The EnSight client supports a gRPC based rpc system that makes it possible to access various aspects of the EnSight client in a service-orientated fashion. This functionality is enabled at EnSight launch via the -grpc_server {port} command line option
There is a raw gRPC interface accessed via the ensight.proto and ensight_fluent.proto files and a higher-level Python interface in the ensight_rpc module named ensight_grpc.py.