Spring Webflow - Prevent subflow being accessed directly - spring

Question

I'm using Spring Web Flow in my webapp and i would like to know if there is a general way to prevent some subflows to be accessed directly. These subflows are meant to be accessed just from certain flows, not directly by the url, so in these subflows i would like to check "if i was called from a flow".
is there any mechanisms to achieve it? I was looking at spring security but i couldn't find any useful feature to make this kind of restriction.
Thanks you!

Answer 1

You can check this by using input mapper attribute as shown below. Suppose you have a parent flow which invokes 'subflow-flow'. You need to pass an input value containing the name of the parent flow as:
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">
...
<subflow-state id="subflow-flow" subflow="subflow-flow">
<!--flowInitiatedBy should be different for each different parent flow-->
<input name="flowInitiatedBy" value="'parentFlowName'"/>
<transition on="invalidAccess" to="someViewWithMessage"/>
<transition on="processedSubflow" to="someOtherState"/>
</subflow-state>
...
</flow>
Then in subflow you can retrieve the parentflowname and perform the check in yourAction class. You can define subflow as:
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd"
start-state="start">
<input name="flowInitiatedBy" type="java.lang.String"/>
<action-state id="start">
<evaluate expression="yourAction.checkAccessibility(flowRequestContext)"/>
<transition on="invalidAccess" to="verifyWhetherDraftsExists"/>
<transition on="continue" to="continueToState"/>
</action-state>
<!--define other states for continue transition -->
...
<end-state id="invalidAccess"/>
<end-state id="processedSubflow"/>
</flow>
In your action class:
public class YourAction{
...
public String checkAccessibility(RequestContext context){
String flowInitiatedBy = context.getFlowScope().get("flowInitiatedBy");
//flowInitiatedBy will be empty if initiated by url.
if(flowInitiatedBy is empty){
return "invalidAccess";
}else{
// dosomething
return "continue";
}
}
...
}
Hope this helps.

Answer 2

I also wish there was some kind of built-in, simple mechanism. However, I just did this a slightly different way I thought I'd share. That is, since my Subflow knows its own name, I just had the first state in the Flow configuration check whether or not the Flow ID (name) matches that hardcoded name:
<decision-state id="subOnly">
<if test="flowExecutionContext.definition.id == 'thisSubflowFlowName'" then="invalidAccess" else="mySubflowFirstState"/>
</decision-state>
Where "invalidAccess" is an end-state like the prior answer shows.