单项选择题 You are developing a Windows Communication Foundation (WCF) service that allows customers to update financial data. The client applications call the service in a transaction. 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 ... 10 class UpdateService : IDataUpdate 11 { 12 [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]13 public void Update(string accountNumber, double amount) 14 { 15 try 16 { 17 ... 18 } 19 catch(Exception ex) 20 { 21 WriteErrorLog(ex); 22 ... 23 } 24 } 25 } 26Customers report that the transaction completes successfully even if the Update method throws an exception.You need to ensure that the transaction is aborted if the Update method is not successful. What should you do? （）

单项选择题 You are developing a Windows Communication Foundation (WCF) service that must be discoverable.You need to ensure that the ServiceHost instance supports multiple discovery versions. What should you do?（）

单项选择题 You are developing a Windows Communication Foundation (WCF) service. You establish that the largest size of valid messages is 8,000 bytes. You notice that many malformed messages are being transmitted.Detailed information about whether each message is malformed must be logged.You need to ensure that this information is saved in XML format so that it can be easily analyzed. What should you add to the service configuration file?（）