WorkflowRuntime.WorkflowUnloaded Event

Definition

Namespace:

System.Workflow.Runtime

Assembly:

System.Workflow.Runtime.dll

Occurs when the workflow instance is unloaded from memory.

public:
 event EventHandler<System::Workflow::Runtime::WorkflowEventArgs ^> ^ WorkflowUnloaded;

public event EventHandler<System.Workflow.Runtime.WorkflowEventArgs> WorkflowUnloaded;

member this.WorkflowUnloaded : EventHandler<System.Workflow.Runtime.WorkflowEventArgs> 

Public Event WorkflowUnloaded As EventHandler(Of WorkflowEventArgs) 

Event Type

EventHandler<WorkflowEventArgs>

Examples

The following code example demonstrates how to use WorkflowRuntime functionality from a workflow host. The code associates the WorkflowUnloaded with an event handler, a method named OnWorkflowUnload.

This code example is part of the Custom Persistence Service Sample.

static void Main()
{
    using (WorkflowRuntime workflowRuntime = new WorkflowRuntime())
    {
        try
        {
            // engine will unload workflow instance when it is idle
            workflowRuntime.AddService(new FilePersistenceService(true));

            workflowRuntime.WorkflowCreated += OnWorkflowCreated;
            workflowRuntime.WorkflowCompleted += OnWorkflowCompleted;
            workflowRuntime.WorkflowIdled += OnWorkflowIdle;
            workflowRuntime.WorkflowUnloaded += OnWorkflowUnload;
            workflowRuntime.WorkflowLoaded += OnWorkflowLoad;
            workflowRuntime.WorkflowTerminated += OnWorkflowTerminated;
            workflowRuntime.ServicesExceptionNotHandled += OnExceptionNotHandled;

            workflowRuntime.CreateWorkflow(typeof(PersistenceServiceWorkflow)).Start();

            waitHandle.WaitOne();
        }
        catch (Exception e)
        {
            Console.WriteLine("Exception \n\t Source: {0} \n\t Message: {1}", e.Source, e.Message);
        }
        finally
        {
            workflowRuntime.StopRuntime();
            Console.WriteLine("Workflow runtime stopped, program exiting... \n");
        }
    }
}

Shared Sub Main()

    Using currentWorkflowRuntime As New WorkflowRuntime()
        Try

            ' engine will unload workflow instance when it is idle
            currentWorkflowRuntime.AddService(New FilePersistenceService(True))

            AddHandler currentWorkflowRuntime.WorkflowCreated, AddressOf OnWorkflowCreated
            AddHandler currentWorkflowRuntime.WorkflowCompleted, AddressOf OnWorkflowCompleted
            AddHandler currentWorkflowRuntime.WorkflowIdled, AddressOf OnWorkflowIdled
            AddHandler currentWorkflowRuntime.WorkflowUnloaded, AddressOf OnWorkflowUnloaded
            AddHandler currentWorkflowRuntime.WorkflowLoaded, AddressOf OnWorkflowLoaded
            AddHandler currentWorkflowRuntime.WorkflowTerminated, AddressOf OnWorkflowTerminated
            AddHandler currentWorkflowRuntime.ServicesExceptionNotHandled, AddressOf OnExceptionNotHandled

            currentWorkflowRuntime.CreateWorkflow(GetType(PersistenceServiceWorkflow)).Start()

            waitHandle.WaitOne()

        Catch e As Exception
            Console.WriteLine("Exception \n\t Source: 0} \n\t Message: 1}", e.Source, e.Message)
        Finally
            currentWorkflowRuntime.StopRuntime()
            Console.WriteLine("Workflow runtime stopped, program exiting... \n")
        End Try
    End Using
End Sub

Remarks

A workflow instance can be unloaded from memory by an explicit call to Unload, or implicitly by the workflow run-time engine according to its own semantics. For example, the workflow run-time engine unloads a workflow instance if the instance becomes idle and the runtime has a WorkflowPersistenceService added for which UnloadOnIdle is true.

The workflow run-time engine raises the WorkflowUnloaded event after the state of the workflow instance has been successfully persisted but before the instance is invalidated in memory. Therefore, a WorkflowPersisted event precedes the WorkflowUnloaded event.

For the WorkflowUnloaded event, the sender contains the WorkflowRuntime and WorkflowEventArgs contains the WorkflowInstance associated with the event.

For more information about handling events, see Handling and raising events.