This is really lame. I'm creating a custom service host (That inherits from WebServiceHost) and I want to be able to programmatically add behaviors from configuration. Since the WebServiceHost is zero config there are no service elements to define a behavior config. Now I know I could manually create those service elements with an webHttpBinding and specify the behavior config, but I really do like the zero configuration feature, I just want to be able to define behaviors in config. Unfortunately the BehaviorExtensionElement's CreateBehavior is marked as internal. I'm not sure if M$ will make this public in the future or not but it looks like the only good way to get around it for now is with reflection (Or create a dummy service element with the behavior config, have the runtime load the behaviors and then copy them to your service, boo). I think in this instance reflection on an internal member is safe as that method has to be there in order for the behavior to be created by the runtime. I don't see how it can be changed since that would break custom behaviors. I snagged this simple extension method from the aforementioned thread, it uses reflection to invoke the internal CreateBehavior method.

public static object CreateBehavior(this BehaviorExtensionElement extensionElement)
{
    return extensionElement.GetType().
        GetMethod(
            "CreateBehavior",
            System.Reflection.BindingFlags.Instance |
            System.Reflection.BindingFlags.NonPublic).
                Invoke(extensionElement, new object[0] { });
}

I also whipped up a few ServiceHost extension methods that add the behaviors (Adapted from some reflected framework code):

public static void LoadBehaviors(
    this ServiceHost serviceHost,
    string behaviorConfiguration)
{
    ServiceBehaviorElement serviceBehaviors = 
        GetServiceBehaviorElement(serviceHost, behaviorConfiguration);
    if (serviceBehaviors != null)
    {
        foreach (BehaviorExtensionElement behaviorExtension in serviceBehaviors)
        {
            object extension = behaviorExtension.CreateBehavior();
            if (extension != null)
            {
                Type extensionType = extension.GetType();
                if (typeof(IServiceBehavior).IsAssignableFrom(extensionType))
                {
                    if (serviceHost.Description.Behaviors.Contains(extensionType))
                    {
                        serviceHost.Description.Behaviors.Remove(extensionType);
                    }
                    serviceHost.Description.Behaviors.Add((IServiceBehavior)extension);
                }
            }
        }
    }
}

public static ServiceBehaviorElement GetServiceBehaviorElement(
    this ServiceHost serviceHost, string behaviorConfiguration)
{
    BehaviorsSection behaviorsSection = 
        (BehaviorsSection)ConfigurationManager.
        GetSection("system.serviceModel/behaviors");
    foreach (ServiceBehaviorElement behavior in behaviorsSection.ServiceBehaviors)
    {
        if (behavior.Name == behaviorConfiguration)
            return behavior;
    }
    return null;
}

Then you simply run this on the ServiceHost:

serviceHost.LoadBehaviors("myBehaviorConfig");

Now if your creating your own service host you can override the ApplyConfiguration method and add them there. In the following example I add a check to see if there is a service element for this service. If not then I apply the behaviors, otherwise I skip it and assume that the service element has the desired configuration.

protected override void ApplyConfiguration()
{
    base.ApplyConfiguration();
    if (!this.HasServiceElement())
        this.LoadBehaviors("myBehaviorConfig");
}

The following is the HasServiceElement & supporting GetServiceElement ServiceHost extension methods:

public static bool HasServiceElement(this ServiceHost serviceHost)
{
    return (GetServiceElement(serviceHost) != null);
}

public static ServiceElement GetServiceElement(this ServiceHost serviceHost)
{
    ServicesSection servicesSection = (ServicesSection)ConfigurationManager.
        GetSection("system.serviceModel/services");
    ServiceElementCollection services = servicesSection.Services;
    foreach (ServiceElement element in services)
    {
        if (element.Name == serviceHost.Description.ConfigurationName)
            return element;
    }
    return null;
}