Messaging clients that implement a browsable address book need a way to communicate with a data store that holds addressing data to access and manipulate that data. The NSPI Protocol enables communication between a messaging client and a data store.
The NSPI Protocol is a protocol layer that uses the remote procedure call (RPC) protocol as a transport, with a series of interface methods as specified in this document, that clients can use to communicate with an NSPI server.
The following diagram is a graphical representation of a typical communication sequence between a messaging client and an NSPI server.
Figure 1: NSPI Protocol message sequence