FaultContractAttribute Class

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class Service
{
    [OperationContract]
    // Define the fault contract for an operation.
    [FaultContract(typeof(ArithmeticFault))]
    public int Calculate(Operation op, int a, int b)
    {
        switch (op)
        {
            case Operation.Add:
                return a + b;
                break;

            case Operation.Subtract:
                return a - b;
                break;

            case Operation.Multiply:
                return a * b;
                break;

            case Operation.Divide:

                // Add support for faults
                try
                {
                    return a / b;
                }
                catch (DivideByZeroException e)
                {
                    ArithmeticFault fault = new ArithmeticFault();
                    fault.Operation = Operation.Divide;
                    fault.Description = e.Message;
                    throw new FaultException<ArithmeticFault>(fault);
                }

                break;
        }

        return 0;
    }
}

public enum Operation
{
    Add,
    Subtract,
    Multiply,
    Divide
}

public class ArithmeticFault
{
    public Operation Operation { get; set; }
    public string Description { get; set; }
}