WorkflowInstance.GetWorkflowQueueData Method

GetWorkflowQueueData returns a collection of WorkflowQueueInfo objects, each of which contains information about the state of one of the workflow queues associated with this workflow instance. WorkflowQueueInfo.Items contains the pending items for a WorkflowQueue and WorkflowQueueInfo.SubscribedActivityNames contains a list of the activities that are subscribed for item delivery on a WorkflowQueue.

The following code example demonstrates how you can use the GetWorkflowQueueData method to obtain information about the state of all workflow queues associated with a WorkflowInstance object. When the WorkflowIdled event occurs, the OnWorkflowIdled method defined in this example is called. It determines which workflow is idled using the WorkflowInstance property and then gets a collection of queued items for the workflow instance by calling the GetWorkflowQueueData method. The code iterates over the collection to determine which activity is waiting for the event that idled the workflow. It then sends an exception to the workflow queue using the EnqueueItem method along with the name of the event queue item.

This code example is part of the Canceling a Workflow SDK sample from the Program.cs file. For more information, see Canceling a Workflow.

static void OnWorkflowIdled(object sender, WorkflowEventArgs e)
{
    WorkflowInstance workflow = e.WorkflowInstance;

    Console.WriteLine("\n...waiting for 3 seconds... \n");
    Thread.Sleep(3000);

    // what activity is blocking the workflow
    ReadOnlyCollection<WorkflowQueueInfo> wqi = workflow.GetWorkflowQueueData();
    foreach (WorkflowQueueInfo q in wqi)
    {
        EventQueueName eq = q.QueueName as EventQueueName;
        if (eq != null)
        {
            // get activity that is waiting for event
            ReadOnlyCollection<string> blockedActivity = q.SubscribedActivityNames;
            Console.WriteLine("Host: Workflow is blocked on " + blockedActivity[0]);

            // this event is never going to arrive eg. employee left the company
            // lets send an exception to this queue
            // it will either be handled by exception handler that was modeled in workflow
            // or the runtime will unwind running compensation handlers and exit the workflow
            Console.WriteLine("Host: This event is not going to arrive");
            Console.WriteLine("Host: Cancel workflow with unhandled exception");
            workflow.EnqueueItem(q.QueueName, new Exception("ExitWorkflowException"), null, null);
        }
    }
}

.NET Framework

• Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

Other Resources