我有具有以下接口定义的 ac# WCF 服务：
[ServiceContract]
[ServiceKnownType(typeof(Exception))]
[ServiceKnownType(typeof(ArgumentException))]
[ServiceKnownType(typeof(ArgumentNullException))]
public interface IDataExchangeService
{
[OperationContract]
Exception DoSomething(bool someParam);
}
如您所见，该方法应该返回 NULL（当方法执行成功时）或包含任意错误消息的异常。该方法已使用 ServiceKnownType-attributes 声明，以避免在向客户端返回异常实例时出错。这仅在返回的异常类型等于声明的 ServiceKnownTypes 之一并且 InnerException 为 NULL 时才有效。但是，如果我返回一个异常，例如，将 ArgumentException 作为 InnerException，我会收到错误消息，指出 ArgumentException 类型未知：
There was an error while trying to serialize parameter http://tempuri.org/:DoSomething. The InnerException message was 'Type 'System.ArgumentNullException' with data contract name 'ArgumentNullException:http://schemas.datacontract.org/2004/07/System' is not expected. Consider using a DataContractResolver if you are using DataContractSerializer or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to the serializer.'.
我现在有两个问题：
- 我怎样才能使它可以返回任何类型的异常，而不必将每个可能的类型声明为 ServiceKnownType 属性？
- 是否可以返回具有任意 InnerException 类型的嵌套异常？