public class SetOwinRouteTemplateMessageHandler : DelegatingHandler
    {
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, 
CancellationToken cancellationToken)
        {
            var owinContext = request.GetOwinContext();
            if (owinContext == null) return base.SendAsync(request, cancellationToken);
            var routes = request.GetConfiguration().Routes;
            if (routes == null) return base.SendAsync(request, cancellationToken);
            var routeData = routes.GetRouteData(request);
            if (routeData == null) return base.SendAsync(request, cancellationToken);
            var subRoutes = routeData.Values["MS_SubRoutes"] as IHttpRouteData[];
            if (subRoutes == null) return base.SendAsync(request, cancellationToken);
            var routeTemplate = subRoutes[0].Route.RouteTemplate;
            owinContext.Environment.Add("metrics-net.routetemplate", routeTemplate);
            return base.SendAsync(request, cancellationToken);
        }
    }
   
    // Add the message handler to the HttpConfiguration
    httpconfig.MessageHandlers.Add(new SetOwinRouteTemplateMessageHandler());