WCF 服务和客户端应用程序的错误处理

Question

In my case, I have a WCF Service (MyService.svc). I also have a client application that is instantiating and consuming the service contract.

What is the best way to handle exceptions at the service level and "transmit" them over to the client in an orderly and self-describing way?

If I have an unhandled exception on the WCF service, it seems as though that bubbles back to the client application as a CommunicationException.

But what's the best way to throw an exception at the service-level and have that same exception transmitted to the client-level? Or if I don't handle an exception at the service-level (or just re throw it at the service-level) how can that get explicitly directed to the client?

Or is that not typically how this SOA would work? What's the "right way" here?

Thanks!

Answer 1

First, if you want to pass the exception over the protocol, you have to wrap it in a faultexception, otherwise you will get a server error.

Use the FaultContract attribute over methods to enable faultContract and define the message you want to pass using creating a Message contract:

public interface IMyService
{
    [OperationContract]
    [FaultContract(typeof(Message))]
    void WCFOperation();
}

[DataContract(Namespace = "http://www.mycompany.pt/myservice")]
public class Message
{
    String _code;
    [DataMember]
    public String Code
    {
        get { return _code; }
        set { _code = value; }
    }

    String _text;
    [DataMember]
    public String Text
    {
        get { return _text; }
        set { _text = value; }
    }
}

To convert exceptions to FaultExceptions, i use the following helper:

    class Helper
    {

      internal static System.ServiceModel.FaultException<Message> ConvertToSoapFault(MyException ex)
      {
          FaultCode fc = new FaultCode(ex.Code);
          return new FaultException<Message>(new Message(){ Text= ex.Message, Code= ex.Code});
      }

      internal static System.ServiceModel.FaultException ConvertToSoapFault(Exception ex)
      {            
          return new FaultException(ex.Message);
      }
    }

Finally, at the operationContract implementation, simple do this:

    public void WCFOperation()
    {
        try
        {
           ...
        }           
        catch (Exception ex)
        {
            Helpers.publishError(ex);
            throw Helpers.ConvertToSoapFault(ex);
        }
    }