With respect to the enablement of federated identity, Web services have advantages over traditional Web applications because Web services technologies natively support the externalization of subject authentication in a standard way. This is facilitated through dedicated security services provided by the infrastructure (WS-Trust STSs). However, when it comes to advanced identity federation use cases demanding more sophisticated federation features, Web services also suffer from a scattered technology landscape not easily accessible for non-experts. This landscape at least comprises WS-Federation, Liberty-Alliance ID-WSF, OASIS WSFED. This contribution investigates these Web services federation technologies. It uses a health- care use case that demands sophisticated features in identity federation to pinpoint their capabilities. Moreover, it considers the identity federation enablement features of common Web services stacks e.g. Apache Axis, Microsoft WCF and Sun Metro. This aims at providing a compass for those who are charged with architecting, designing and building identity federation solutions in Web services environments: Which technologies are out there? What are they good for? How are they supported in Web services stack?...
