WorkflowApplicationUnhandledExceptionEventArgs.ExceptionSource Property

Definition

Namespace:

System.Activities

Assembly:

System.Activities.dll

Gets the activity that is the source of the unhandled exception.

public:
 property System::Activities::Activity ^ ExceptionSource { System::Activities::Activity ^ get(); };

public System.Activities.Activity ExceptionSource { get; }

member this.ExceptionSource : System.Activities.Activity

Public ReadOnly Property ExceptionSource As Activity

Property Value

Activity

An activity.

Examples

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;

    // Other choices are UnhandledExceptionAction.Abort and
    // UnhandledExceptionAction.Cancel
};

wfApp.Run();

Remarks

If an exception is thrown by an activity and is unhandled, the default behavior is to terminate the workflow instance. If an OnUnhandledException handler is present, it can override this default behavior. This handler gives the workflow host author an opportunity to provide the appropriate handling, such as custom logging, aborting the workflow, canceling the workflow, or terminating the workflow.