如何在WCF中进行异常处理？

Question

I have some questions:

1. does it need to use try catch in all layers of wcf service
2. I have simple layered wcf service:

and define:

    [DataContract]
    public class ProductFault
    {
        public ProductFault(string msg)
        {
            FaultMessage = msg;
        }
        [DataMember]
        public string FaultMessage;
    }

and have:

       public Product GetProduct(int id)
       {
           ProductBDO productBDO = null;
           try
           {
               productBDO = productLogic.GetProduct(id);
           }
           catch (Exception e)
           {
               string msg = e.Message;
               string reason = "GetProduct Exception";
               throw new FaultException<ProductFault>
               (new ProductFault(msg), reason);
           }
           if (productBDO == null)
           {
               string msg =
               string.Format("No product found for id {0}",
               id);
               string reason = "GetProduct Empty Product";
               throw new FaultException<ProductFault>(new ProductFault(msg), reason);
           }

           Product product = new Product();//****
           TranslateProductBDOToProductDTO(productBDO,
           product);
           return product;
       }

when I pass invalid id to 'GetProduct' method I receive this error message:

How can I avoid raising error message in my service layer and send to client?

Answer 1

Do I need to use try catch in all layer of WCF service?

No - you should only handle exceptions when you can do something about it (handle it, log it, etc.)

How can avoid raising error message in my service layer and send to client?

What should you return if there is an exception? How else would you let the client know that something unexpected has happened? Returning null for "product not found" seems appropriate but if there is a deeper problem I would think you'd want that exception to bubble up (or at the least log it) and let the client know that something bad has happened. How much detail you want to allow to bubble up is up to you.