I want to log all exceptions (including serialization exception stack traces) in a WCF server to the Windows Event Log (log4net logging would also be acceptable).
What is the easiest way to do this?
Specifically all errors in serialization, in the service itself, etc. Right now I'm using tracing to get serialization errors during development. Tracing was the only way I could find out what object was actually have a problem with serialization. See Quickly finding WCF Serialization/Deserialization Issues for an example of getting the serialization stack trace.
I can handle errors in the service code itself. However, errors in the WCF machinery don't propagate to my service code (like serialization errors).
I don't need to send the errors to the client.
I just want to get the errors into one location (like the Event Log).
Right now (from my research) it appears that the IErrorHandler Interface with some custom code might be the best way to proceed. Will using the IErrorHandling interace catch the serialization exceptions?
Edit:
This may be the answer I'm looking for:
How do I create a global exception handler for a WCF Services?
I'd just like a confirmation that this will catch serialization errors and more importantly the details of those errors, also.
More Info:
How do I create a global exception handler for a WCF Services?
Yes, IErrorHandler will also catch serialization exceptions. You will get all information stored in the exception. Whether or not this enough detail for you, I can't say.
Note that there may be client-side errors (serialization and others) which will never make it to the server. You will not see those with the IErrorHandler.
Related
I have already developed my application, which has more than a 1000 functions. Now I need to implement fault contracts or exception handling in Silverlight without changing these functions.
Is there any common method that I can implement in one place in the WCF service layer and in one place in the Silverlight Application?
I want to implement this because when any exception occurs in the WCF layer, it will not send the real exception message to silverlight.
Silverlight only gets a message like this:
"Remote server not found..."
Real problem is i have already developed the system and now i need to implement the falultcontracts without changing too much or each function in Service layer.. so is there any method to create the falutcontract wrapper and place it over the WCF service Layer?
It's not 100% clear to me from the question what's going on in your case, but I can mention:
If you get an exception in Silverlight that the "Remote server not found..." then you won't get any exception details no matter what you do in the service (how can the service respond with those details, if the Silverlight app can not find the service?).
If you want to see exception details from the service in your app for debugging purposes, you can apply it to the entire service through the IncludeExceptionDetailInFaults property in the ServiceBehavior. This is considered a security risk (disclosing internal exception details) so it's not recommended for production.
As far as I know FaultContracts have to be set on the operations themselves, and you have to be explicit when you throw them.
PS. Your real problem may be that you have over a 1000 functions in your service, that doesn't seem healthy. On the other hand, if they are generated functions it may turn out to be a mixed blessing as you may be able to generate some fault code as well?
When a method is called on a WCF channel that has been disconnected for some reason, it raises an ObjectDisposedException.
Now is normal operation this should not happen, but if for some reason it did, I would like to be able to handle the exception nicely by showing an error to the user like "An operation failed because the service is not connected".
The problem is I just get a generic disposed exception in my appwide exception handler, so I have no way of determining whether WCF threw it.
to get around this I currently have a wrapper class that simply wraps all service method calls with try/catch and rethrows any ObjectDisposedException's as a custom comms exception that my global handler can deal with. this is a load of boilerplate stuff I could do without though.
Is there any way of determining whether WCF threw the exception?
Cheers
I used to encounter such problem, it seems it's difficult to determine whether the WCF throws exception. You can't use the CommunicationObject.Status for this problem, only when you try to use that channel, it throws exception to tell you that the channel is faulted.
Therefore, I used the way like yours.
I keep getting the 400 bad request if there is de-serialization issue / other errors. If i try to debug by setting a breakpoint in the method that gets called, it does not get hit, if there is a deserialization issue. How do I intercept this and tweak the response to give me more details.
I looked at some articles regarding webprotocolexception but I think the WCF Rest online Template and the starter kit or not the same. Is the starter kit like an add-on to the template?
thanks for your time.
Handling Exceptions in RESTful WCF Services is tough. Deserialization issues are the worst since no user code gets called. The framework handles the Exception and simply returns an error to the caller. There is a way to see those errors though. You have to configure tracing for WCF (via Web.config). Here’s a link describing the process as well as where to find the trace viewer on your machine:
Service Trace Viewer Tool (SvcTraceViewer.exe)
Unfortunately there's no way to tweak that behavior. For other Exceptions, though, you can implement a custom HttpBehavior (or HttpBehavior2 if you're using the REST Starter Kit) with a custom IErrorHandler implementation to handle the Exceptions.
Error 400 means bad request => it is picked up at WCF level and does not even reach the method. So you need to look at the request and if you are passing JSON, fast chance it is in wrong format.
I had a personal project that I implemented in WCF REST and had to battle with this error which was quite frustrating. Also error handling on the server and returning error codes to the client is atrocious since you cannot return text content and all I have is HTTP error code and error description (first line in the HTTP response). I will never ever use WCF REST again as it is a bodged implementation.
I have some WCF services with predefined FaultContract attributes. When the FaultException<TDetail> exceptions are thrown, they're sending StackTrace, Source and other potentially unsave information.
Is it possible to return only:
Detail (from the generic TDetail)
FaultMessage
FaultCode
(and possibly) FaultReason
Have you tried rolling your own fault exception using IErrorHandler? Also make sure in your app config file, the IncludeExceptionDetailInFaults attribute is set to false and, this might be helpful for best pratices.
One of 4 production servers once in a while generates tons of error claiming:
Method RunRules is not supported on this proxy, this can happen if the method is not marked with OperationContractAttribute or if the interface type is not marked with ServiceContractAttribute.
The method "RunRules" is one of the methods in wcf [ServiceContract] interface, and it is marked as [OperationContract].
Before this error, in the same method, occasionally it would get a wrong service through castle container. After I put more logging information to nail down exact cause, it mutated into the current error.
It is a webservice the error comes out of, it tries to call into a windows service through wcf endpoint when this happens. And this only happens on one specific machine. The frequency is about once a week or 2 weeks. Once recycle of the webservice happens (3 hours), the error stops.
To me it is almost like corrupted vtable. Just wondering, how would you approach this problem? Hate to ask IT people start to re-image the machine without solid proof.
Thanks!
No simple answer for such abstract magic error, so try out logging entire call stack, especially internal Castle DLL calls, if standart exception does not contain such deep call stack information - use reflection.
// use this in loop incrementing levelIndex up to st.FrameCount
// to grab all possible callstack entries
StackTrace st = new StackTrace();
st.GetFrame(levelIndex).GetMethod().Name;
Then using utility like ILSpy disassemble Castle DLL and try out analyze which state causes concrete execution flow which ends up with exception you got.
If you able log callstack - please share so I would be able check it as well.