How do you implement error handling in WCF (e.g., using FaultException)?

Question

ICSM Computer · Answer

In WCF, error handling is implemented primarily through the use of
FaultExceptionandlt;Tandgt; and service behaviors like IErrorHandler. This helps return
typed, user-friendly errors to clients instead of raw exceptions.
1. Using FaultExceptionandlt;Tandgt; for Typed Faults
Define a Fault Contract
[DataContract]
public class MyCustomFault
{
    [DataMember]
    public string ErrorMessage { get; set; }
    [DataMember]
    public string Details { get; set; }
}
Use [FaultContract] on Operations
[ServiceContract]
public interface IMyService
{
    [OperationContract]
    [FaultContract(typeof(MyCustomFault))]
    string GetData(int id);
}
Throw FaultExceptionandlt;Tandgt; from Service
public class MyService : IMyService
{
    public string GetData(int id)
    {
        if (id andlt; 0)
        {
            var fault = new MyCustomFault
            {
                ErrorMessage = "Invalid ID.",
                Details = "ID must be non-negative."
            };
            throw new FaultExceptionandlt;MyCustomFaultandgt;(fault, "Input validation failed.");
        }
        return $"Data for ID: {id}";
    }
}
2. Catching Faults on the Client Side
try
{
    var result = client.GetData(-1);
}
catch (FaultExceptionandlt;MyCustomFaultandgt; ex)
{
    Console.WriteLine("Service error: " + ex.Detail.ErrorMessage);
}
3. Unhandled Exceptions — Use IErrorHandler
For unhandled server exceptions, implement IErrorHandler to catch and convert them into fault messages:
public class GlobalErrorHandler : IErrorHandler
{
    public bool HandleError(Exception error)
    {
        // Logging logic here
        return true;
    }
    public void ProvideFault(Exception error, MessageVersion version, ref Message fault)
    {
        var customFault = new MyCustomFault
        {
            ErrorMessage = "Server Error",
            Details = error.Message
        };
        var faultException = new FaultExceptionandlt;MyCustomFaultandgt;(customFault);
        MessageFault msgFault = faultException.CreateMessageFault();
        fault = Message.CreateMessage(version, msgFault, faultException.Action);
    }
}
Hook into WCF via Behavior
public class ErrorBehavior : IServiceBehavior
{
    public void ApplyDispatchBehavior(ServiceDescription desc, ServiceHostBase host)
    {
        foreach (ChannelDispatcher dispatcher in host.ChannelDispatchers)
        {
            dispatcher.ErrorHandlers.Add(new GlobalErrorHandler());
        }
    }
    // Other required interface methods (empty)
}
And add it to your host:
serviceHost.Description.Behaviors.Add(new ErrorBehavior());
Summary
Technique
Purpose
FaultExceptionandlt;Tandgt;
Return typed, known faults
[FaultContract]
Declare fault types in WSDL
IErrorHandler
Catch and convert unhandled exceptions
FaultException (generic)
Send general error with message string

interview

How do you implement error handling in WCF (e.g., using FaultException)?

ICSM Computer

Can you answer this question?

1 Answers

1. Using `FaultException<T>` for Typed Faults

Define a Fault Contract

Use `[FaultContract]` on Operations

Throw `FaultException<T>` from Service

2. Catching Faults on the Client Side

3. Unhandled Exceptions — Use `IErrorHandler`

Hook into WCF via Behavior

Summary

Liked By

Technique	Purpose
`FaultException<T>`	Return typed, known faults
`[FaultContract]`	Declare fault types in WSDL
`IErrorHandler`	Catch and convert unhandled exceptions
`FaultException` (generic)	Send general error with message string

interview

How do you implement error handling in WCF (e.g., using FaultException)?

ICSM Computer

Can you answer this question?

1 Answers

1. Using FaultException<T> for Typed Faults

Define a Fault Contract

Use [FaultContract] on Operations

Throw FaultException<T> from Service

2. Catching Faults on the Client Side

3. Unhandled Exceptions — Use IErrorHandler

Hook into WCF via Behavior

Summary

Liked By

1. Using `FaultException<T>` for Typed Faults

Use `[FaultContract]` on Operations

Throw `FaultException<T>` from Service

3. Unhandled Exceptions — Use `IErrorHandler`