Hi John

I'm not sure I quite understand what you are trying to do, but I think what you are saying is you MapUmbracoRoute rule is 'relative' and therefore is matched on all of the sites, which you might want to be the case, but you need to know when you associate the relevant Umbraco Node with the route - which site the incoming request is intended for?

In pure MVC you can create a DomainRoute for this kind of scenario: https://blog.maartenballiauw.be/post/2015/02/17/domain-routing-and-resolving-current-tenant-with-aspnet-mvc-6-aspnet-5.html but this won't work with MapUmbracoRoute as much as far as I can tell...

... Anyway one thing to be aware of is the UmbracoContext object that gets passed to your UmbracoVirtualNodeRouteHandler, and this contains a property containing the original request Url.

This will give you the domain of the request, and 'you could' use the Umbraco DomainService to find the root node id of the site corresponding to the requested domain, to give you your site context:

eg

int? rootContentId;
var ds = ApplicationContext.Current.Services.DomainService;
IDomain matchingDomain = ds.GetByName(domainName);
if (matchingDomain!=null){
 rootContentId = matchingDomain.RootContentId;
}

I say 'could' because the DomainService will make a SQL request, and that's likely to slow down your site if it occurs on every request, depending on the makeup of your multi-tenancy site and how often urls change, it may be more pragmatic, to just have a simple lookup dictionary here to map domain to umbraco id, eg if domain == "fish.com" then rootId is 22....

The other approach would be to map a specific relative route for each site eg:

      RouteTable.Routes.MapUmbracoRoute(
            "Product list by category for uk",
            "uk/category/{id}",
            new
            {
                controller = "Category",
                action = "ProductsByCategory",
                id = UrlParameter.Optional,
                page = 1,
                site = "UK",
            },
            new UmbracoYourVirtualNodeRouteHandler("UK"));
    }
      RouteTable.Routes.MapUmbracoRoute(
            "Product list by category for usa",
            "us/category/{id}",
            new
            {
                controller = "Category",
                action = "ProductsByCategory",
                id = UrlParameter.Optional,
                page = 1,
                site = "USA",
            },
            new UmbracoYourVirtualNodeRouteHandler("USA"));
    }

etc

anyway is that close to what you were asking, apologies if I've missed the gist!

regards

Marc