NewClient returns a new SyncRPC client using given service registry If given registry is nil - use shared GW Service Registry config values.

grpc message is delivered as a length prefixed message within the HTTP2 DATA frames, with first 5 bytes for compression and msg length https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md.

Request - outstanding request.

SyncRpcClient opens a bidirectional connection with the cloud.