Before "distributed object computing" became widely accepted as an application
architecture, we worked on a framework for remote wireless clients
that exhibited many of the same properties as today's n-tier distributed applications:
Personal digital assistants (PDAs) are small handheld computers with
touch-sensitive screens that allow for pen-based input. While it is
possible to develop PDA applications with business logic, their limited
computing power lends them towards presentation applications for viewing
and gathering data, which is processed by a server that contains extensive
business logic to respond to business events.
Wireless networks of all types, even new digital ones,
provide a very restricted amount of
throughput when compared to conventional local area networks (LANs).
This places severe constraints on application architecture and
partitioning of functionality among the various tiers of a multitier
Due to the uncertainty of maintaining a connection, wireless clients
communicate with servers through well-defined transactions, where
the client submits a query or command and then waits for the result.
This same strategy is now being used for web-based applications in order
to provide scalability for many clients, where each client is involved
in a sequence of many brief connections, rather than holding onto one
open session for a long period of time.