设备申请审批流程（WF实例）

 

这个例子在我们的项目中已经实际应用，所以我想叫做实例应该没什么问题。这是一个经典的设备申请审批流程，大家很多时候已经用其他的办法实现过了。本实例包括三个工程：EquipmentApply（设备申请exe）、EquipmentApprove（设备审批exe）、EquipmentApplyWorkflowLib（申请审批流程库dll)。首先新建Windows应用程序项目EquipmentApply，界面如图所示：

添加Windows应用程序项目EquipmentApprove，界面如图所示：

添加Workflow中的Sequential Workflow Library项目EquipmentApplyWorkflowLib，建立流程图：

该流程包括三个外部方法Activities（CreateApply、ApproveApply、EscalateApply）和两个外部事件Activities（EquipmentApprove、ApplyEscalated），一个ListenActivity用于等待外部事件来重新唤起流程。这里头有几个关键的技术点：

（1）       怎么传递流程参数？启动流程实例时把参数装载到Dictionary中作为CreateWorkflow方法的参数传递：

  // Fill the Parameters collection for this instance of the workflow

            Dictionary<string, object> parameters = new Dictionary<string, object>();

            parameters.Add("CreatedBy", txtCreatedBy.Text);

            parameters.Add("EquipmentName", txtName.Text);

            parameters.Add("Numbers",StrToInt(txtNumbers.Text));

            parameters.Add("Moneys", StrToFloat(txtMoneys.Text));

            parameters.Add("Desc", txtDesc.Text);

            

            // Get the type of the workflow

            Type type = typeof(EquipmentApplyWorkflowLib.EquipmentApplyWorkflow);

 

            // Start the workflow instance

            WorkflowInstance inst = theWorkflowRuntime.CreateWorkflow(type, parameters);

            inst.Start();

获取参数是在流程文件中建立相同名称的属性，流程中就可以得到这些参数：

        #region 属性

        private string m_EquipmentName = "";

        public string EquipmentName

        {

            get { return m_EquipmentName; }

            set { m_EquipmentName = value; }

        }

 

        private int m_Numbers = 0;

        public int Numbers

        {

            get { return m_Numbers; }

            set { m_Numbers = value; }

        }

 

        private float m_Moneys = 0;

        public float Moneys

        {

            get { return m_Moneys; }

            set { m_Moneys = value; }

        }

 

        private string m_Desc = "";

        public string Desc

        {

            get { return m_Desc; }

            set { m_Desc = value; }

        }

 

        private string m_CreatedBy = "";

        public string CreatedBy

        {

            get { return m_CreatedBy; }

            set { m_CreatedBy = value; }

        }

        #endregion

（2）       怎么持久化流程？需要在初始化流程运行时的时候增加增加其久化服务：

            // Add system SQL Persistence service

            SqlWorkflowPersistenceService persistenceService = new SqlWorkflowPersistenceService(

            "Initial Catalog=PersistenceStore;" +

            "Data Source=localhost//SQLExpress; Integrated Security=SSPI");

            wr.AddService(persistenceService);

还需要增加空闲时事件：

wr.WorkflowIdled += new EventHandler<WorkflowEventArgs>(wr_WorkflowIdled);

 

下面的代码表示在流程空闲时持久化（事实上是保存到数据库，也可以包括到文件，你也可以随时持久化流程）。

void wr_WorkflowIdled(object sender, WorkflowEventArgs e)

        {

            ThreadPool.QueueUserWorkItem(UnloadInstance, e.WorkflowInstance);

        }

static void UnloadInstance(object workflowInstance)

        {

            ((WorkflowInstance)workflowInstance).TryUnload();

        }

（3）       怎么增加自定义的服务？需要增加服务接口和参数类：

    [Serializable]

    public class EquipmentApplyEventArgs : ExternalDataEventArgs

    {

        private string _operatorName;

 

 

        public EquipmentApplyEventArgs(Guid InstanceID, string operatorName)

            : base(InstanceID)

        {

            _operatorName = operatorName;

        }

 

        public string OperatorName

        {

            get { return _operatorName; }

            set { _operatorName = value; }

        }

    }

 

    [ExternalDataExchange]

    public interface IEquipmentApplyService

    {

        event EventHandler<EquipmentApplyEventArgs> EquipmentApplyApproved;

        event EventHandler<EquipmentApplyEventArgs> EquipmentApplyEscalated;

 

        void CreateEquipmentApply(string name, int numbers, float moneys, string description, string createdBy);

 

        void ApproveEquipmentApply(Guid applyID);

        void EscalateEquipmentApply(Guid applyID);

    }

[ExternalDataExchange]对于服务接口是必要的声明，否则不能把服务增加到流程中。增加一个类实现这个接口：

     public class EquipmentApplyService: IEquipmentApplyService

     {

        // Implement events

        public event EventHandler<EquipmentApplyEventArgs> EquipmentApplyApproved;

        public event EventHandler<EquipmentApplyEventArgs> EquipmentApplyEscalated;

 

        public void RaiseApproveEquipmentApplyEvent(Guid instanceId)

        {

            // Raise the event to the workflow

            ThreadPool.QueueUserWorkItem(JustApproveTheEquipmentApply,

                new EquipmentApplyEventArgs(instanceId, "ljc"));

        }

 

        public void JustApproveTheEquipmentApply(object o)

        {

            EquipmentApplyEventArgs args = o as EquipmentApplyEventArgs;

 

            if (EquipmentApplyApproved != null)

                EquipmentApplyApproved(null, args);

            else

            {

                System.Windows.Forms.MessageBox.Show("设备申请审批为空");

            }

        }

 

        public void RaiseEscalateEquipmentApplyEvent(Guid instanceId)

        {

            // Raise the event to the workflow

            ThreadPool.QueueUserWorkItem(JustEscalateTheEquipmentApply,

                new EquipmentApplyEventArgs(instanceId, "ljc"));

        }

 

        public void JustEscalateTheEquipmentApply(object o)

        {

            EquipmentApplyEventArgs args = o as EquipmentApplyEventArgs;

 

            if (EquipmentApplyEscalated != null)

                EquipmentApplyEscalated(null, args);

            else

            {

                System.Windows.Forms.MessageBox.Show("设备申请呈送上级领导为空");

            }

        }

 

 

        #region IEquipmentApplyService

        void IEquipmentApplyService.CreateEquipmentApply(string name, int numbers, float moneys, string description, string createdBy)

        {

            // Fill up a EquipmentApply: same ID as the workflow

            string applyID = WorkflowEnvironment.WorkflowInstanceId.ToString();

 

            // Create EquipmentApply on the DB

            EquipmentApplyRule.CreateEquipmentApply(applyID,name,numbers,moneys, description, createdBy);

        }

 

        void IEquipmentApplyService.ApproveEquipmentApply(Guid applyID)

        {

            // Update EquipmentApply on the DB

            EquipmentApplyRule.UpdateEquipmentApply(WorkflowEnvironment.WorkflowInstanceId.ToString(), EquipmentApplyStatus.Approved);

        }

 

        void IEquipmentApplyService.EscalateEquipmentApply(Guid applyID)

        {

            // Update EquipmentApply on the DB

            EquipmentApplyRule.UpdateEquipmentApply(WorkflowEnvironment.WorkflowInstanceId.ToString(), EquipmentApplyStatus.Escalated);

        }

        #endregion

     }

在初始化流程运行时的时候就可以把服务增加进来：

        // Add the external data service

        ExternalDataExchangeService dataService = new ExternalDataExchangeService();

        wr.AddService(dataService);

 

        // Add custom EquipmentApply service

        theApplyService = new EquipmentApplyService();

        dataService.AddService(theApplyService);