ADF Task Flows

A Fusion web application is broken up into a collection of reusable task flows. A task flow represents an activity that is performed when running that task flow.

Task flows can be bounded or unbounded. There can be only one unbounded task flow in an application, which contains the entry points of the application, if the application has more than one. If your application has a single entry point, it is no necessary to define an unbounded  task flow. However, even if empty, an unbounded task flow will always exist as the first  entry on the application's task flow stack.

Some task flow components and their definitions are enumerated below.

Activities

• View Activities: Display a page or page fragment
• Flow Calls: Invoke another task flow from within a task flow
• Task Flow Return Activities: Specify the outcome returned to the caller

Control Flow Cases:  Identify how control passes from one activity to another

Outcomes: Labels on control flow cases representing values that determine the following activity (e.g. values specified in the action attribute of the UI component)

Control Flow

• Control Flow Rules: Are invoked by components used to implement navigation on pages(links, buttons, trains, tabs, breadcrumbs); Are stored in task flow configuration files
• Wildcard Control Flow Rules: Global navigation rules(Rules that can be called from any  page)

An example of task flow design using JDeveloper is shown in the following picture. The yellow triangles show that the respective activities do not point to pages yet.

An example of task flow design

Planning the User Interface in Oracle ADF

1.Describe the Model-View-Controller design pattern
http://javing.blogspot.com/2011/02/web-programmers-most-powerful-weapon.html?spref=bl

2.Differentiate between bounded and unbounded task flows
"An ADF bounded task flow is used to encapsulate a reusable portion of an application. A bounded task flow is similar in some ways to a Java method." 
"A Fusion web application always contains an ADF unbounded task flow, which contains the entry point or points to the application."
(Bounded Task Flows)
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.
(Introduction to ADF Task Flows )

• There is only one unbounded task flow within an application. Even if you use multiple definition files for unbounded task flows within the application, they will be combined into a single flat namespace at runtime with the entire flow being loaded into memory at startup.
• Any view activity in the unbounded flow is URL accessible by the user.
• Unbounded task flows are restricted to view activities that are implemented as whole pages.
• Bookmarking is only supported by views in an unbounded task flow and is not available in bounded task flows.  (Task Flow Design Fundamentals, An Oracle White Paper, April 2011 )

3.Create task flows to define control flow in an application
http://download.oracle.com/docs/cd/E21764_01/web.1111/b31974/taskflows.htm#ADFFD21726

4.Specify control flow rules
 When the user acts on a command component(e.g. button,link) in a JSF application, a rule is invoked to determine the next page to display. These rules are called control flow rules. They can also be invoked by tabs, breadcrumbs or train components. Control flow rules can be defined using one of the following:

• the visual editor (Navigation Modeler)
• the Configuration editor (XML Console)
• the XML file directly
• the Structure window

5.Define global navigation
A global control flow rule is a rule that applies for all pages (that is a rule that can be called from any page). Use the wildcard control flow rule element in the Component Palette of JDeveloper to define a global control flow rule.

6.Use routers to declaratively route control flow to activities based on an EL expression
http://download.oracle.com/docs/cd/E17904_01/web.1111/b31974/taskflows_activities.htm#ADFFD1673

7.Define the role of managed beans in task flows
Managed beans are registered with the application in task flow .xml files.
http://download.oracle.com/docs/cd/E21764_01/web.1111/b31974/web_getstarted.htm#CACCFIII

8.Explain the types of validation available in the user interface

• UI component attributes for validating data (e.g. required)
• default validation
• custom validation