Introduction

Spring Web Flow has something called subflow which allows one webflow to invoke another webflow (possibly defined in a different module). When designed properly, webflow allows collaboration of disparate modules.

Get started with subflow

1. Define a subflow-state

       <!-- id: handle for this subflow.
            subflow: registered webflow name. by convention, spring names webflow by using the XML definition filename minus .xml. -->
       <subflow-state id="questionGroupStep" subflow="questionnaire">
           <transition on="viewClientDetails" to="selectCustomerStep"></transition>
       </subflow-state>
   

   
   In this example, the subflow is called "questionGroupStep". It will invoke the "questionnaire" webflow when a state transition to "questionGroupStep" occurs. When the subflow exits, a transition to "selectCustomerStep" state will occur.
   
   
2. To invoke the subflow, simply use the subflow's ID as the target of state transition:

       <view-state id="customerSearchStep" view="createSavingsAccountCustomerSearch" model="savingsAccountFormBean">
           <transition on="searchTermEntered" to="questionGroupStep" validate="true"></transition>
       </view-state>
   

   
   In this example, when event "searchTermEntered" is triggered, webflow will make a transition to "questionGroupStep" - our subflow.
   

Webflow unit test with subflow

1. Create a webflow unit test per usual.
2. In configureFlowBuilderContext(), create a stub subflow and register it with builder context:

   @Override
   protected void configureFlowBuilderContext(MockFlowBuilderContext builderContext) {
   
       ...
   
       // setup questionnaire subflow
       Flow questionnaire = new Flow("questionnaire");
       State start = new State(questionnaire, "selectQuestionnaire") {
           @Override
           protected void doEnter(RequestControlContext context)
                   throws FlowExecutionException {
               // empty
           }
       };
       questionnaire.setStartState(start);
       builderContext.registerSubflow(questionnaire);
   }
   

   
   In this example, a new (stub) Flow is instantiated with a name of "questionnaire". This is the name of the webflow you designated as subflow above. The flow will have a start state of "selectQuestionnaire".
   
   
3. When you verify the state, you will be using subflow's state.

       @Test
       public void testCustomerSearchStep_SearchTermEntered() {
   
           setCurrentState("customerSearchStep");
   
           MockExternalContext context = new MockExternalContext();
           context.setEventId("searchTermEntered");
           resumeFlow(context);
   
           assertCurrentStateEquals("selectQuestionnaire");
       }
   

   
   Note: you do not need to import webflow definition for the subflow. It is merely stubbed out because you are only testing the root webflow.