多项选择题 You develop a Windows Communication Foundation (WCF) service that employees use to access bonus information.You define the following service contract. (Line numbers are included for reference only.) 01 [ServiceContract(SessionMode = SessionMode.Required)] 02 public interface IFinancialService 03 { 04 [OperationContract] 05 string Login(int employeeID, string passwordHash); 06 07 [OperationContract] 08 double GetBonus(int month); 09 10 [OperationContract(IsTerminating = true)] 11 void Logout(); 12 } Client application can invoke methods without logging in. You need to ensure that the client applications invoke Login before invoking any other method. You also need to ensure that client applications cannot consume the service after invoking Logout. Which two action should you perform? （）(Each correct answer presents part of the solution. Choose two.)。

单项选择题 You are developing a Windows Communication Foundation (WCF) service that is hosted by a Windows Forms Application.The ServiceHost instance is created in the Form Constructor.You need to ensure that the service is not blocked while the UI thread is busy. What should you do?（）

单项选择题 You are developing a Windows Communication Foundation (WCF) service that allows customers to update financial data. The service contract is defined as follows. (Line numbers are included for reference only) 01 [ServiceContract] 02 public interface IDataUpdate 03 { 04 [OperationContract] 05 [TransactionFlow(TransactionFlowOption.Mandatory)] 06 void Update(string accountNumber, double amount); 07 } 08 09 class UpdateService : IDataUpdate 10 { 11 [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = false)] 12 public void Update(string accountNumber, double amount) 13 { 14 ... 15 } 16 } 17 You need to ensure that the service is invoked within the transaction. What should you do?（）