WCF中的异常处理

[ServiceContract(SessionMode = SessionMode.Allowed)] 
public interface IDocumentsExplorerService 
{ 
[OperationContract] 
DocumentList FetchDocuments(string homeDir); 
} 
[ServiceBehavior(InstanceContextMode=InstanceContextMode.Single)] 
public class DocumentsExplorerService : IDocumentsExplorerService,IDisposable 
{ 
public DocumentList FetchDocuments(string homeDir) 
{ 
//Some Codes 

if (Directory.Exists(homeDir)) 
{ 
//Fetch documents according to homedir 
} 
else 
{ 
throw new DirectoryNotFoundException( 
string.Format("Directory {0} is not found.",homeDir)); 
} 
} 
public void Dispose() 
{ 
Console.WriteLine("The service had been disposed."); 
} 
} 

catch (DirectoryNotFoundException ex) 
{ 
//handle the exception; 
}