Sommerville-Software-Engineering-10ed

566 Chapter 19 ■ Systems engineering
Digital art
Jill is an S2 pupil at a secondary school in Dundee. She has a smartphone of her own, and the family has a
shared Samsung tablet and a Dell laptop computer. At school, Jill signs on to the school computer and is presented
with a personalized Glow+ environment, which includes a range of services, some chosen by her teachers
and some she has chosen herself from the Glow app library.
She is working on a Celtic art project, and she uses Google to research a range of art sites. She sketches out
some designs on paper and then uses the camera on her phone to photograph what she has done; she uploads
this using the school wifi to her personal Glow+ space. Her homework is to complete the design and write a
short commentary on her ideas.
At home, she uses the family tablet to sign on to Glow+, and she then uses an artwork app to process her
photograph and to extend the work, add color, and so on. She finishes this part of the work, and to complete it
she moves to her home laptop to type up her commentary. She uploads the finished work to Glow+ and sends
a message to her art teacher that it is available for review. Her teacher looks at the project in a free period
before Jill’s next art class using a school tablet, and, in class, she discusses the work with Jill.
After the discussion, the teacher and Jill decide that the work should be shared, and so they publish it to the
school web pages that show examples of students’ work. In addition, the work is included in Jill’s e-portfolio—
her record of schoolwork from age 3 to 18.
Figure 19.8 A user story
used in a system vision
document
User stories are effective because, as already noted, readers can relate to them; in
addition, they can show the capabilities of the proposed system in an easily accessible
way. Of course, these are only part of a system vision, and the summary must
also include a high-level description of the basic assumptions made and the ways in
which the system will deliver value to the organization.
19.3 System procurement
System procurement or system acquisition is a process whose outcome is a decision
to buy one or more systems from system suppliers. At this stage, decisions are made
on the scope of a system that is to be purchased, system budgets and timescales, and
high-level system requirements. Using this information, further decisions are then
made on whether to procure a system, the type of system required, and the supplier
or suppliers of the system. The drivers for these decisions are:
1. The replacement of other organizational systems If the organization has a mixture
of systems that cannot work together or that are expensive to maintain, then
procuring a replacement system, with additional capabilities, may lead to
significant business benefits.
2. The need to comply with external regulations Increasingly, businesses are regulated
and have to demonstrate compliance with externally defined regulations
(e.g., Sarbanes–Oxley accounting regulations in the United States). Compliance
may require the replacement of noncompliant systems or the provision of new
systems specifically to monitor compliance.