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.
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?
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.
I have a WCF service defined, it accepts JSON and maps that JSON to an object at which point I can then begin debugging code.
Sometimes, the object fails to create. Most recently my service had a BodyStyle of Wrapped but should have been Bare. In this case I would have liked to watch the request come in and see what happens to it as it gets mapped from JSON to POCO and then onto the service so I can watch for errors.
I'd also like to see what happends with the response where I have also had issues in the past.
What is the best way of seeing what is going on in WCF when it is (kind of) out of my control? What kind of logging/tracing can I use and can I see errors/exceptions being thrown by WCF?
Thanks
Scott
I don't know much but svctraceviewer might help in case you haven't heard about it already.
Arnis gives a good suggestion. I'd also suggest using Fiddler to trace WCF traffic assuming you are using a HTTP end point. I've used fiddler to troubleshoot WCF issues so it might be helpful to you as well.
I've got some WCF services (hosted in IIS 6) which use the Enterprise Library (4.0) Validation Application Block. If a client submits a message which fails validation (i.e. gets thrown back in a ValidationFault exception), I'd quite like to be able to log the message XML somewhere (using code, no IIS logs). All the validation happens before the service implementation code kicks in.
I'm sure it's possible to set up some class to get run before the service implementation (presumably this is how the Validation Application Block works), but I can't remember how, or work out exactly what to search for.
Is it possible to create a class and associated configuration that will give me access to either the whole SOAP request message, or at least the message body?
Take a look at using the Policy Injection Application Block...
I'm currently developing an application in which I intercept (using PIAB) all requests incoming to the server and based on the type of request I apply different validation behavior using the VAB.
Here's an article about integrating PIAB with WCF:
http://msdn.microsoft.com/en-us/magazine/cc136759.aspx
You can create different inteception mechanisms such as attributes applied to exposed operations.
You could log the whole WCF Message:
http://msdn.microsoft.com/en-us/library/ms730064.aspx
Or you could combine it with Enterprise Library Logging Application Block.
I found a blog post which seems to do what I want - you create a class that implements IDispatchMessageInspector. In the AfterReceiveRequest method, you have access to the whole incoming message, so can log away. This occurs after authentication, so you also have access to the user name - handy for logging. You can create supporting classes that let you assign this behaviour to services via attributes and/or configuration.
IDispatchMessageInspector also gives you a BeforeSendReply method, so you could log (or alter) your response message.
Now when customers attempt to literally hand-craft SOAP request messages (not even using some kind of DOM object) to our services, we have easy-to-access proof that they are sending rubbish!
I have a VB.NET web service that calls a third party web service. How can I view the SOAP message generated by .NET before it is sent to the third party web service and how can I see the SOAP response before it is serialized by .NET.
When creating a standalone EXE, I see the Reference.vb file that is automatically generated, but don't see a similar file when my project is a web service. I have found lots of C# code to do this, but none in VB.NET.
Edit - Fiddler and TCP loggers are great, but will not work for my purposes. I need to be able to access the raw SOAP messages from within the application so I can log them or modify them. I need to do more than just see the messages going back and forth.
You can use fiddler or a tcp sniffer to filter and identify all outgoing and incoming traffic on your host.
This is if you want to see the xml request and response.
How about using an extension to allow you to examine the SOAP message?
Accessing Raw SOAP Messages in ASP.NET Web Services
http://msdn.microsoft.com/en-us/magazine/cc188761.aspx
I was trying to do the same thing and this seems to work for me:
Dim message As String = OperationContext.Current.RequestContext.RequestMessage.ToString()
I didn't think it would be that easy since most of the time ToString() returns the name of the class, but I tried it out and low and behold.
I know you asked this back in January so if since then you've figured out a better way let me know.
Please note that if you're catching the exception in a class that implements IErrorHandler then you have to perform this operation from within the ProvideFault() method instead of the HandleError() method because the context is closed before it gets to call the HandleError() method.
Hope this helps.