Invariant: Shared state is strongly consistent across all nodes used by a service.
Invariant: Shared state is highly available and persistent (if desired). Need replicas for high availability.
Shared state in the form of hash tables (B-trees not discussed) and shared files.
Support for connection management where connections are grouped into partitions. Can exploit affinity by because connections of same partition go to the same node. Also differentiated quality-of-service in terms of how connections are mapped to partitions.