Exception Handling in node (v3.2)

[awolfard]

Hi all,

Playing around with some jbpm code and I have a question regarding exception handling in a node.

What I want is the following:

When an exception occurs in my actionhandler I want to startup a task so a user can correct the process(-step) manually and signal the process again.

I came with this:

Node actionhandlers all extend the BaseNodeHandler:

public abstract class BaseNodeHandler implements ActionHandler {

    public void execute(ExecutionContext executionContext) throws Exception {
        try {
            String returnValue = this.doExecute(executionContext);
            if (returnValue == null) {
                executionContext.leaveNode();
            } else {
                executionContext.leaveNode(returnValue);
            }
        } catch (Exception e) {
            // Start up another process with a task (async tasknode) to deal with this situation?
            // After manual correction give signal to continue processing?
        }
    }
   
    public abstract String doExecute(ExecutionContext executionContext) throws Exception;
}

When an exception occurs the node is not propagated (leaveNode is not called) and therefore the state of the process is persisted (right?)
. Then I want to start up another process which creates a task (async tasknode) so a user can make some corrections.

Is it okay to start another process in the exception block?

[kukeltje]

have a look here: http://www.infoq.com/articles/jBPM-user-interaction-patterns

[awolfard]

Hi Ronald,

Thank you for your response and the link you gave me.

But I think I am missing something because I cannot see how this link/page answers my question.

My main question is, is it valid to start a separate process in my catch block of the ActionHandler?

This new process has 1 task node (async) so a user can take some corrective action and later on signal the process to continue.

With kind regards,

Arnoud.

[kukeltje]

Sorry, the article was about escalation, not exception.

In the execute method a transaction is active, so I would not do long running things. If you want exceptions handled on a process level, I'd model those in the process as far as possible (since they have business consequences). What you could do is move set e.g. a processvariable with the name of that specific state, move the token to an 'exception handling task' and when finishing that task, move the token back to the original node.

[awolfard]

Hi Ronald,

Thanks for the reply.

I am aware that the execute is done in a transaction; that's the reason I have an async tasknode in the proces to be started.

I want to create a separate 'Generic Error Handling'-process for all processes; the exceptions I am talking about here are not Business Exceptions but real technical exceptions like 'Database is temporarly offline'.

That's why I do not want to model it in my proces.

Also if I model it in all my processes, I have to connect all nodes to the Generic Error Handling task.

Technically it is all working in my test environment but I wonder if Exception Handling like this is done before and if it feasable in production environments because I do not find much information about this topic (Exception Handling in JBPM) on the web.

Regards,

Arnoud.