Sommerville-Software-Engineering-10ed

508 Chapter 17 ■ Distributed software engineering
Database 1
Integrator 1
Report gen.
Database 2
Visualizer
Integrator 2
Database 3
Display
Figure 17.13 A
distributed component
architecture for a
data-mining system
Clients
4. It is possible to reconfigure the system dynamically with components migrating across
the network as required. This may be important where there are fluctuating patterns
of demand on services. A service-providing component can migrate to the same
processor as service-requesting objects, thus improving the performance of the system.
A distributed component architecture can be used as a logical model that allows
you to structure and organize the system. In this case, you think about how to provide
application functionality solely in terms of services and combinations of services.
You then work out how to implement these services. For example, a retail
application may have application components concerned with stock control, customer
communications, goods ordering, and so on.
Data-mining systems are a good example of a type of system that can be implemented
using a distributed component architecture. Data-mining systems look for
relationships between the data that may be distributed across databases (Figure 17.13).
These systems pull in information from several separate databases, carry out computationally
intensive processing, and present easy-to-understand visualizations of the
relationships that have been discovered.
An example of such a data-mining application might be a system for a retail business
that sells food and books. Retail businesses maintain separate databases with
detailed information about food products and books. They use a loyalty card system
to keep track of customers’ purchases, so there is a large database linking bar codes
of products with customer information. The marketing department wants to find
relationships between a customer’s food and book purchases. For instance, a relatively
high proportion of people who buy pizzas might also buy crime novels. With
this knowledge, the business can specifically target customers who make specific
food purchases with information about new novels when they are published.