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160 S o f t w a r e & S y s t e m s R e q u i r e m e n t s E n g i n e e r i n g : I n P r a c t i c e

Manage System
Automation Rule
Feature: Alarm
Manage Alarm Management
Manage Standard
Facilities Operating Procedures
manager
Public
Handle Alarm safety system
<<include>>
<<include>> Follow SOP
Issue <<include>>
Command
Feature:
Personalize UI
Personalization
Notify Change Feature: Event
of Value Management
Field system Feature: Field Device
Manage Field Management
Devices Feature: Dynamic
Field engineer Reconfiguration
Feature: Access
Manage Users
Control
System
administrator
FIGURE 5.6 Use cases

attributes corresponding to these goals. These scenarios must be
specific enough that a system can be evaluated to determine if it
satisfies a given scenario. Table 5.6 shows a mapping of the business
goals to quality attribute scenarios for the building automation
system.

Constraints on the Architecture
While the features define a product and the quality attributes play a
significant role in shaping its architecture, there are additional factors
that may constrain how the architecture will be designed. For instance,
it may be the case the system under consideration has to be developed
on the Microsoft .NET platform and needs to use the Oracle DBMS.
This a priori choice of technology will limit the ability of an architect
to make design decisions such as how the system is partitioned into
tiers; the communication mechanisms across these tiers; and the
strategies for security, failover, and transaction management.
As discussed earlier, global analysis is a technique for analyzing
a wide variety of factors that may become constraints for creating the
architecture. Table 5.7 enumerates a few such factors for the building
automation system.