The USS SDK is a Java API to interface with the Foundation-hosted User Storage Service from an Eclipse workspace. The SDK handles login/authentication, session management and storage/retrieval of data.
The USS SDK was originally created by the Oomph project and released as USS SDK 1.0. The USS SDK was subsequently promoted as a full technology project. Version 1.1 deprecated the login/password ('session') based authentication mechanism in favour of a new OAuth-based approach supported by the Foundation. The session-based mechanism will be removed in USS SDK 2.0.
The USS SDK has documentation on the Eclipse Wiki.