ORACLE APPLICATIONS R12 ARCHITECTURE

Oracle E-Business Suite Release-12 have a Multi-tiered Architecture, that supports Oracle Applications products.
They are comprised of a Database Tier which manages the Oracle Database and stores all data.
An Application Tier hosts various servers, manages communication between the desktop and database tier and contains the application file system.
A Client Desktop through which user access Oracle Applications.

Architecture-R11i vs R12

1. Desktop Tier

The client interface is provided through HTML for HTML-based applications, and via a Java applet in a Web browser for the traditional Forms-based applications.
In Oracle Applications Release 12, each user logs in to Oracle Applications through the E-Business Suite Home Page on a desktop client web browser.
The E-Business Suite Home Page provides a single point of access to HTML-based applications, Forms-based applications, and Business Intelligence applications.
Oracle JInitiator will no longer be required to run Oracle Forms in E-Business Suite Release 12.
Oracle Forms in Release 12 will run directly in the native Sun Java2 Standard Edition plug-in.
The Forms client applet is a general-purpose presentation applet that supports all Oracle Applications Forms-based products, including those with customization and extensions.
The Forms client applet is packaged as a collection of Java Archive (JAR) files.
The JAR files contain all Java classes required to run the presentation layer of Oracle Applications forms.

The application tier has a dual role, hosting the various servers and service groups that process the business logic, and managing communication between the desktop tier and the database tier.
This tier is sometimes referred to as the middle tier.
Four servers or service groups comprise the basic application tier for Oracle Applications:

The database tier contains the Oracle database server, which stores all the data maintained by Oracle Applications.
The database also stores the Oracle Applications online help information. More specifically, the database tier contains the Oracle data server files and Oracle Applications database executable that physically store the tables, indexes, and other database objects for your system.
The database server does not communicate directly with the desktop clients, but rather with the servers on the application tier, which mediate the communications between the database server and the clients.