OAF MVC Architecture


OAF is a java based application framework to develop web based applications that link to Oracle Applications instance while maintaining all the security features of that apps instance. A framework is a specialized set of related classes designed to make application development easier.  In effect, a framework implements part of an application so developers don’t have to write all of its code from scratch; they can use the framework as the basis for their work and while focusing on the additional code required to implement their specific application requirements.

OA Framework follows Model, View and Controller (MVC) Architecture as described below:

1] Model

Model contains the components which handles data directly from Database. It Includes Business Components for Java (BC4J Objects) which mainly are:

Entity Objects (EO):

Entity Objects are generally based on one table which encapsulate the business rules. These objects are used by OAF page to perform update/insert/delete operations. You can join two EOs using Entity Associations.

View Objects (VO):

These objects contain a SQL query that queries the data from database and present it in the OAF page. VOs can be based on one or many EOs or a SQL query. Two VO can be linked together through a View Link.

Application Module (AM):

It is a container for related BC4J objects and provides the database connection. It also provides Transaction Context (OADBTransaction) or Transaction Management. An AM can have more nested AM contained in it along with other BC4J components. But it is mandatory to have an AM for an OAF page.

2] View

View contains the actual page items on page which user can see. The view in OAF comprises of various page level items like text fields, buttons, regions, links etc. These items are visible on any OAF page. These items can either be tied to VO attribute or having a constant value or populated at run time based through controller logic.

Please note that- View Layer is altogether different than View Object!!!!!

3] Controller

Controller handles all the user actions done on the page. OAF requires a java controller class to be defined for a page/region which handles various page level actions. The important methods in this class are:

A] ProcessRequest

     This request is called when page is rendered. Any logic to be executed during page initialization is kept here.

B] ProcessFormRequest

Any page submit action causes ProcessFormRequest to be executed. The logic put here typically is that which needs to be executed after actions like button click or any other page submit action.

The Controller class is mostly used to put logic for actions on page such as button clicks, navigation to other pages. The two objects that are passed to controller methods are OAPageContext and OAWebBean. OAPageContext provides access to objects like AM class, page parameters, session values, navigation methods. OAWebBean is generally used to get a handle of page items.

In coming posts, I will try to write more details about these components and how they works….so stay tuned!

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The ADF Architecture


The Oracle Application Development Framework (ADF) is an end-to-end application framework that builds on Java Platform, Enterprise Edition (Java EE) standards and open-source technologies. It abstracts Java EE complexity and provides developers a declarative and visual development.

The Oracle ADF implements the Model-View-Controller (MVC) design pattern and offers an integrated solution that covers all the layers of this architecture with solution to such areas as: Object/Relational mapping, data persistence, reusable controller layer, rich Web user interface framework, data binding to UI, security and customization. Extending beyond the core Web based MVC approach, ADF also integrates with the Oracle SOA and WebCenter Portal frameworks simplifying the creation of complete composite applications.

The Oracle ADF architecture is based on four layers:

The Business Services layer:

  • It simply provides the access to data from various sources and handles the core business logic.
  • ADF has its own technology for this layer and we call this part as ADFbc (ADF Business Components). ADFbc facilitates backend service for query, create, update, delete operations and provide lot of features to implement validations and business logic.
  • This layer also can be implemented by
    • Simple Java Classes
    • EJB
    • Web Services
    • BAM
    • BPEL
    • Portlets etc.

The Model layer:

  • This layer connects the business services to the objects that use them in the other layers.
  • Oracle ADF provides a model layer implementation that sits on top of business services, providing a single interface that can be used to access any type of business services listed above.
  • It consists of two components, data controls and data bindings.
    • Data controls abstract the business service implementation details from clients.
    • Data bindings expose data control methods and attributes to UI components, providing a clean separation of the view and model.

The Controller layer:

  • This layer provides a mechanism to control the flow of the Web application and handles user input.
  • For example, when you click a Search button on a page, the controller determines what action to perform (do a search) and where to navigate to (the results page).
  • We have two controller options in JDeveloper.ADF Controller provides an enhanced navigation and state management model on top of JSF.
    • The standard JSF controller
    • The ADF Controller
  • JDeveloper allows you to declaratively create task flows where you can pass the application control between different types of activities, such as pages, methods on managed beans, case statements, or calls to other task flows.

 The View layer:

  • The view layer is the top most layer, that user sees and interacts with.
  • It contains the UI pages used to view or modify that data.
  • For Web based interface Oracle ADF offers a rich set of over a 150 Ajax enabled JSF components that simplified the creation of dynamic and appealing user interfaces.
  • It also supports Apache myfaces Trinidad components, Java and ADF Swing components and also has ADF Mobile components that are specifically built for Mobile applications.