OAF Basics

With arrival for R12 and now Oracle Fusion, oracle is moving from Forms based interface to
Web based UI. So now days there is a buzz of OAF and ADF which has been the bases for development
of these Web based UI for Oracle ebiz.

Oracle Application Framework(OA Framework) is a proprietary framework developed by Oracle Corporation for application development within the Oracle E-Business Suite.
OA Framework is an architecture for creating web based front end pages and J2EE type of applications within the Oracle EBS ERP platform. In order to develop and maintain OAF functionality, Oracle's JDeveloper tool is used. OA Framework uses the UIX other XML technologies for building the components.

OA Framework is based on J2EE technology called BC4J (Business Components for Java)
The OA Framework is a Model-view-controller (MVC) framework built using J2EE (Java 2 Platform, Enterprise Edition) technologies.

                              

EO(Entity Objects)
Entity Object is based on database table or other data source.Entity Object contains attributes which represent database columns.All insert/update/delete (DML Operations) transactions go through EO to database.

VO:
View Objects are based on EO or SQL Query which is again based on EO Objects
Two types
1. SQL based
2. EO based
Basically VO is synonymous to views used in PLSQL Programming they are used for joining tables, filtering based on conditions and sorting the data. Entity Objects can be based on any number of
EO and provide access to EO.

Application Module:
Its a container for VO. Once you create a Application Module you need to associate the corresponding
VO to the Application Modules. Access to the VO is always provided through the Application Module.
Every Page in OAF Framework need to be associated with a AM.

Controller:
When user clicks a button, or performs certain action what responses should be triggered is coded in the
Controller. All the responses to User actions, Application Flow is coded into the Controller. m
Model objects like EO and VO can't be accessed directly from the Controller Class, except AM.

Some common methods that controller has
1. ProcessRequest: Fires when OAF page loads for the first time
2. ProcessFormRequest: Fires when user submits the page.

Below is the Onion ring MVC architectural representation, it explains how the security/encapsulation of
each layer happens when an OAF application is build.