nmdb is a network database (dbm-style) for controlled networks that can use different protocols to to communicate with its clients. It supports TIPC, TCP, UDP and SCTP. It consists of an in-memory cache that saves (key, value) pairs, and a persistent backend that stores the pairs on disk. Both work combined, but the use of the backend is optional, so you can use the server only for cache queries, pretty much like memcached.