Need recommendations and help with ASP.NET + WCF + Security

i'd like to recieve comments on the way i'm trying to build an asp.net web application which uses a WCF service that is hosted in another asp.net application. Both applications will live on the same machine, but the app with the WCF service will not be accessible from the outside. there will be two web servers sharing the load behind a load balancer.

The app pool of both applications will use the same local user account (web server is not part of a domain) and so i was thinking to use WsHttpBinding with windows security for communication between client and internal wcf service.

The fron-end asp.net app uses forms authentication through a custom membership/role provider to athenticate and authorize users. The user database is in a sql server database.

i need to somehow pass to the wcf service the user details (username + roles) so that in the wcf it will be possible to validate and authorize according to the roles of who is logged in the front-end. I read i need to use "support tokens", but i haven't figured out how to use this.

I read also something about claims and WIF, which seems interesting but have no idea how i could use these in my scenario.

is there anyone who can give me recommendations about the architecture and maybe also show me how to pass the username to the wcf service and also show me if possible to use claims based authorization?

First of all, if both servers are behind the corporate firewall on a corporate LAN, I would strongly suggest using netTcpBinding instead of any http based binding. NetTcpBinding is much faster due to encoding the message in a binary format.

As for username / password: your ASP.NET front-end server could set the client credentials for the user calling for the WCF service - after all, the ASP.NET servers do have access to the ASP.NET membership database, don't they?

Or if you cannot pass on the user's credentials, you could pass on some headers to your WCF service that would describe the user - actually, you probably only ever need the user's unique ID - since the WCF service could fish out the rest of the info from the ASP.NET user database again, if really needed.

As for claims - I don't think they'd be a good idea here - you don't really have to deal with a multitude of different authorization schemes, and you're not using any federation (e.g. allowing users from a different company or domain to use your services) - so those obvious benefits probably won't really be applicable to your case.