Tempest: Soft state replication in the service tier

Soft state in the middle tier is key to enabling scalable and responsive three tier service architectures. While soft-state can be reconstructed upon failure, replicating it across multiple service instances is critical for rapid fail-over and high availability. Current techniques for storing and managing replicated soft state require mapping data structures to different abstractions such as database records, which can be difficult and introduce inefficiencies. Tempest is a system that provides programmers with data structures that look very similar to conventional Java Collections but are automatically replicated. We evaluate Tempest against alternatives such as in-memory databases and we show that Tempest does scale well in real world service architectures.