Case Study:
DefCon is an organization that develops IT solutions for businesses. The product in
consideration is a system for supporting a magazine subscription business, where
information about customers and their subscribed products is collected, stored, and tracked.
Currently, online subscriptions are not possible, so the details of subscriptions are mailed to
the business and entered into the system manually. This business has around 45 employees
with offices in Canberra, Sydney, and Perth. The employees have an option to work from
home, so the system supports remote access.
The basic architecture of the system is presented below:
Clients — Custom
Views
Workstations
gil Controller
Business rule
processing
Multiple layers
Database access
layer
Order and
customer
database (Model)
1. Briefly describe the steps in the Attribute Driven Design (ADD) Process (Word limit 500
words) (4 marks).
2. Considering the following quality attributes as important to this system, follow two
iterations of the ADD process. For each iteration, provide the selected ASR, chosen
tactic, and justification for it (4 marks).
¦ Availability – The system should be available for access during normal operational
hours 99.999% of the time. In case of failure, it should recover within 2 seconds.
¦ Performance – The system handles a large amount of data as there are 90 thousand
customers with more than a million orders. The system should handle this load with a
latency of 1 second.
¦ Security – The system should resist any unauthorized access anytime with 99.999%
accuracy.
¦ Performance – The system should respond to user requests with an average latency
of 1 second.
3. Submit the resulting architecture with clearly defined modifications in the basic
architecture provided (The added components should be clearly labeled) (2 marks). You
can use a pen/pencil to draw the diagram or you can draw it using MS Visio or any other
software or tool.
Note: You need to upload a document that contains the answers to 1, 2, and 3.
Read the description below. Describe the three most important quality attributes for the scenario
described. Identify at least two relevant tactics for each of the quality attributes and justify them
(provide reasoning for their relevance).
A company wants to develop a system for sea buoys to support navigation at sea. Many free-
floating buoys exist that provide navigation and weather data to air and ship traffic at sea. The
buoys use a variety of sensors to collect air and water temperature, wind speed, and location data.
There may be different numbers of temperature and wind sensors in each buoy. In the future, there
is a possibility to add support for other types of sensors. Each buoy also includes a radio transmitter
and a radio receiver so that it can broadcast weather and location information, and an SOS
message, and it can receive requests from nearby passing vessels. Some buoys are equipped with a
red light, which may be activated by a passing vessel during sea-search operations. If a sailor is able
to reach the buoy, he or she may flip a switch on the side of the buoy to initiate an SOS broadcast.
Requirements for software for each buoy are stated below:
• It must maintain current information about temperature, wind, and location; take wind speed
readings every 30 seconds, temperature readings every 20 seconds, and location every 60
seconds.
• It must broadcast current wind, temperature, and location information every 60 seconds.
• It must broadcast wind, temperature, and location information from the past 24 hours in
response to requests from passing vessels; this takes priority over the periodic broadcast
• It must have activation or deactivation of the red light based upon a request from a passing
vessel.
• It must continuously broadcast an SOS signal after a sailor engages the emergency switch; this
signal takes priority over all other broadcasts and continues until reset by a passing vessel.