ADF Concepts

The Oracle Application Development Framework (Oracle ADF) is an end-to-end
application framework that builds on J2EE standards and open-source technologies to simplify and accelerate implementing service-oriented applications. If you develop enterprise solutions that search, display, create, modify, and validate data using web, wireless, desktop, or web services interfaces, Oracle ADF can simplify your job. Used in tandem, Oracle JDeveloper 10g and Oracle ADF give you an environment that covers the full development lifecycle from design to deployment, with drag-and-drop data binding, visual UI design, and team development features built-in.

Business Component In ADF

All of these features can be summarized by saying that using ADF Business
Components for your J2EE business service layer makes your life a lot easier. The key ADF Business Components components that cooperate to provide the business service implementation are:

Entity Object

An entity object represents a row in a database table and simplifies modifying its data by handling all DML operations for you. It can encapsulate business logic for the row to ensure your business rules are consistently enforced. You associate an entity object with others to reflect relationships in the underlying database schema to create a layer of business domain objects to reuse in multiple applications.

Application Module

An application module is the transactional component that UI clients use to work with application data. It defines an updatable data model and top-level
procedures and functions (called service methods) related to a logical unit of work related to an end-user task.

View Object

A view object represents a SQL query and simplifies working with its results. You use the full power of the familiar SQL language to join, project, filter, sort, and aggregate data into exactly the “shape” required by the end-user task at hand. This includes the ability to link a view object with others to create master/detail hierarchies of any complexity. When end users modify data in the user interface, your view objects collaborate with entity objects to consistently validate and save the changes

ADF Task Flows

ADF task flows provide a modular approach for defining control flow in an application. Instead of representing an application as a single large JSF page flow, you can break it up into a collection of reusable task flows. Each task flow contains a portion of the application's navigational graph. The nodes in the task flows are activities. An activity node represents a simple logical operation such as displaying a page, executing application logic, or calling another task flow. The transactions between the activities are called control flow cases.

Task Flow Types

The two types of ADF task flow are:

Unbounded task flow: A set of activities, control flow rules, and managed beans that interact to allow a user to complete a task. An ADF unbounded task flow consists of all activities and control flows in an application that are not included within any bounded task flow.

Bounded task flow: A specialized form of task flow that, in contrast to an unbounded task flow, has a single entry point and zero or more exit points. It contains its own set of private control flow rules, activities, and managed beans. An ADF bounded task flow allows reuse, parameters, transaction management, and reentry.

JSF fragments

JSF page fragments are page definitions that run embedded in another JSF page. Fragments are like page includes in JavaServer Pages, with the difference that in Oracle ADF Faces they are usually used in the context of ADF regions or dynamic declarative components. You can also reference page fragments directly from a JSP includes tag added to a JavaServer Faces document (JSPX). However, in this case, and only if a page fragment has ADF bound content, you need to make sure the content of the page fragments ADF binding file (PageDef) is copied to the PageDef file of the parent page. Otherwise ADF queried data will not show.

ADF regions 

ADF regions consist of an ADF Faces af:region tag, an ADF bounded task flow and page fragments. Page fragments that are used in a bounded task flow don't need to copy their ADF binding references to the parent container, which is a huge difference between JSP includes and ADF regions. ADF regions define an interactive area on a view, a JSF document or another JSF page fragment, that developers use to show a single view or a complete, multi-step, process. ADF regions can be statically or dynamically defined. In either way they require a PageDef file and a bounded task flow to reference. ADF regions help building desktop like web applications in which users stay for long on a single page while working on a business task.

Declarative components

Declarative components allow developers to build a composite component out of existing ADF Faces components. Declarative components exist in two flavors: library driven and dynamic declarative components (ddc). The tag library driven components are declaratively built from the File | New menu option. In the JSF view option you find a declarative component menu option that steps you through building your own ADF F aces component from existing ADF Faces components. You use tag library driven declarative components to build custom components with behavior, like a tool bar or a custom file-upload handler. The goal of building declarative components is to build re-usable components that simplify development and administration by avoiding duplicate page codes. Dynamic declarative components (DDC) are used within the scope of the web application they are defined in and cannot be re-used across applications. Their main usage is to build reusable layout artifacts or page area components. For example, a custom tab canvas is what you would build using DDC components.

Page templates

Page templates are layout definitions that you use as a starter when building new pages to enforce consistent page layouts throughout applications and enterprises. Best practices are to build a page template using the ADF Faces Quick start templates. You cannot nest page templates, but you can use page templates on parent and child views (page fragments). A page template is the page level equivalent to a DDC component.

ADF Library

ADF libraries are special Oracle ADF archive files that you use to reuse bounded task flows (regions), page templates and declarative components. They are standard JAR files with extra information in the archive manifest file that allows you to import the library files into the Oracle JDeveloper Resource Palette for declarative reuse.