RPATA (PATA is Swahili for 'find') is a minimalist, highly configurable, multicast-based peer discovery service library. It has been designed to be used as a complement to existing networking libraries such as ZMQ. No assumptions have been made on the messaging paradigm in use and it can therefore be used with well known ones such as PUBLISH-SUBSCRIBE, PUSH-PULL, ACTOR framework or any others that may benefit from having an automated peer discovery service.
Also if the only reason for using DDS/RTPS is because of its in-built discovery service, then RPATA + your favourite networking library could be a better alternative.
RPATA is still under heavy development and things are bound to change. Contributions and pull requests are welcome!