We've seen in the previous recipes how to use some common RPCs to query system state information on our JUNOS OS devices. But how exactly did we discover the cryptic connection between, for example, the CLI command show route and the RPC equivalent <get-route-information>? The JUNOS OS management daemon, mgd, is responsible for speaking the necessary native protocol to the type of client requesting information: either a human operator on the CLI, or a machine interface via XML. It maps the available system calls to both a CLI and an RPC. In this recipe, we'll explore this mapping.