Litelinks
A high-performance netty and thrift-based microservice RPC library for Java, supporting Zookeeper and etcd-based service discovery.
Litelinks was developed internally in IBM from early 2015 and mostly pre-dates public availability of gRPC. It is still used in some places within IBM, and has been open-sourced in 2021 because it's still a dependency of another newly open-sourced project. It is now mostly in maintenance mode.