gRPC is an alternative to REST for communications between a client and a server. The AuthZ created a client for Java that can be used to communicate with Kessel.

The client hasn't been merged yet in the upstream repo and is only available in a fork: https://github.com/merlante/insights-rebac/tree/RHCLOUD-32317-initial-java-client/relations-client-java

These additional resources about gRPC support in Quarkus may help:

• https://quarkus.io/guides/grpc-getting-started
• https://quarkus.io/guides/grpc