Our immediate need for Empire was to be able to build RDF-backed web apps, including Pelorus, while being compatible with JPA/Hibernate-style interfaces to RDBMS.
The primary design goal of Empire is to implement as much of the JPA API as possible so that it can drop into existing applications, providing a simple ORM layer for RDF.
The docs directory contains some information on Empire including some usage examples and a short roadmap of what we have planned for future versions.
Please also refer to the mailing list for help with Empire.
Empire is available under the Apache 2.0 License.