暂停和继续工作流

工作流将暂停并恢复以响应书签和阻止活动（如 Delay），但也可使用持久性来显式暂停、卸载和恢复工作流。

暂停工作流

若要暂停工作流，请使用 Unload。 此方法请求保留和卸载工作流，并将在工作流未在 30 秒内卸载时引发 TimeoutException。

try  
{  
    // attempt to unload will fail if the workflow is idle within a NoPersistZone  
    application.Unload(TimeSpan.FromSeconds(5));  
}  
catch (TimeoutException e)  
{  
    Console.WriteLine(e.Message);  
}  

恢复工作流

若要恢复之前已暂停且已卸载的工作流，请使用 Load。 此方法会将工作流从持久性存储加载到内存中。

WorkflowApplication application = new WorkflowApplication(activity);  
application.InstanceStore = instanceStore;  
application.Load(id);  

示例

下面的代码示例演示如何使用持久性来暂停和恢复工作流。

static string bkName = "bkName";  
static void Main(string[] args)
{  
    StartAndUnloadInstance();  
}  
  
static void StartAndUnloadInstance()
{  
    AutoResetEvent waitHandler = new AutoResetEvent(false);  
    WorkflowApplication wfApp = new WorkflowApplication(GetDelayedWF());  
    SqlWorkflowInstanceStore instanceStore = SetupSqlpersistenceStore();  
    wfApp.InstanceStore = instanceStore;  
    wfApp.Extensions.Add(SetupMyFileTrackingParticipant);  
    wfApp.PersistableIdle = (e) => {          ///persists application state and remove it from memory
    return PersistableIdleAction.Unload;  
    };  
    wfApp.Unloaded = (e) => {  
        waitHandler.Set();  
    };  
    Guid id = wfApp.Id;  
    wfApp.Run();  
    waitHandler.WaitOne();  
    LoadAndCompleteInstance(id);  
}  
  
static void LoadAndCompleteInstance(Guid id)
{
    Console.WriteLine("Press <enter> to load the persisted workflow");  
    Console.ReadLine();  
    AutoResetEvent waitHandler = new AutoResetEvent(false);  
    WorkflowApplication wfApp = new WorkflowApplication(GetDelayedWF());  
    wfApp.InstanceStore =  
        new SqlWorkflowInstanceStore(ConfigurationManager.AppSettings["SqlWF4PersistenceConnectionString"].ToString());  
    wfApp.Completed = (workflowApplicationCompletedEventArgs) => {  
        Console.WriteLine("\nWorkflowApplication has Completed in the {0} state.",  
            workflowApplicationCompletedEventArgs.CompletionState);  
    };  
    wfApp.Unloaded = (workflowApplicationEventArgs) => {  
        Console.WriteLine("WorkflowApplication has Unloaded\n");  
        waitHandler.Set();  
    };  
    wfApp.Load(id);  
    wfApp.Run();  
    waitHandler.WaitOne();  
}  
  
public static Activity GetDelayedWF()
{  
    return new Sequence {  
        Activities ={  
            new WriteLine{Text="Workflow Started"},  
            new Delay{Duration=TimeSpan.FromSeconds(10)},  
            new WriteLine{Text="Workflow Ended"}  
        }  
    };  
}  
  
private static SqlWorkflowInstanceStore SetupSqlpersistenceStore()
{
     string connectionString = ConfigurationManager.AppSettings["SqlWF4PersistenceConnectionString"].ToString();  
    SqlWorkflowInstanceStore sqlWFInstanceStore = new SqlWorkflowInstanceStore(connectionString);  
    sqlWFInstanceStore.InstanceCompletionAction = InstanceCompletionAction.DeleteAll;  
    InstanceHandle handle = sqlWFInstanceStore.CreateInstanceHandle();  
    InstanceView view = sqlWFInstanceStore.Execute(handle, new CreateWorkflowOwnerCommand(), TimeSpan.FromSeconds(5));  
    handle.Free();  
    sqlWFInstanceStore.DefaultInstanceOwner = view.InstanceOwner;  
    return sqlWFInstanceStore;  
}