Force WCF Host into Faulted State

Question

Is there a way to force a WCF Host to fault? (More specifically a REST based WCF Host.) Is there an Exception type that can be thrown that will cause the host to fault? If an exception can't get the host into a faulted state, what could?

In the "Api_Root" function below, I've thrown several different types of exceptions, and they either get caught by the exception handler, or cause the whole process to fail(OutOfMemoryException).

Some example code. Its in VB, but any C# help would also be greatly appreciated.

<ServiceContract(Name:="API", NameSpace:="urn:test")>
Public Interface IWebServiceApi

    <OperationContract()>
    <WebGet(UriTemplate:="GetObject")>
    Function Api_Root() As Object

End Interface

<ServiceBehavior(InstanceContextMode:=InstanceContextMode.PerCall, IncludeExceptionDetailInFaults:=True)>
Public Class WebServiceApi
    Implements IWebServiceApi

    Public Function Api_Root() As Object Implements IWebServiceApi.Api_Root

        //Throw Exception type that causes the Host to Fail

        Return New Object()
    End Function

End Class

Function StartService()

    _Service = New WebServiceHost(GetType(WebServiceApi), baseAddresses)

    _Service.Open()

    AddHandler _Service.Opened, AddressOf Me.Opened
    AddHandler _Service.Closed, AddressOf Me.Closed
    AddHandler _Service.Faulted, AddressOf Me.Faulted

End Function

Sub Faulted(sender As Object, e As EventArgs)

    //Handle the falted service here

End Sub

have you tried just throwing a fault exception? these links may be of interest: http://stackoverflow.com/questions/315736/how-do-i-prevent-a-wcf-service-from-enter-a-faulted-state and http://stackoverflow.com/questions/8181903/i-keep-getting-wcf-service-is-in-faulted-state-on-the-client-side-how-should-i — EdmundYeung99, Apr 28 '15 at 01:29
@EdmundYeung99 Throwing a `FaultException` or a class derived from it is the only way to **not** have your **client** go in to a faulted state. The OP *wants* his **host** connection to go in to faulted state. — Scott Chamberlain, Apr 28 '15 at 01:43

MatteoSp · Accepted Answer · 2015-04-28T08:20:05.170

4

The Failed state does not exist. But, if you are talking about a generic way to close the host you can try:

System.ServiceModel.OperationContext.Current.Host.Close();

If a failure is mandatory for you, than the state you're looking for is Faulted. The Host object (whose type is System.ServiceModel.Channels.CommunicationObject) has a method named Fault(), which isn't public, but you'll probably be able to call it with a bit of reflection. That should make the Host transitioning into the Faulted state.

UPDATE. You can also use a host derived from WebServiceHost:

class MyWebServiceHost : System.ServiceModel.Web.WebServiceHost
{
    public MyWebServiceHost(Type serviceType, params Uri[] baseAddresses)
    : base (serviceType, baseAddresses)
    {

    }

    public void Fail()
    {
        base.Fault();
    }
}

edited Apr 28 '15 at 08:20

answered Apr 27 '15 at 22:44

MatteoSp

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Yea, I meant the faulted state. If an exception can't get the host into a faulted state, what could? Any ideas? – Greg Apr 27 '15 at 23:36
Yes, the one I suggested. Did you try it? – MatteoSp Apr 28 '15 at 07:19
Had another one, probably simpler. I updated my answer – MatteoSp Apr 28 '15 at 08:20
this is THE solution. if you use System.ServiceModel.ServiceHost the same method is also offered so this is absolutely the way to go in order to test your connection fault handlers. – Chris Watts Oct 28 '16 at 09:13

Scott Chamberlain · Answer 2 · 2015-04-28T01:25:56.480

The only way to get a host in to the faulted state is if a exception occurs during the Open() call or the ChannelDispatcher that accepts the incoming connections throws an exception during the channel creation process as a user connects.

If you want to trigger it your self the easiest way I could find (After looking at the reference source a bit) is subscribe to the Opening event and throw a exception inside it. This will cause Open() to fail which will cause the connection to go into the faulted state.

Force WCF Host into Faulted State

2 Answers2

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