Retrieving parameter values using Microsoft Enterprise Library Exception Handler - .net-4.0

We are using Enterprise Library for all our logging and exception handling needs in our app. We have added an email listener to send all the caught exceptions in email to the administrator. One requirement is that when an exception occurs in a method we need to retrieve the parameter values of the method if any and attach it to the exception details in the email sent. Is it possible without writing a custom logger?

Just create a custom exception, setting the message to the parameters:
try {
...
} catch(Exception ex) {
var customException = new CustomException(ex, string.format("Param1 {0}, Param2 {1}", param1, param2));
bool rethrow = ExceptionPolicy.HandleException(customException, PolicyName);
}
verified that in fact the ExceptionFormatter class will indeed traverse all inner exceptions, so your CustomException could be as simple as
public class CustomException : Exception
{
public CustomException(string message, Exception innerException) : base(message, innerException)
{
}
}

Related

Apache Velocity.init() is throwing an exception

I am using Apache Velocity to create html pages but I am getting an exception while initializing.
Properties p = new Properties();
String path = EmpowERPlugin.getPluginDir()+IEIFileConstants.VELOCITY_PATH;
p.setProperty("resource.loader","file");
p.setProperty("file.resource.loader.path", path);
//p.setProperty ("runtime.log.logsystem.class","org.apache.velocity.runtime.log.NullLogSystem");
p.setProperty("class.resource.loader.class", "org.apache.velocity.runtime.resource.loader.FileResourceLoader");
try{
Velocity.init(p);
}catch(VelocityException e){
e.printStackTrace();
}catch(Exception e1){
e1.printStackTrace()
}finally{
//some code
}
while executing Velocity.init() the control directly goes to the finally block instead of catch, so I am not able to guess what type of exception it is
Exception class isn't catching all possible exceptions although its tricky name:
The class Exception and any subclasses that are not also subclasses of RuntimeException are checked exceptions.
I suggest in your case to catch the superclass Throwable:
The Throwable class is the superclass of all errors and exceptions in the Java language.

Camel Dead Letter Channel for all exceptions

Im creating a dead letter channel errorhandler like below
errorHandler(deadLetterChannel("direct:myDLC").useOriginalMessage().maximumRedeliveries(1));
from("direct:myDLC")
.bean(MyErrorProcessor.class);
The Bean MyErrorProcessor should be able to handle all types of checked and unchecked exceptions like below..
public void process(Exchange exchange) throws Exception {
Exception e=(Exception)exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class);
e.printStackTrace();
if(e instanceof MyUncheckedException){
logger.error("MyUncheckedException: "+((MyException) e).getErrorCode()+" : "+((MyException) e).getErrorDesc());
}else if(e instanceof MyException){
logger.error("MyException: "+((MyException) e).getErrorCode()+" : "+((MyException) e).getErrorDesc());
}
}
But after exception is handled the original message should be redirected to route's endpoint.. how to continue route once exception handled like this??
Using continued() will work, it will ignore the error and continue to process, so then you would probably want to handle the specific Exception
see http://camel.apache.org/exception-clause.html
onException(MyException.class)
.continued(true)
;
If you would use .useOriginalMessage() on this exception handling, the original message would be the message that is continued.

Lync Client API exception - Specified method is not supported

I am developing simple chat application using CWE which sends messages by using contextual data. I'm having "Specified method is not supported" exception message. This exception occurs when I try to start chat with group. one-to-one chat works fine with no exception. since I'm having same code on both sender & receiver side, I'm confused that how to make this work. Please help.
My code snippet as as follows.
void method1()
{
//
//here I have code to send an IM saying "lets chat in extension window"
//
try
{
Dictionary<ContextType, object> context = new Dictionary<ContextType, object>();
context.Add(ContextType.ApplicationId, "{1226271D-64C9-4F24-B416-E6A583F45A1C}");
context.Add(ContextType.ApplicationData, "initial_data_request");
try { IAsyncResult res = conversation.BeginSendInitialContext(context, null, null); }
catch (Exception e1)
{
MessageBox.Show(e1.Data+"\n\n"+e1.Message);
}
}
catch (Exception ee)
{
MessageBox.Show("Client Platform Exception: " + ee.Message);
}
}
This is the method I call when my application starts. It is supposed to send initial context so that receiver clients when receive this should open my extension application.
I found the answer. It is showing that exception because contextual data will not work in a group conversation.
Found the related thread here..
http://social.msdn.microsoft.com/Forums/lync/en-US/b4e46648-7097-4348-8327-6864f1c12ab2/contextdata-in-a-group-conversation?forum=communicatorsdk

How to prevent transaction scope from throwing an exception I have already handled?

I've got a WCF operation conceptually like this:
[OperationBehavior(TransactionScopeRequired = true)]
public void Foo()
{
try { DAL.Foo(); return Receipt.CreateSuccessReceipt(); }
catch (Exception ex) { return Receipt.CreateErrorReceipt(ex); }
}
If something goes wrong (say, foreign key constraint violaion) in executing the DAL code, control passes to the catch block as I'd expect. But when the method returns, it seems the transaction scope has sniffed out that the transaction failed, and it decides it better throw an exception to make sure to notify the caller about it.
In turn my client application does not get the receipt I want to return, but rather an exception:
System.ServiceModel.FaultException:
The transaction under which this method call was executing was asynchronously aborted.
What is wrong with my design?
I could have the service not catch anything, but this has it's own problems as the service needs to use exception shielding and the client (a batch tool internal to the system) needs to log the error information. The service logs errors too, but not in the same way and to the same place as the batch.
Be careful here! If you set TransactionAutoComplete=true then if the service returns normally the transaction will be committed. Only if there is an unhandled exception (which for the most part you don't have because you are catching exceptions and returning a receipt message) will the transaction be rolled back. See http://msdn.microsoft.com/en-us/library/system.servicemodel.operationbehaviorattribute.transactionautocomplete.aspx.
Think about a scenario where you successfully executed some DAL calls but some other exception (e.g. NullReferenceException) occurs. Now the transaction will be committed when the method completes because no unhandled exception has occurred but the client receives an ErrorReceipt.
For your scenario, I think you will have to manage the transactions yourself. For example:
[OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = false)]
public Receipt Foo()
{
// Create TransactionScope using the ambient transaction
using (var scope = new TransactionScope() )
{
try { DAL.Foo(); return Receipt.CreateSuccessReceipt(); scope.Complete(); }
catch (Exception ex) { return Receipt.CreateErrorReceipt(ex); }
}
}
You could eliminate boilerplate code by creating a helper method that wraps it all within the transaction or you could use policy injection/interception/aspects to manage transactions.
[OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = false)]
public Receipt Foo()
{
return ProcessWithTransaction(() =>
{
DAL.Foo();
return Receipt.CreateSuccessReceipt();
}
, (ex) =>
{
return Receipt.CreateErrorReceipt(ex);
}
);
}
T ProcessWithTransaction<T>(Func<T> processor, Func<Exception, T> exceptionHandler)
{
using (var scope = new TransactionScope())
{
try
{
T returnValue = processor();
scope.Complete();
return returnValue;
}
catch (Exception e)
{
return exceptionHandler(e);
}
}
}
You mention that you need to use exception shielding. If you are not averse to throwing faults when an error occurs then you could use Enterprise Library Exception Handling Block's exception shielding which also lets you log the information on the way out (if you desire).
If you decided to go that route your code would look something like this:
[OperationBehavior(TransactionScopeRequired = true)]
public void Foo()
{
// Resolve the default ExceptionManager object from the container.
ExceptionManager exManager = EnterpriseLibraryContainer.Current.GetInstance<ExceptionManager>();
exManager.Process(() =>
{
DAL.Foo();
return Receipt.CreateSuccessReceipt();
},
"ExceptionShielding");
}
Enterprise Library (via configuration) would then catch any exceptions and replace them with a new FaultException that is returned to the client.
[OperationBehavior(TransactionAutoComplete = true, TransactionScopeRequired = true)]
Presumably because the transaction is now rolled back as soon as the error occurs, rather than asynchronously when the scope goes out of scope :D, this behaves like I expected things to behave originally, and I can leave my design as it is.
(I had already written up the question when trying this occured to me. Hopefully posting it Q&A style will be more helpful than not posting the question at all.)

WP7: Unable to catch FaultException in asynchronous calls to WCF service

I am currently developing a Windows Phone 7 App that calls a WCF web service which I also control. The service offers an operation that returns the current user's account information when given a user's login name and password:
[ServiceContract]
public interface IWindowsPhoneService
{
[OperationContract]
[FaultContract(typeof(AuthenticationFault))]
WsAccountInfo GetAccountInfo(string iamLogin, string password);
}
Of course, there is always the possibility of an authentication failure and I want to convey that information to the WP7 app. I could simply return null in that case, but I would like to convey the reason why the authentication failed (i.e. login unknown, wrong password, account blocked, ...).
This is my implementation of the above operation (for testing purposes, all it does is throwing an exception):
public WsAccountInfo GetAccountInfo(string iamLogin, string password)
{
AuthenticationFault fault = new AuthenticationFault();
throw new FaultException<AuthenticationFault>(fault);
}
Now, if I call this operation in my WP7 app, like this:
Global.Proxy.GetAccountInfoCompleted += new EventHandler<RemoteService.GetAccountInfoCompletedEventArgs>(Proxy_GetAccountInfoCompleted);
Global.Proxy.GetAccountInfoAsync(txbLogin.Text, txbPassword.Password);
void Proxy_GetAccountInfoCompleted(object sender, RemoteService.GetAccountInfoCompletedEventArgs e)
{
if (e.Error != null)
{
MessageBox.Show(e.Error.Message);
return;
}
}
The debugger breaks in Reference.cs, saying that FaultException'1 was unhandled, here:
public PhoneApp.RemoteService.WsAccountInfo EndGetAccountInfo(System.IAsyncResult result) {
object[] _args = new object[0];
PhoneApp.RemoteService.WsAccountInfo _result = ((PhoneApp.RemoteService.WsAccountInfo)(base.EndInvoke("GetAccountInfo", _args, result)));
return _result;
}
BEGIN UPDATE 1
When pressing F5, the exception bubbles to:
public PhoneApp.RemoteService.WsAccountInfo Result {
get {
base.RaiseExceptionIfNecessary(); // <-- here
return ((PhoneApp.RemoteService.WsAccountInfo)(this.results[0]));
}
}
and then to:
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
if (System.Diagnostics.Debugger.IsAttached)
{
// An unhandled exception has occurred; break into the debugger
System.Diagnostics.Debugger.Break();
}
}
After that, the app terminates (with or without the debugger).
END UPDATE 1
Now, I would love to catch the exception in my code, but I am never given the chance, since my Completed handler is never reached.
Based on similar questions on this site, I have already tried the following:
Re-add the service reference --> no change
Re-create a really simple WCF service from scratch --> same problem
Start the app without the debugger to keep the app from breaking into the debugger --> well, it doesn't break, but the exception is not caught either, the app simply exits
Tell VS 2010 not to break on FaultExceptions (Debug > Options) --> does not have any effect
wrap every line in my app in try { ... } catch (FaultException) {} or even catch (Exception) --> never called.
BEGIN UPDATE 2
What I actually would like to achieve is one of the following:
ideally, reach GetAccountInfoCompleted(...) and be able to retrieve the exception via the GetAccountInfoCompletedEventArgs.Error property, or
be able to catch the exception via a try/catch clause
END UPDATE 2
I would be grateful for any advice that would help me resolve this issue.
The framework seems to read your WsAccountInfo.Result property.
This rethrows the exception on client side.
But you should be the first to read this property.
I don't know your AuthenticationFault class, does it have a DataContractAttribute and is it a known type like the example in
http://msdn.microsoft.com/en-us/library/system.servicemodel.faultcontractattribute.aspx ?
I believe I had the same problem. I resolved it by extending the proxy class and calling the private Begin.../End... methods within the Client object rather than using the public auto-generated methods on the Client object.
For more details, please see:
http://cbailiss.wordpress.com/2014/02/09/wcf-on-windows-phone-unable-to-catch-faultexception/