起飛 踏上.NET Framework 3.5開發之旅
新增Windows應用程式專案EquipmentApprove，介面如圖所示：
新增Workflow中的Sequential Workflow Library專案EquipmentApplyWorkflowLib
該流程包括三個外部方法Activities（CreateApply、ApproveApply、EscalateApply）和兩個外部事件Activities（EquipmentApprove、ApplyEscalated），一個ListenActivity用於等待外部事件來重新喚起流程。這裡頭有幾個關鍵的技術點：
（1）怎麼傳遞流程引數？啟動流程例項時把引數裝載到Dictionary中作為CreateWorkflow方法的引數傳遞：
// Fill the Parameters collection for this instance of the workflow
Dictionary
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();
獲取引數是在流程檔案中建立相同名稱的屬性，流程中就可以得到這些引數：
#region屬性
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）怎麼持久化流程？需要在初始化流程執行時的時候增加增加其久化服務：
// Add system SQL Persistenceservice
SqlWorkflowPersistenceService persistenceService = new SqlWorkflowPersistenceService(
"Initial Catalog=PersistenceStore;" +
"Data Source=localhost//SQLExpress; Integrated Security=SSPI");
wr.AddService(persistenceService);
還需要增加空閒時事件：
wr.WorkflowIdled += new EventHandler<WorkflowEventArgs>(wr_WorkflowIdled);
下面的程式碼表示在流程空閒時持久化（事實上是儲存到資料庫，也可以包括到檔案，你也可以隨時持久化流程）。
void wr_WorkflowIdled(object sender, WorkflowEventArgs e)
{
ThreadPool.QueueUserWorkItem(UnloadInstance, e.WorkflowInstance);
}
static void UnloadInstance(object workflowInstance)
{
((WorkflowInstance)workflowInstance).TryUnload();
}
（3）怎麼增加自定義的服務？需要增加服務介面和引數類：
[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]對於服務介面是必要的宣告，否則不能把服務增加到流程中。增加一個類實現這個介面：
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("裝置申請審批為空");
}
}
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("裝置申請呈送上級領導為空");
}
}
#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
}
在初始化流程執行時的時候就可以把服務增加進來：
// Add the external data service
ExternalDataExchangeService dataService = new ExternalDataExchangeService();
wr.AddService(dataService);
// Add custom EquipmentApply service
theApplyService = new EquipmentApplyService();
dataService.AddService(theApplyService);