IErrorHandler.ProvideFault(Exception, MessageVersion, Message) Method
Definition
Important
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Enables the creation of a custom FaultException<TDetail> that is returned from an exception in the course of a service method.
public:
void ProvideFault(Exception ^ error, System::ServiceModel::Channels::MessageVersion ^ version, System::ServiceModel::Channels::Message ^ % fault);
public void ProvideFault (Exception error, System.ServiceModel.Channels.MessageVersion version, ref System.ServiceModel.Channels.Message fault);
abstract member ProvideFault : Exception * System.ServiceModel.Channels.MessageVersion * Message -> unit
Public Sub ProvideFault (error As Exception, version As MessageVersion, ByRef fault As Message)
Parameters
- version
- MessageVersion
The SOAP version of the message.
Examples
The following code example demonstrates a service that implements IErrorHandler that returns only FaultException<TDetail> of type GreetingFault
when a service method throws a managed exception.
#region IErrorHandler Members
public bool HandleError(Exception error)
{
Console.WriteLine("HandleError called.");
// Returning true indicates you performed your behavior.
return true;
}
// This is a trivial implementation that converts Exception to FaultException<GreetingFault>.
public void ProvideFault(
Exception error,
MessageVersion ver,
ref Message msg
)
{
Console.WriteLine("ProvideFault called. Converting Exception to GreetingFault....");
FaultException<GreetingFault> fe
= new FaultException<GreetingFault>(new GreetingFault(error.Message));
MessageFault fault = fe.CreateMessageFault();
msg = Message.CreateMessage(
ver,
fault,
"http://microsoft.wcf.documentation/ISampleService/SampleMethodGreetingFaultFault"
);
}
#endregion
#Region "IErrorHandler Members"
Public Function HandleError(ByVal [error] As Exception) As Boolean Implements IErrorHandler.HandleError
Console.WriteLine("HandleError called.")
' Returning true indicates you performed your behavior.
Return True
End Function
' This is a trivial implementation that converts Exception to FaultException<GreetingFault>.
Public Sub ProvideFault(ByVal [error] As Exception, ByVal ver As MessageVersion, ByRef msg As Message) Implements IErrorHandler.ProvideFault
Console.WriteLine("ProvideFault called. Converting Exception to GreetingFault....")
Dim fe As New FaultException(Of GreetingFault)(New GreetingFault([error].Message))
Dim fault As MessageFault = fe.CreateMessageFault()
msg = Message.CreateMessage(ver, fault, "http://microsoft.wcf.documentation/ISampleService/SampleMethodGreetingFaultFault")
End Sub
#End Region
The following code example shows how to use a service behavior to add the IErrorHandler implementation to the ErrorHandlers property.
// This behavior modifies no binding parameters.
#region IServiceBehavior Members
public void AddBindingParameters(
ServiceDescription description,
ServiceHostBase serviceHostBase,
System.Collections.ObjectModel.Collection<ServiceEndpoint> endpoints,
System.ServiceModel.Channels.BindingParameterCollection parameters
)
{
return;
}
// This behavior is an IErrorHandler implementation and
// must be applied to each ChannelDispatcher.
public void ApplyDispatchBehavior(ServiceDescription description, ServiceHostBase serviceHostBase)
{
Console.WriteLine("The EnforceGreetingFaultBehavior has been applied.");
foreach(ChannelDispatcher chanDisp in serviceHostBase.ChannelDispatchers)
{
chanDisp.ErrorHandlers.Add(this);
}
}
// This behavior requires that the contract have a SOAP fault with a detail type of GreetingFault.
public void Validate(ServiceDescription description, ServiceHostBase serviceHostBase)
{
Console.WriteLine("Validate is called.");
foreach (ServiceEndpoint se in description.Endpoints)
{
// Must not examine any metadata endpoint.
if (se.Contract.Name.Equals("IMetadataExchange")
&& se.Contract.Namespace.Equals("http://schemas.microsoft.com/2006/04/mex"))
continue;
foreach (OperationDescription opDesc in se.Contract.Operations)
{
if (opDesc.Faults.Count == 0)
throw new InvalidOperationException(String.Format(
"EnforceGreetingFaultBehavior requires a "
+ "FaultContractAttribute(typeof(GreetingFault)) in each operation contract. "
+ "The \"{0}\" operation contains no FaultContractAttribute.",
opDesc.Name)
);
bool gfExists = false;
foreach (FaultDescription fault in opDesc.Faults)
{
if (fault.DetailType.Equals(typeof(GreetingFault)))
{
gfExists = true;
continue;
}
}
if (gfExists == false)
{
throw new InvalidOperationException(
"EnforceGreetingFaultBehavior requires a FaultContractAttribute(typeof(GreetingFault)) in an operation contract."
);
}
}
}
}
#endregion
' This behavior modifies no binding parameters.
#Region "IServiceBehavior Members"
Public Sub AddBindingParameters(ByVal description As ServiceDescription, ByVal serviceHostBase As ServiceHostBase, ByVal endpoints As System.Collections.ObjectModel.Collection(Of ServiceEndpoint), ByVal parameters As System.ServiceModel.Channels.BindingParameterCollection) Implements IServiceBehavior.AddBindingParameters
Return
End Sub
' This behavior is an IErrorHandler implementation and
' must be applied to each ChannelDispatcher.
Public Sub ApplyDispatchBehavior(ByVal description As ServiceDescription, ByVal serviceHostBase As ServiceHostBase) Implements IServiceBehavior.ApplyDispatchBehavior
Console.WriteLine("The EnforceGreetingFaultBehavior has been applied.")
For Each chanDisp As ChannelDispatcher In serviceHostBase.ChannelDispatchers
chanDisp.ErrorHandlers.Add(Me)
Next chanDisp
End Sub
' This behavior requires that the contract have a SOAP fault with a detail type of GreetingFault.
Public Sub Validate(ByVal description As ServiceDescription, ByVal serviceHostBase As ServiceHostBase) Implements IServiceBehavior.Validate
Console.WriteLine("Validate is called.")
For Each se As ServiceEndpoint In description.Endpoints
' Must not examine any metadata endpoint.
If se.Contract.Name.Equals("IMetadataExchange") AndAlso se.Contract.Namespace.Equals("http://schemas.microsoft.com/2006/04/mex") Then
Continue For
End If
For Each opDesc As OperationDescription In se.Contract.Operations
If opDesc.Faults.Count = 0 Then
Throw New InvalidOperationException(String.Format("EnforceGreetingFaultBehavior requires a " & "FaultContractAttribute(typeof(GreetingFault)) in each operation contract. " & "The ""{0}"" operation contains no FaultContractAttribute.", opDesc.Name))
End If
Dim gfExists As Boolean = False
For Each fault As FaultDescription In opDesc.Faults
If fault.DetailType.Equals(GetType(GreetingFault)) Then
gfExists = True
Continue For
End If
Next fault
If gfExists = False Then
Throw New InvalidOperationException("EnforceGreetingFaultBehavior requires a FaultContractAttribute(typeof(GreetingFault)) in an operation contract.")
End If
Next opDesc
Next se
End Sub
#End Region
The following code example shows how to configure the service to load the service behavior using an application configuration file. For more details about how to expose a service behavior in a configuration file, see IServiceBehavior.
<configuration>
<system.serviceModel>
<services>
<service
name="Microsoft.WCF.Documentation.SampleService"
behaviorConfiguration="metaAndErrors">
<host>
<baseAddresses>
<add baseAddress="http://localhost:8080/SampleService"/>
</baseAddresses>
</host>
<endpoint
address=""
binding="wsHttpBinding"
contract="Microsoft.WCF.Documentation.ISampleService"
/>
<endpoint
address="mex"
binding="mexHttpBinding"
contract="IMetadataExchange"
/>
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="metaAndErrors">
<serviceDebug includeExceptionDetailInFaults="true"/>
<serviceMetadata httpGetEnabled="true"/>
<enforceGreetingFaults />
</behavior>
</serviceBehaviors>
</behaviors>
<extensions>
<behaviorExtensions>
<add
name="enforceGreetingFaults"
type="Microsoft.WCF.Documentation.EnforceGreetingFaultBehavior, HostApplication, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"
/>
</behaviorExtensions>
</extensions>
</system.serviceModel>
</configuration>
Remarks
Implement the ProvideFault method to create a custom fault message that is returned to the client. The ProvideFault method will always be called for exceptions that leave operations, except when the WCF runtime recognizes the exception as especially fatal and rethrows the exception itself. When all ProvideFault implementations have been called, the fault message is sent back to the client (if fault
is non-null
). If the fault
parameter is null
the default fault is sent to the client.
Note
The inbound message that caused the processing error is available during this method from the OperationContext.RequestContext property.
Note
Because the ProvideFault method can be called from many different places there are no guarantees made about which thread the method is called on. Do not depend on ProvideFault method being called on the operation thread.