外部事件触发和处理：

1. 创建一个HandleExternalEventActivity

1     public class HandleEventActivity:HandleExternalEventActivity  2     {
      3         public HandleEventActivity()  4             : base()  5         {
      6             this.EventName = "HandleEvent";  7             this.InterfaceType = typeof(ITriggerEventService);  8             this.Name = "HandleEventActivity";  9         } 10 11     }

2. 创建一些类：

1     [ExternalDataExchange]  2     public interface ITriggerEventService  3     {
      4         void triggerEvent(Guid instanceId);  5  6         event EventHandler
      
        HandleEvent;  7     }  8  9     [Serializable] 10     public class TriggerEventArgs : ExternalDataEventArgs 11     {
     12         public TriggerEventArgs(Guid instanceId) 13             : base(instanceId) 14         { } 15     } 16 17     [Serializable] 18     public class TriggerEventService : ITriggerEventService 19     {
     20         #region ITriggerEventService Member 21 22         public void triggerEvent(Guid instanceId) 23         {
     24             TriggerEventArgs teArgs = new TriggerEventArgs(instanceId); 25             EventHandler
       
         evt = this.HandleEvent; 26             if (evt != null) 27             {
     28                 evt(this, teArgs); 29             } 30         } 31 32         public event EventHandler
        
          HandleEvent; 33 34         #endregion 35     }
        
       
      

3. 创建TriggerEventActivity：

创建一个custom activity. 里面放一个名叫callExternalMethodActivity的CallExternalMethodActivity。

1     [Designer(typeof(ActivityDesigner))]  2     public partial class TriggerEventActivity : SequenceActivity  3     {
      4         public TriggerEventActivity()  5         {
      6             InitializeComponent();  7         }  8  9         protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext) 10         {
     11             ExternalDataExchangeService edeService = executionContext.GetService(typeof(ExternalDataExchangeService)) as ExternalDataExchangeService; 12             if (edeService.GetService(typeof(TriggerEventService)) == null) 13             {
     14                 TriggerEventService teService = new TriggerEventService(); 15                 edeService.AddService(teService); 16             } 17             this.callExternalMethodActivity.ParameterBindings.GetItem("instanceId").Value = this.WorkflowInstanceId; 18             return base.Execute(executionContext); 19         } 20 21         public static DependencyProperty MethodInvokingEvent = DependencyProperty.Register("MethodInvoking", typeof(System.EventHandler), typeof(TriggerEventActivity)); 22 23         [DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Visible)] 24         [BrowsableAttribute(true)] 25         [CategoryAttribute("Execute Method")] 26         public event EventHandler MethodInvoking 27         {
     28             add 29             {
     30                 base.AddHandler(MethodInvokingEvent, value); 31             } 32             remove 33             {
     34                 base.RemoveHandler(MethodInvokingEvent, value); 35             } 36         } 37     }