In this we see How ta handle exception in WCF using FaultContract Articles, samples and tutorials

In all managed applications, we handle the error using Exception Handling mechenism. In WCF applications, we does this by using SOAP FaultContract. SOAP faults are message types that are included in the metadata for a service operation and, therefore, create a fault contract that clients can use to make their operation more interactive. In addition, because SOAP faults are expressed to clients in XML form, they are highly interoperable.

Understanding WCF FaultContract
1. Create an empty solution named "WCF_ExceptionHandling".

2. Add a new project named "WCFService1" of type "WCF Service Library" in the solution.

3. Delete the file named "IService1.cs".

4. Delete all the code in the file named "Service1.cs".

5. Add the following code in the file named "Service1.cs".


[ServiceContract]
public interface IService1
{
[OperationContract]
string SomeMethod(int x);
}
public class CService1 : IService1
{
public string SomeMethod(int x)
{
if (x == 0)
{
throw new DivideByZeroException("CANNOT BE ZERO");
}
else if (x == 1)
{
throw new ArgumentException("CANNOT BE 1");
}
return "Method executed successfully with value: " +x.ToString();
}
}
public class WCFService1_HOST
{
static void Main()
{
ServiceHost h = new ServiceHost(typeof(CService1));
h.Open();
Console.WriteLine("Host started");
Console.ReadKey();
h.Close();
}
}

6. Delete all the markup inside the tag in the file named "App.config" .

7. Add the following markup inside .


< system.serviceModel>
<services>
<service name="WCFService1.CService1" behaviorConfiguration="PublishMetaData">
<host>
<baseAddresses>
<add baseAddress="http://localhost:9999/WCFService1"/>
</baseAddresses>
</host>
<endpoint address=""
binding="basicHttpBinding"
contract="WCFService1.IService1"/>
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="PublishMetaData">
<serviceMetadata httpGetEnabled="true" httpGetUrl="METADATA"/>
</behavior>
</serviceBehaviors>
</behaviors>
</system.serviceModel>

8. Change the output type of the above project to "Console Application".

9. Build the solution.

10. Add a new "Windows Forms Application" named "WCFService1_CLIENT" in the current solution.

11. Create the following UI

12. Start the host by pressing Ctrl + f5.

13. Add a Service Reference in the client application using the following URL
http://localhost:9999/WCFService1/METADATA?wsdl

14. Name the proxy as "MyProxy".

15. Add the following code inside the class of the form shown above


MyProxy.Service1Client proxy = new
WCFService1_CLIENT.MyProxy.Service1Client();

16. Add the following code in the Click event of the button


try
{
int x = int.Parse(textBox1.Text);
MessageBox.Show(proxy.SomeMethod(x));
}
catch (Exception ex)
{
MessageBox.Show("Exception type: "
+ ex.GetType().FullName + "\n" + ex.Message);
}

17. Configure the solution for multiple startup projects as follows
WCFService1 Start without debugging
WCFService1_CLIENT Start without debugging

18. Start without debugging. Enter 0 and 1 respectively in the textbox and click the button.
Observe the exception in each case.

19. Add the following markup inside the tag in the "App.config" file.

20. Start without debugging. Enter 0 and 1 respectively in the textbox and click the button.
Observe the exception in each case.

21. Remove the markup added in step 19 above.

22. In the "SomeMethod()" method in "Service1.cs" file, inside each condition, replace the existing code with the following code respectively.


DivideByZeroException ex = new DivideByZeroException("CANNOT BE ZERO");
throw new FaultException(ex,ex.Message);
ArgumentException ex = new ArgumentException("CANNOT BE 1");
throw new FaultException(ex,ex.Message);

23. Start without debugging. Enter 0 and 1 respectively in the textbox and click the button.
Observe the exception in each case.

24. Add the following attributes below [OperationContract] in the interface in "Service1.cs" file.


[FaultContract(typeof(DivideByZeroException))]
[FaultContract(typeof(ArgumentException))]
[FaultContract(typeof(MyException))]

25. Add another condition below the last condition inside the "SomeMethod()" method in "Service1.cs" file.


else if (x == 2)
{
IndexOutOfRangeException ex =
new IndexOutOfRangeException("CANNOT BE 2");
}

26. In the Click event of the button, replace the existing catch block with the following.


catch (System.ServiceModel.FaultException ex)
{
MessageBox.Show("Exception type: "
+ ex.GetType().FullName + "\n" + ex.Message);
}
catch (System.ServiceModel.FaultException ex)
{
MessageBox.Show("Exception type: "
+ ex.GetType().FullName + "\n" + ex.Message);
}
catch (System.ServiceModel.FaultException ex)
{
MessageBox.Show("Exception type: "
+ ex.GetType().FullName + "\n" + ex.Message);
}

27. Start without debugging. Enter 0, 1 and 2 respectively in the textbox and click the button. Observe the exception in each case.

28. Add the following class in the file "Service1.cs"


[DataContract]
public class MyException
{
string error;
string datetime;
public MyException(string error,string datetime)
{
this.error = error;
this.datetime = datetime;
}
public string TheError
{
get { return this.error; }
set { this.error = value; }
}
[DataMember]
public string ErrorTime
{
get { return this.datetime; }
set { this.datetime = value; }
}
}

29. Add another condition below the last condition inside the "SomeMethod()" method in "Service1.cs" file.


else if (x == 3)
{
MyException ex =
new MyException("Custom Exception Message",DateTime.Now.ToString());
throw new FaultException(ex, ex.TheError);
}

30. Add the following catch block before the last catch block in the Click event of the button.


catch (System.ServiceModel.FaultException ex)
{
MessageBox.Show("Exception type: " + ex.GetType().FullName + "\n" +
ex.Message +"\nGenerated at: " + ex.Detail.ErrorTime);
}

31. Start without debugging. Enter 0, 1, 2 and 3 respectively in the textbox and click the button. Observe the exception in each case.

In this we see How ta handle exception in WCF using FaultContract

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