Creating Task Flow bindings on the fly

A very common demand from the community was support for adding regions at run time. The good news is that 11.1.2 release has support for adding regions dynamically which is now well supported by a task flow binding layer as well. Wow...excited? Please see
21.10 Configuring a Page To Render an Unknown Number of Regions in developers fusion developers guide to learn more about this topic. Let me give you a quick overview on the implementation. Its very easy.


1. Build the logic to return TaskFlowBindingAttributes list for dynamic task flows

First step is to build a managed bean to hold your business logic for building list of oracle.adf.controller.binding.TaskFlowBindingAttributes as shown in the following code snippet.

 private List<TaskFlowBindingAttributes> taskFlowBindings = new ArrayList<TaskFlowBindingAttributes>();  
   
 public void buidTaskflowBindings(){  
   
  TaskFlowBindingAttributes tfBindAttr1 = new TaskFlowBindingAttributes();  
  tfBindAttr1.setId("region1");  
  tfBindAttr1.setTaskFlowId(new TaskFlowId("/WEB-INF/dept-task-flow-definition.xml", "dept-task-flow-definition"));  
  taskFlowBindings.add(tfBindAttr1);  
    
  TaskFlowBindingAttributes tfBindAttr2 = new TaskFlowBindingAttributes();  
  tfBindAttr2.setId("region2");  
  tfBindAttr2.setTaskFlowId(new TaskFlowId("/WEB-INF/emp-task-flow-definition.xml", "emp-task-flow-definition"));  
  tfBindAttr2.setParametersMap("#{pageFlowScope.MyBean.parameterMap}");  
  taskFlowBindings.add(tfBindAttr2);  
 }  
   
 public List<TaskFlowBindingAttributes> getTaskFlowBindings() {  
  return taskFlowBindings;  
 }  
   

2. Generate the executable entry for multi task flow in the page definition file

Switch to the binding tab of your page, click on the '+' icon under the Executables section to generate the binding for multiTaskFlow. Please see the following image.

You may need to key in a unique identifier for the <multiTaskFlow> entry, and a value for taskFlowList as well. The taskFlowList will take an EL expression that returns the list of TaskFlowBindingAttributes at run time. In our case the method getTaskFlowBindings() returns the list(please refer this method in above code snippet).

Note: The multi task flow binding (multiTaskFlow) in the page definition identifies a list of bounded task flows used in the ADF region.

  <multiTaskFlow id="multiRegion1"   
  taskFlowList="#{pageFlowScope.MyBean.taskFlowBindings}"  
  xmlns="http://xmlns.oracle.com/adf/controller/binding" activation="deferred"/>  

3. Build the UI to host regions at run time

The last step is building the UI to host regions at run time. This example uses af:forEach for adding regions at run time as shown in the following page snippet.

 <af:forEach var="tf" items="#{bindings.multiRegion1.taskFlowBindingList}">  
  <af:region value="#{tf.regionModel}" id="reg${tf.name}"/>  
 </af:forEach>  

Update on July 17, 2014
While EL binding the IDs( for e.g id="reg${tf.name}" in the above code snippet) you must use immediate EL such as id="reg${tf.name}", NOT the deferred EL such as id="reg#{tf.name}".

Notes(from Fusion Developers Guide):

• Limit the number of ADF regions that you create in a page to 10.

• Each task flow binding inherits attributes defined for the multi task flow binding unless you override this behavior using the methods exposed by TaskFlowBindingAttributes.

• Each task flow binding inherits parameters defined in the multi task flow binding in addition to those defined using the parametersMap property.

Download

You can download the sample workspace from here.
[Runs with Oracle JDeveloper 11.1.2.0.0 (11g R2) + HR Schema]

A glance at the implementation

Run the main.jsf page and click on the 'Display More Taskflows' button.
You may notice that two task flows are getting added on the screen when you click on the button.


Learn More ...

There are a lot more points like this. If  you are curious to learn the internals of the ADF Business Components and ADF Binding Layer,  the following book is for you - Oracle ADF Real World Developer’s Guide.
More details about this book can be found in this post- http://jobinesh.blogspot.in/2012/07/pre-order-your-copy-of-oracle-adf-real.html