《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。