Oracle Application Express installs with your Oracle database and consists of data in tables and PL/SQL code.
Whether you run the Oracle Application Express development environment or an application you built using Oracle Application Express, the process is the same. Your browser sends a URL request that is translated into the appropriate Oracle Application Express PL/SQL call. After the database processes the PL/SQL, the results are relayed back to your browser as HTML. This cycle happens each time you either request or submit a page.
The application session state is managed in the database tables within Application Express. It does not use a dedicated database connection. Instead, each request is made through a new database session, consuming minimal CPU resources.
About the Application Express Engine
The Application Express engine renders and processes pages. It also performs these tasks:
Session state management
Page flow control
Different Oracle Application Express Environments
When you install Oracle Application Express, you can install two different environments:
A runtime environment is the appropriate choice for production implementations in which users can run applications that cannot be modified.
A full development environment provides complete access to the Application Builder environment to develop applications as described in this document.