WCF REST Starter Kit Preview 2: System.NullReferenceException occurred in System.ServiceModel.Web.dll

Posted by jacobsrl on 10/5/2009 at 8:55 AM

It is difficult to say what might be causing this without more info or a project that can reproduce it. Can you give us more detail?

Posted by dead3y3 on 10/6/2009 at 2:11 AM

Hi, my colleague has found the issue. We have a partial Interface as contract. In this Interface we have the following method signature:
[OperationContract]
[WebGet(UriTemplate = "MessageFeed/{id}.Json")]
Stream GetMessageFeedJson(string id);

When this is comment out than the exception is gone. No idea what happened.

Posted by Microsoft on 10/6/2009 at 8:32 PM

Thank you for your feedback, We are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(http://support.microsoft.com/)

Posted by Microsoft on 10/9/2009 at 2:52 PM

Could you send the contract that you are using? We are particularly interested in the UriTemplates.

Posted by Microsoft on 10/9/2009 at 4:14 PM

Hi dead3y3,

Thanks for submitting this bug! This appears to be a bug in the REST Starter Kit code when it compares UriTemplate objects. The issue has been fixed and it will be part of a future release. As a workaround, reordering the methods in your contract should work. As a specific example, if you have a contract like the following:

    [ServiceContract]
    public interface IService1
    {
        [OperationContract]
        [WebGet]
        string SayHello(string name);

        [OperationContract]
        [WebGet(UriTemplate = "MessageFeed/{name}.Json")]
        string SayHello2(string name);

        [OperationContract]
        [WebGet(UriTemplate = "MessageFeed/{name}")]
        string SayHello3(string name);

    }

This will produce the exception like you're seeing. If you reorder the methods with UriTemplates above, it will work:

    [ServiceContract]
    public interface IService1
    {
        [OperationContract]
        [WebGet]
        string SayHello(string name);

        [OperationContract]
        [WebGet(UriTemplate = "MessageFeed/{name}")]
        string SayHello3(string name);

        [OperationContract]
        [WebGet(UriTemplate = "MessageFeed/{name}.Json")]
        string SayHello2(string name);

    }

If this does not help your scenario, feel free to reopen the bug and include the contract(s) you are using. You may also contact me directly at dmetzgar@microsoft.com.

Thank you,
Dustin Metzgar

Posted by dead3y3 on 10/12/2009 at 2:44 AM

Hi Dustin,

i tested your advice and it works !

Thanks for help

Posted by jdf22 on 10/15/2009 at 7:45 AM

Hello, W

We're suffering from the same issue from a service codebase that will run fine on a Vista Ultimate x64 machine, but will throw the NullReferenceException from System.UriTemplateCompoundPathSegment.IsEquivalentTo on an XP Professional SP3 machine. Both machines are running the latest .NET framework 3.5 SP1. I don't know if the OS in this case helps make the difference, I suspect not :-)

The code actually had to be reordered in the way you suggested above in order to get it working on the Vista machine. We thought we had the problem solved only to discover that the re-ordered code doesn't work around the problem on the XP machine. This makes relying on the code after it's been shipped a problem, since the usefulness of the workaround appears to be dependent on which machine the code is run on.

Please let us know what to do!

Best wishes,
jdf22

Is there a solution we can work on that will guarantee to run on any machine?