“All of Google’s services communicate using a Remote Procedure Call (RPC) infrastructure named Stubby; an open source version, gRPC, is available. 3 Often, an RPC call is made even when a call to a subroutine in the local program needs to be performed. This makes it easier to refactor the call into a different server if more modularity is needed, or when a server’s codebase grows. GSLB can load balance RPCs in the same way it load balances externally visible services.”