Data centers constructed as clusters of inexpensive machines have compelling cost-performance benefits, but developing services to run on them can be challenging. This paper reports on a new framework, the Scalable Services Architecture (SSA), which helps developers develop scalable clustered applications. The work is focused on nontransactional high-performance applications; these are poorly supported in existing platforms. A primary goal was to keep the SSA as small and simple as possible. Key elements include a TCP-based "chain replication" mechanism and a gossip-based subsystem for managing configuration data and repairing inconsistencies after faults. Our experimental results confirm the effectiveness of the approach.