单项选择题 You are consuming a Windows Communication Foundation (WCF) service in an ASP. NET Web application.The service interface is defined as follows:[ServiceContract]public interface ICatalog{ [OperationContract] [WebGet(UriTemplate="/Catalog/Items/{id}", ResponseFormat=WebMessageFormat.Json)] string RetrieveItemDescription(int id); } The service is hosted at Catalogsvc.You need to call the service using jQuery to retrieve the description of an item as indicated by a variable named itemId. Which code segment should you use?（）

单项选择题 A Windows Communication Foundation (WCF) service implements the following contract.(Line numbers are included for reference only.) 01 [ServiceContract] 02 public interface IDataAccessService 03 { 04 [OperationContract] 05 void PutMessage(string message); 06 ... 07 [OperationContract] 08 [FaultContract(typeof(TimeoutFaultException))] 09 [FaultContract(typeof(FaultException))] 10 string SearchMessages(string search); 11 } The implementation of the SearchMessages method throws TimeoutFaultException exceptions for database timeouts.The implementation of the SearchMessages method also throws an Exception for any other issue it encounters while processing the request.These exceptions are received on the client side as generic FaultException exceptions. You need to implement the error handling code for SearchMessages and create a new channel on the client only if the channel faults.What should you do?（）

单项选择题 A Windows Communication Foundation (WCF) solution exposes the following contract over an HTTP connection.[ServiceContract]public interface IDataService{ [OperationContract] string GetData();}Existing clients are making blocking calls to GetData. Calls to GetData take five seconds to complete.You need to allow new clients to issue non-blocking calls to get the data, without breaking any existing clients. What should you do?（）