Service that we develop might get error in come case. This error
should be reported to the client in proper manner. Basically when we
develop managed application or service, we will handle the exception
using try- catch block. But these exceptions handlings are technology
specific.
In order to support interoperability and client will also be interested only, what wents wrong? not on how and where cause the error.
By default when we throw any exception from service, it will not reach the client side. WCF provides the option to handle and convey the error message to client from service using SOAP Fault contract.
Suppose the service I consumed is not working in the client application. I want to know the real cause of the problem. How I can know the error? For this we are having Fault Contract. Fault Contract provides documented view for error accorded in the service to client. This help as to easy identity the what error has accord. Let us try to understand the concept using sample example.
Step 1: I have created simple calculator service with Add operation which will throw general exception as shown below
In order to support interoperability and client will also be interested only, what wents wrong? not on how and where cause the error.
By default when we throw any exception from service, it will not reach the client side. WCF provides the option to handle and convey the error message to client from service using SOAP Fault contract.
Suppose the service I consumed is not working in the client application. I want to know the real cause of the problem. How I can know the error? For this we are having Fault Contract. Fault Contract provides documented view for error accorded in the service to client. This help as to easy identity the what error has accord. Let us try to understand the concept using sample example.
Step 1: I have created simple calculator service with Add operation which will throw general exception as shown below
//Service interface
[ServiceContract()]
public interface ISimpleCalculator
{
[OperationContract()]
int Add(int num1, int num2);
}
//Service implementation
public class SimpleCalculator : ISimpleCalculator
{
public int Add(int num1, int num2)
{
//Do something
throw new Exception("Error while adding number");
}
}
try
{
MyCalculatorServiceProxy.MyCalculatorServiceProxy proxy
= new MyCalculatorServiceProxy.MyCalculatorServiceProxy();
Console.WriteLine("Client is running at " + DateTime.Now.ToString());
Console.WriteLine("Sum of two numbers... 5+5 =" + proxy.Add(5, 5));
Console.ReadLine();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.ReadLine();
}
public int Add(int num1, int num2)
{
//Do something
throw new FaultException("Error while adding number");
}
- Define a type using the data contract and specify the fields you want to return.
- Decorate the service operation with the FaultContract attribute and specify the type name.
- Raise the exception from the service by creating an instance and assigning properties of the custom exception.
[DataContract()]
public class CustomException
{
[DataMember()]
public string Title;
[DataMember()]
public string ExceptionMessage;
[DataMember()]
public string InnerException;
[DataMember()]
public string StackTrace;
}
[ServiceContract()]
public interface ISimpleCalculator
{
[OperationContract()]
[FaultContract(typeof(CustomException))]
int Add(int num1, int num2);
}
public int Add(int num1, int num2)
{
//Do something
CustomException ex = new CustomException();
ex.Title = "Error Funtion:Add()";
ex.ExceptionMessage = "Error occur while doing add function.";
ex.InnerException = "Inner exception message from serice";
ex.StackTrace = "Stack Trace message from service.";
throw new FaultException(ex,"Reason: Testing the Fault contract") ;
}
try
{
MyCalculatorServiceProxy.MyCalculatorServiceProxy proxy
= new MyCalculatorServiceProxy.MyCalculatorServiceProxy();
Console.WriteLine("Client is running at " + DateTime.Now.ToString());
Console.WriteLine("Sum of two numbers... 5+5 =" + proxy.Add(5, 5));
Console.ReadLine();
}
catch (FaultException<MyCalculatorService.CustomException> ex)
{
//Process the Exception
}
Figure 1: Bindings and Channel Stacks (draw new diagram)
