EndPointBehaviour.cs

using System.ServiceModel.Description;

namespace RoyalMail
{
    public class EndPointBehaviour: IEndpointBehavior
    {
        RoyalMailHeaderCredentials _credentials;

        public void ApplyClientBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.ClientRuntime clientRuntime)
        {
            var inspector = new ClientMessageInspector();
 
            inspector.SetCredentials(_credentials);

            clientRuntime.MessageInspectors.Add(inspector);
        }
        
        public void SetCredentials(string clientId, string secret)
        {
            _credentials = new RoyalMailHeaderCredentials
            {
                ClientID = clientId,
                Secret = secret
            };
        }
        
        public void AddBindingParameters(ServiceEndpoint endpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters){}

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.EndpointDispatcher endpointDispatcher) {}

        public void Validate(ServiceEndpoint endpoint) {}
    }
}