Custom WCF service and custom behavior

Question

I often create WCF services that relies on out-of-the-box service factory (Microsoft.SharePoint.Client.Services.MultipleBaseAddressWebServiceHostFactory).

This is nice, because there's no web.config modification to apply.

However, is there any way to hook all requests?

For example, I would like to call SPUtility.ValidateFormDigest each time a service call is made.

Instead of duplicating the call to this method in each operation of my service, I'd like to add custom behavior. But I didn't found how to do that.

Any advise?

Answer 1

After some tests and issues, I finally discovered the correct way to reach my goal.

The idea is to attach a custom service behavior.

Here is the code of the behavior:

internal class ValidateSPFormDigestAttribute : Attribute, IServiceBehavior
{
    public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters)        {        }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase host)
    {
        foreach (ChannelDispatcher cDispatcher in host.ChannelDispatchers)
        {
            foreach (EndpointDispatcher eDispatcher in cDispatcher.Endpoints)
            {
                eDispatcher.DispatchRuntime.MessageInspectors.Add(new ValidateSPFormDigestInspector());
            }
        }
    }

    public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)        {        }
}

internal class ValidateSPFormDigestInspector : IDispatchMessageInspector
{
    public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
    {

        if (!SPUtility.ValidateFormDigest())
        {
            throw new FaultException(new FaultReason("Invalid form digest token"));
        }

        return null;
    }

    public void BeforeSendReply(ref Message reply, object correlationState)  {        }
}

Then I can simply attach my behavior using the attribute:

[BasicHttpBindingServiceMetadataExchangeEndpoint]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
[ValidateSPFormDigest]
public class MyService : IWidgetAdminService

The benefits is that it does not require a custom servicehost factory.