NetManage Client Architecture
A NetManage client application writes to the NetManage API /Class Library (hereafter NMAPI) to query and modify the configuration of a switch. The NMAPI is implemented as shown in the figure. The NMAPI is essentially a wrapper that sits on a Adapter Layer. The purpose of the Adapter Layer is to detect requests that are directed at local switch silicon and route them directly to the local NM API Server. Requests that are intended for a remote switch are directed to the RPC Client Layer where they are ultimately XDR encoded (marshalled) into SunRPC protocol messages and sent on the network to a remote peer.
This approach avoids the SunRPC overhead for requests that are intended for the local switch silicon (localhost).
Referring back to the Server Side figure the localhost bypass implemented by the Adapter Layer corresponds to the Extensions API shown in that figure.
This is a very powerful abstraction that allows protocols, firewalls and other applications to be written without regard to where they may be run. A Server Extension can be written once and then deployed without modification as the performance requirements and hardware implementation require.