the data server’s workload. The separate
application logic layer also
relieves clients of complex processing
tasks. Because it can run on a minicomputer
that is much more powerful
than the typical client
workstations, the middle layer is
more efficient and cost-effective in
large-scale systems. Figure 10-17
shows where the data, the application
logic, and the user interface are
located on various architectures. In a
client/server system, the tiers communicate
using software called middleware,
which is described in the
following section.