31 May 2014

Working with Bindings in a Task Flow Finalizer

Sometimes we need to access the business service layer in a task flow finalizer. For example, in order to clean up some resources we have to invoke an application module method in a finalizer. But a task flow finalizer is not an activity, therefore it can't have its own page definition file and we are not able to use the bindings layer in order to invoke the application module method. So, we have to get a reference to the application module instance and work with its methods directly. That's not really cool. This is kind of a rule violation. Let's see what we can do about that.

We're going to manually create a page definition file for the task flow finalizer and we are going to access the binding container in the finalizer method programmatically. So, in order to create a page def file we are going to drag-n-drop the AM method to the task flow diagram as a method call:


Jdeveloper is going to create a page def file for the method call and it's going to register the page def file in the DataBindings.cpx. So, in the DataBindings.cpx we'll have a page map:

 <page path="/WEB-INF/task-flow-definition.xml#task-flow-definition@someAMMethod"
   usageId="com_cs_blog_finalizerbindings_view_task_flow_definition_task_flow_definition_someAMMethodPageDef"/>


Actually we can remove it as we don't need it at all. And we'll have a page definition usage:

 <page id="com_cs_blog_finalizerbindings_view_task_flow_definition_task_flow_definition_someAMMethodPageDef"
   

path="com.cs.blog.finalizerbindings.view.pageDefs.task_flow_definition_task_flow_definition_someAMMethodPageDef"/>

Having done that, we can remove the fake "someAMMethod" method call in the task flow definition.
Now we are ready to implement a managed bean method for the task flow finalizer:
 public void taskFlowFinalizer() {
  //Get the current binding context
  BindingContext bc = BindingContext.getCurrent();
  
  //Find our binding container by name (page id in the DataBindings.cpx)
  DCBindingContainer dcb = 
    bc.findBindingContainer("com_cs_blog_finalizerbindings_view_task_flow_definition_task_flow_definition_someAMMethodPageDef");
  //Execute the method
  OperationBinding oper = dcb.getOperationBinding("someAMMethod");
  oper.execute();       
  }
That's it!

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