This presentation is a part of the COP2271C college level course taught at the Florida Polytechnic University located in Lakeland Florida. The purpose of this course is to introduce Freshmen students to both the process of software development and to the Python language. The course is one semester in length and meets for 2 hours twice a week. The Instructor is Dr. Jim Anderson. A video of Dr. Anderson using these slides is available on YouTube at:https://www.youtube.com/watch?feature=player_embedded&v=_gjBvrotoYg

1. An Introduction To Software
Development Using Python
Spring Semester, 2015
Class #2:
Software Design
Methodologies

2. Creating A Software Program
• Customer requirement:
Get out of bed and go to
school.
• Software requirements:
1. Get out of bed
2. Go to the bathroom
3. Go to the kitchen
4. Get cereal bowl, get cereal, get milk, get
O.J., get spoon, get banana
5. Place cereal in bowl, pour milk on it,
peel banana
6. Sit at table
7. Eat cereal in bowl using spoon, eat
banana
8. Go to room
9. Take shower, brush teeth, comb hair
10. Get dressed: shirt, pants, belt, socks,
shoes, watch, jewelry,
11. Grab backpack, laptop, cell phone
12. Shut and lock the door
Image Credit: tec_estromberg

3. 2 Main Concerns Of Any
Software Project
• How much will it cost?
• How long will it take?
Note: there is often a
due date for the software!
Image Credit: Richard Smith

4. Software Engineering
Requirements
Analysis
Specification
Development
Software
Design
Test &
Verification
Maintenance
Image Credit: http://www.tipsforphotographers.com/waterfall-photography-take-stunning-shots-of-waterfalls

5. Design Type: Waterfall
Research Concept Test Design Build
Image Credit: http://www.free-extras.com/search/1/waterfall.htm
http://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet

6. Managing Design Debt
Research Test Design Build Release
Time
Debt
Concept
Cycle Length
Waste

7. Design Type: Agile
Research Concept Test Design Build Design Build Design Build
Iteration 1Iteration 0 Iteration 2 Iteration 3

8. Design Type: Agile
Iteration 1
Time
Debt
Iteration 0 Iteration 2
Cycle Length
Waste

9. Measure
Learn
Build
Design Type: Lean

10. Design Type: Lean
Build
Time
Debt
MeasureLearn
Cycle Length

11. Comparing Design
Approaches
11
Waterfall Agile
Validated Design
Waste
Lean
Over Time

12. Big Bang Software Development
Get requirements from customer
Magical Coding Happens
Exactly what the customer wanted is produced
Image Credit: www.acclaimclipart.com, Matt

13. Why Doesn’t The Big Bang Work?
• You did do a lot of work
• However, you didn’t show
your customer your work
until you were done
• You thought that you were
building what the customer
wanted with no feedback
• Now you will have to do
rework
Image Credit: John Thurm

14. Examples Of Customer Requests
• Designing an intersection:
1. There should be 3-color lights
that indicate if a car should be
able to go or stop.
2. Only one direction should be
able to go at a time
3. Pedestrians should be able to
cross safely
4. If there is a system fault, drivers
should be told
5. Don’t delay other drivers if
nobody wants to turn a given
direction.
Image Credit: John Meckley

15. Customer’s Who Don’t Know
What They Want
• Ask the customer what they mean
• Ask them for more detail
• Ask them for options on how you can
implement their ideas
Image Credit: Daniel

16. What Do Customers Want?
Image Credit: http://ccechildren.wordpress.com/2010/04/15/learning-objectives-and-goals/

17. Iteration Is The Key To
Software Success
Start Finish
Big Bang Software Project
What
The
Customer
Really
Wants
Software
Development
With
Iteration
Customer Changed Their Minds
The secret to developing software correctly is iteration. you need to ask
"how am I doing" at each step in the software development process…

18. Questions About Iteration
• Think of iteration as being a "checkup"
for your software. You'll always know
how you are doing.
• Questions:
– Do you ever know exactly what your customer
wants? No.
– If the project is short, do you still need to iterate?
Yes.
– Why not just nail down requirements before you
start? Customer does not know what they want.
– Who should gather requirements? Tricky question.
– When should iterations start? Every 20 days – one
calendar month.
– What happens if I've screwed up? You fix it starting
now.
Image Credit: BEV Norton

19. How Do We Handle “BIG”
Software Projects?
Instead of trying to build the complete software solution, you need to
break it up into "chunks" that you can then separately show to the
customer.
Image Credit: Don Brubacher

20. How Do We Work With
The Customer?
• You can think of each iteration as being almost a "mini-project" which
includes requirements, design, coding, testing, etc. You will actually be
showing your customer well developed pieces of software that you will
eventually all fit together.
• When you've checked the software at the end of each iteration, you have
a much better chance that this is the software that the customer wants.
Get
Requirements
Design
Solution
Code
Solution
Test
Solution
One mini-project
Talk With
Customer

21. How To Manage Requirements
• Write each requirement on a card
• Give each requirement a name
• Create an estimate for how long it will take to
design / code this requirement
• Determine the customer’s priority for this
requirement (1=High, 5=Low).
Image Credit: London Permaculture

22. Our Intersection Example (Again)
Title: Red/Yellow/Green Light
Estimate: 12 days
Customer Priority: 1
Title: Right Turn Arrow
Estimate: 3 days
Customer Priority: 4
Title: Left Turn Arrow
Estimate: 3 days
Customer Priority: 4
Title: Traffic Based Scheduling
Estimate: 20 days
Customer Priority: 2
Title: Flashing Yellow Fault
Estimate: 2 days
Customer Priority: 3
Title: Multiple Lights Same Direction
Estimate: 4 days
Customer Priority: 2
Title: Right / Left Green Light
Estimate: 6 days
Customer Priority: 1

23. Scheduling The Work
20 Days
Title: Traffic Based Scheduling
Estimate: 20 days
Customer Priority: 2
Title: Red/Yellow/Green Light
Estimate: 12 days
Customer Priority: 1
Title: Right / Left Green Light
Estimate: 6 days
Customer Priority: 1
Title: Flashing Yellow Fault
Estimate: 2 days
Customer Priority: 3
Image Credit: Clipart Panda

24. How Much Iteration Is Too Much?
• The goal of iterations is to catch yourself early when you are
deviating from a goal; however, you don't want to end up
spending all of your time preparing for another discussion
with the customer.
• It is always better to deliver some of the customer's features
working perfectly instead of all of the customer's features not
working properly.
• Customers change their minds. This will end up changing your
project.
Image Credit: Creative Tools

25. What We Covered Today
1. Different ways to create
software code.
2. Why “The Big Bang”
doesn’t work.
3. Why iteration is what is
needed to stay on track.
4. How to manage
requirements.
Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/

26. What We’ll Be Covering Next Time
1. What to do when a
customer adds new
requirements
2. What is a software
development process?
3. When is a software
development project
done?
Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/