UnhandledExceptionAction Enumeration

.NET Framework (current version)
 

Specifies the action that occurs when an exception escapes the root of a workflow.

Namespace:   System.Activities
Assembly:  System.Activities (in System.Activities.dll)

public enum UnhandledExceptionAction

Member nameDescription
Abort

Specifies that the WorkflowApplication should abort the workflow.

Cancel

Specifies that the WorkflowApplication should schedule the cancellation of the root activity and resume execution.

Terminate

Specifies that the WorkflowApplication should schedule termination of the root activity and resume execution.

The OnUnhandledException function is invoked if an exception escapes the root of the workflow. The WorkflowApplicationUnhandledExceptionEventArgs provides access to the exception as well as a pointer to the Activity that generated the exception. Terminate is the default action if no OnUnhandledException handler is specified.

The following example invokes a workflow that throws an exception. The exception is unhandled by the workflow and the OnUnhandledException handler is invoked. The WorkflowApplicationUnhandledExceptionEventArgs are inspected to provide information about the exception, and the workflow is terminated.

Activity wf = new Sequence
{
    Activities =
     {
         new WriteLine
         {
             Text = "Starting the workflow."
         },
         new Throw
        {
            Exception = new InArgument<Exception>((env) => 
                new ApplicationException("Something unexpected happened."))
        },
        new WriteLine
         {
             Text = "Ending the workflow."
         }
     }
};

WorkflowApplication wfApp = new WorkflowApplication(wf);

wfApp.OnUnhandledException = delegate(WorkflowApplicationUnhandledExceptionEventArgs e)
{
    // Display the unhandled exception.
    Console.WriteLine("OnUnhandledException in Workflow {0}\n{1}",
        e.InstanceId, e.UnhandledException.Message);

    Console.WriteLine("ExceptionSource: {0} - {1}",
        e.ExceptionSource.DisplayName, e.ExceptionSourceInstanceId);

    // Instruct the runtime to terminate the workflow.
    return UnhandledExceptionAction.Terminate;
};

wfApp.Aborted = delegate(WorkflowApplicationAbortedEventArgs e)
{
    // Display the exception that caused the workflow
    // to abort.
    Console.WriteLine("Workflow {0} Aborted.", e.InstanceId);
    Console.WriteLine("Exception: {0}\n{1}",
        e.Reason.GetType().FullName,
        e.Reason.Message);
};

wfApp.Completed = delegate(WorkflowApplicationCompletedEventArgs e)
{
    if (e.CompletionState == ActivityInstanceState.Faulted)
    {
        Console.WriteLine("Workflow {0} Terminated.", e.InstanceId);
        Console.WriteLine("Exception: {0}\n{1}",
            e.TerminationException.GetType().FullName,
            e.TerminationException.Message);
    }
    else if (e.CompletionState == ActivityInstanceState.Canceled)
    {
        Console.WriteLine("Workflow {0} Canceled.", e.InstanceId);
    }
    else
    {
        Console.WriteLine("Workflow {0} Completed.", e.InstanceId);

        // Retrieve the outputs of the workflow.
        foreach (var kvp in e.Outputs)
        {
            Console.WriteLine("Name: {0} - Value {1}",
                kvp.Key, kvp.Value);
        }

        // Outputs can be directly accessed by argument name.
        // Console.WriteLine("The winner is {0}.", e.Outputs["Winner"]);
    }
};

wfApp.Run();

.NET Framework
Available since 4.0
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