《WF in 24 Hours》读书笔记 - Hour 3(1) - Workflow：添加宿主和事件监听

1. 创建项目组，并添加一个Console Project和Activity Library，在Activity Library的项目中添加CodeActivity1和CodeActivity2，最终结构如下图所示：

2. CodeActivity1和2的代码如下：

     public sealed class CodeActivity1 : CodeActivity
     {
         // Define an activity input argument of type string
         public InArgument<string> Text { get; set; }

         // If your activity returns a value, derive from CodeActivity<TResult>
         // and return the value from the Execute method.
         protected override void Execute(CodeActivityContext context)
         {
             Console.WriteLine("before delay: \'{0}\'", DateTime.Now.ToLongTimeString());
         }
     }

     public sealed class CodeActivity2 : CodeActivity
     {
         // Define an activity input argument of type string
         public InArgument<string> Text { get; set; }

         // If your activity returns a value, derive from CodeActivity<TResult>
         // and return the value from the Execute method.
         protected override void Execute(CodeActivityContext context)
         {
             Console.WriteLine("after delay: \'{0}\'", DateTime.Now.ToLongTimeString());
         }
 }

3. 修改Activity1.xaml如下：

4. 修改Console Project的program.cs（注意，需要事先引入WorkflowsProject和System.Activities.dll）

         static void Main(string[] args)
         {
             AutoResetEvent syncEvent = new AutoResetEvent(false);

             Activity wf = new WorkflowsProject.Activity1();

             // Create the WorkflowApplication using the desired
             // workflow definition.
             WorkflowApplication wfApp = new WorkflowApplication(wf);

             // Handle the desired lifecycle events.
             wfApp.Completed = delegate(WorkflowApplicationCompletedEventArgs e)
             {
                 Console.WriteLine("Workflow {0} completed.", e.InstanceId.ToString());
                 syncEvent.Set();
             };

             wfApp.Aborted = delegate(WorkflowApplicationAbortedEventArgs e)
             {
                 Console.WriteLine("Workflow {0} terminated because {1}", e.InstanceId, e.Reason.Message);
                 syncEvent.Set();
             };

             // Start the workflow.
             wfApp.Run();

             // Wait for Completed to arrive and signal that
             // the workflow is complete.
             syncEvent.WaitOne();

             // Keep the console screen alive when workflow comnpletes
             Console.WriteLine("Press enter to continue");
             Console.Read();
         }

5. 运行。结果如下：

总结：通过此例，我们可以看到通过WorkflowApplication，我们可以在宿主程序中启动Workflow，并且捕捉Workflow的事件。