if I can monitor pages, modules and/or applications of APEX in Diagnostics Pack using EM 12c.”.
Well, although there is no direct application-level integration between Enterprise Manager and APEX, you can use the Diagnostics and Tuning Packs to diagnose and tune the APEX application database, in the same manner as you would use the packs to do this for any other database. This is because APEX is very much database-centric.
The other possibility is to use Oracle Real User Experience Insight (RUEI) to monitor the APEX end user pages, and find out which pages are slow (based on the page load time dimension in RUEI), and then drill down to the database level. RUEI is explained in my article series here.