Microsoft Research continues to evolve its Gazelle concept. "In this paper, we present ServiceOS, a platform that tightly integrates a multi-principal browsing architecture with the underlying OS. ServiceOS provides a centralized, fine-grained resource access control model, and uses recursive web-oriented algorithms for sharing system resources. ServiceOS also introduces new abstractions that allow a web service to explicitly allocate and manage resources for any helper services they embed (e.g., via iframes). A key challenge that ServiceOS solves is managing resources in the face of complex web service composition."