Oracle Magazine - September/October 2011

af:trainButtonBar components to render the train model in the UI.

Expand the sample application’s View Controller project in the Application Navigator. Open the Web Content folder and its WEB-INF folder, and then double-click employees-btf.xml to open it in the task flow visual editor.

Next, open the Oracle JDeveloper Structure window (Ctrl-Shift-S). Under ADF Task Flow, select task-flow-definition – employees-btf. Open Oracle JDeveloper’s Property Inspector feature (Ctrl-Shift-I), and scroll to the Behavior section. You can see that the Train property is set to true to expose the task flow train model at runtime. (The default value is false.)

DEFINING TRAIN STOPS AND THE
NAVIGATION SEQUENCE

After enabling a bounded task flow to expose a train model, you need to define view activities and task flow call activities as train stops. To add an existing view or task flow call activity to the train model, select the activity in the visual editor, right-click, and then select the Train option to create (or, later, to change) the train stop setting. Any view and task flow call activities you add to the task flow diagram are automatically added to the sequence of train stops.

The navigation sequence is defined initially by the order in which view activities and task flow call activities are added as train stops. You can easily change this order via the Train option in the context menu associated with each activity.

Train stops are further configured with the Property Inspector. To see how, select the EmployeeDetails view activity in the sample application’s employees-btf.xml task flow and open the Property Inspector. Scroll to the Train Stop section to see the train stop properties, as shown in Figure 3.

The Train Stop section appears in the Property Inspector only if the bounded task flow’s Train property is set to true and the selected activity is either a view activity or a task flow activity.

Figure 3: Train stop configuration properties for the EmployeeDetails view activity

TRAIN STOP PROPER TIES As you can see in Figure 3, train stops are configured with five properties:

1. The Train Stop property is set to false by default. When set to true, it indicates that the view or task flow call activity is a train stop. You set this property at design time and cannot change it at runtime.

2. The Outcome property enables you to associate a control flow name with a train stop to define an alternative navigation case. The Outcome property can be read from Java code at runtime but not changed then.

3. The Sequential property defines the order in which users navigate the train stops. If a train stop’s Sequential property is set to true, users can access that stop only if they have already visited the preceding stop. A value of false defines nonsequential navigation, enabling the user to select any train stop whose Skip property is not set to true. You can use Expression Language (EL) to define the Sequential property value for a train stop dynamically. The sample application for this column demonstrates this usage.

4. The Skip property disables a train stop so that users cannot navigate to it. Like the Sequential property, the Skip property can be dynamically changed at runtime.

5. The Ignore property prevents a train stop
from rendering in the UI. Although you
can use EL to set the Ignore property
value dynamically at runtime, it can be
changed only upon task flow initializa-
tion. Once a task flow is rendered, the
Ignore property is immutable.

BUILDING THE TRAIN USER INTERFACE Oracle ADF Faces provides two UI components for displaying train models in your JavaServer Faces pages and page fragments:

1. The train component, af:train, displays the train model as a horizontal or vertical line with icons indicating the stops. The train component is used for both sequential and nonsequential navigation.

To define display names for each stop, you edit the task flow. If it’s not open already, double-click the employees-btf.xml file in the Application Navigator and expand the EmployeeDetails view activity node in the Structure window. Expand the train-stop node, as shown in Figure 4, to see the Display Name configuration. You add the display name element by using the right-click context menu on the train-stop node and selecting Insert inside train-stop -> Display Name. You then edit the Display Name value with the Property Inspector.