如何在CSLA框架中,使用状态机工作流

最近的一个项目里，使用了CSLA框架。CSLA有一个基本的设计原理，就是充分利用数据代理（同时规定BussinessObject is serializable），这个代理保证了csla的5层构架对各种物理部署构架的适应性。从它的框架可以看见，它的数据操作都是在DataPotol中定义，所以我们如果要在csla中使用工作流，切不可违反它的这一规定。

 

DataPortalClient.IDataPortalProxy proxy;
     proxy = GetDataPortalProxy(method.RunLocal);

 

普通的WebApplication的做法是在globel文件里加载工作流，如下所示：

protected void Application_Start(object sender, EventArgs e)
      {
          WorkflowRuntime workflowRuntime = new WorkflowRuntime(ConfigurationParameters.WorkflowName);
          workflowRuntime.AddService(new SqlWorkflowPersistenceService(ConfigurationParameters.WorkflowDBConn));
          workflowRuntime.AddService(new SqlTrackingService(ConfigurationParameters.WorkflowDBConn));
          ExternalDataExchangeService dataService = new ExternalDataExchangeService();
          workflowRuntime.AddService(dataService);
          WorkflowServices service = new WorkflowServices();
          dataService.AddService(service);
          workflowRuntime.StartRuntime();
          Application[ConfigurationParameters.WorkflowName] = workflowRuntime;
      }

在CSLA框架里，我们这样做：建立一个Command对象：

  [Serializable]
    public class WorkflowCommand : CommandBase
    {
        private static WorkflowRuntime m_workflowRuntime;
        private static ExternalDataExchangeService m_exchangeService;
        private static bool m_unloadFlag = false;
        public static WorkflowService WorkflowServiceInstance { get; private set; }
        public WorkflowInstance WorkflowInstance { get; private set; }

        public static WorkflowRuntime WorkflowRuntime
        {
            get { return WorkflowCommand.m_workflowRuntime; }
        }

        #region Factory Methods


        public static void InitializeWorkflowRuntime()
        {
            m_unloadFlag = false;
            WorkflowCommand cmd = new WorkflowCommand();
            DataPortal.Execute<WorkflowCommand>(cmd);
        }

        public static void UnloadWorkflowRuntime()
        {
            m_unloadFlag = true;
            WorkflowCommand cmd = new WorkflowCommand();
            DataPortal.Execute<WorkflowCommand>(cmd);
        }

        #endregion

        #region Server-side Code

        protected override void DataPortal_Execute()
        {
            if (!m_unloadFlag)
            {
                m_workflowRuntime = new WorkflowRuntime();
                m_exchangeService = new ExternalDataExchangeService();
                m_workflowRuntime.AddService(new ManualWorkflowSchedulerService());
                m_workflowRuntime.AddService(m_exchangeService);
                m_workflowRuntime.AddService(new SqlWorkflowPersistenceService(ConfigrationParameters.WorkflowConn));
                m_workflowRuntime.AddService(new SqlTrackingService(ConfigrationParameters.WorkflowConn));

                WorkflowServiceInstance = new WorkflowServiceInstance();
                m_exchangeService.AddService(WorkflowServiceInstance);

                m_workflowRuntime.StartRuntime();
            }
            else if (m_workflowRuntime != null)
            {
                m_workflowRuntime.StopRuntime();
            }
        }

        #endregion

然后在globel里加载：

protected void Application_Start(object sender, EventArgs e)
     {
         WorkflowCommand.InitializeWorkflowRuntime();
     }

这样的方式，保证了工作流的初始化在服务端完成，充分体现CSLA的思想。

 

那么如何在Bussiness object里使用这个Command对象呢，我们需要在Bussiness Object的DataPotal里控制工作流的流动和可持续化的操作，比如：

 

 protected override void DataPortal_Update()
        {
            WorkflowInstance wfInstance = null;
            ManualWorkflowSchedulerService schec = null;
            WorkflowServiceInstance service = null;
            Guid workflowID = Guid.Empty;

            if (isrunWorkflow)
            {
                workflowID = ReadProperty(WorkflowIdProperty);
                wfInstance = WorkflowCommand.WorkflowRuntime.GetWorkflow(workflowID);
                wfInstance.Load();
                schec = WorkflowCommand.WorkflowRuntime.GetService<ManualWorkflowSchedulerService>();
                service = WorkflowCommand.WorkflowRuntime.WorkflowServiceInstance;          
                service.Start(Id, workflowID);
                schec.RunWorkflow(workflowID);
            }

            //TODO:其他数据操作

            wfInstance.Unload();
        }
    }

 

Ok，如上所示，把BussinessObject的数据操作和工作流数据操作都封装进DataPortal方法里，这样保证了工作流可持续化及跟踪服务在服务端运行。

这样，工作流就嵌入到CSLA框架中。

 

在界面，我们需要进入2层的innerException来捕捉工作流的异常：

catch (Exception ex)
{
	if (ex.InnerException.InnerException is System.Workflow.Activities.EventDeliveryFailedException)
	{
		//alert("not allowed!")
		return;
	}
	else	{	}	
}

 

整个过程结束。