REEF was open sourced under Apache License 2 on January 21, 2014. This is joint work with Microsoft and UCLA. REEF stands for the Retainable Evaluator Execution Framework. The approach simplifies and unifies the lower layers of big data systems on modern resource managers like Apache YARN, Apache Mesos, and Google Omega. On these resource managers, REEF provides a centralized control plane abstraction that can be used to build a decentralized data plane for supporting big data systems, like those mentioned below. Special consideration is given to graph computation and machine learning applications, which require data retention on allocated resources, as they execute multiple passes over the data. For more details, refer to www.reef-project.org.