A client/server navigation system utilizes partial route guidance trees, enabling
a thin, mobile client to detect route deviation and provide alternate instructions
while awaiting response from a server. The system (10) consists of a server
(28) containing a network database and route-calculation program; a client
(26) capable of obtaining (12) its current location and destination,
displaying route instructions (22), and determining when it needs additional
instructions from the server (20,24); and communication (30,32,34,36)
between the client (26) and server (28). The invention allows for
long routes and responsive operation on a small, low-powered client despite lags
and lapses in communication.
