1. What is Software Engineering?
Engineering is about getting technology to do what it does well
so humans can do
what they do well
Jeff Offutt
Professor of Software Engineering Volgenau School of Engineering
George Mason University

2. Who Am I ? Jeff Offutt Parent : Steffi (26), Joyce (22), Andrew (14)
Education : BS (Math, Data Processing),
PhD (Computer Science, 1988)
Professor : GMU, Software
Engineering, Volgenau School
Scientist : >175 refereed papers
Leader : Journal of Software Testing, Verification, and Reliability; IEEE Conference on Software Testing; MS-SWE program
CS 101, February 2017
© Jeff Offutt

3. Today’s Talk
What is Software Engineering and how is it related to Computer Science?
What Software Engineering educational opportunities does GMU offer?
Software Engineering quality attributes
Testing: Can I break it? Yes I can!
Usability: Can I use it?
CS 101, February 2017
© Jeff Offutt

4. Comparing Computing Fields
Software Engineering A b s t r a c i o n
Calc-1, discrete math, graphs, logic
design, test, maintenance, programming, web apps, …
How to design, test, maintain
& build large, high quality programs
Computer Science
Calc-2, discrete math, CS theory
Programming, …
How to make computers work
Algorithms, programming, …
Computer Engineering
Calc-3, discrete math (logic, algebra)
3-4 programming / CS
Computer components
Chips, memory, cpu, …
Electrical Engineering
Anything that uses power
Transistors, batteries, transformers, …
Calc-4
1-2 programming
Calc-4, real analysis, …
1 programming
Physics
How the universe works …
CS 101, February 2017
© Jeff Offutt

5. Engineers and Scientists
Science is about adding to the knowledge base
Engineering uses the knowledge to solve problems
Science is discovery
Engineering is invention
Engineers use science to build things to improve our lives
CS 101, February 2017
© Jeff Offutt

6. Goals of Science and Engineering
Behaviors
observe
achieve
find and
describe
Science
Engineering
design and
develop
Structures
CS 101, February 2017
© Jeff Offutt

7. Computer Science and Software Engineering
Computer Science is about
fundamentally understanding
what we can do with computing devices
Software engineering is about
building high quality computing solutions
to real-life problems
CS 101, February 2017
© Jeff Offutt

8. Outline of Today’s Talk
What is Software Engineering and how is it related to Computer Science?
What Software Engineering educational opportunities does GMU offer?
Software Engineering quality attributes
Testing: Can I break it? Yes I can!
Usability: Can I use it?
CS 101, February 2017
© Jeff Offutt

9. Undergraduate Opportunities
Applied Computer Science
Concentration in Software Engineering
Minor in Software Engineering
8 undergrad SWE courses
Accelerated program into the MS-SWE program
Offered by the
Department of Computer Science
CS 101, February 2017
© Jeff Offutt

10. Distinguishing SWE and CS
Reliability
Maintainability
Building High Quality Software
specifying, modeling, designing, implementing, evaluating, deploying, maintaining, …
Scalability
Usability
Security
Availability
etc. ...
Fact: Engineering software is distinct from the science of computing
Goal: Give UG students a coherent treatment of engineering software
CS 101, February 2017
© Jeff Offutt

11. ACS Software Engineering
Essentials of Computer Science Degree
ACS Foundation:
CS 101, 105, 112, 211; Math 113, 114, 125, 203
ACS Core:
CS 262, 310, 330, 367, 321, 465, 483, 4xx; ECE 301
Software Engineering Essentials
SWE Foundation and Core:
SWE 205: Software Usability
SWE 301/401: Intern Prep & Reflect
SWE 332: OO Design & Impl
SWE 437: Software Test & Maint
STAT 344; CS 306
SWE Related: 15 Hours From
SWE 432, 443
CS 363, 450, 455, 468, 471, 475
Communication/Organizational Skills
Cross Disciplinary:
ENGH 410: Prof / Tech Writing
One of PSYC 333, COMM 320, COMM 335
CS 101, February 2017
© Jeff Offutt

12. SWE Advising Notes
If you are ACS / SWE, your advisor should be one of :
Paul Ammann
Jon Bell
Kinga Dobolyi
When meeting your advisor, you should first visit the degree requirements page:
Then fill out the ACS / SWE study plan spreadsheet:
Hassan Gomaa
Thomas Latoza
Jeff Offutt
CS 101, February 2017
© Jeff Offutt

13. Software Engineering Minor
CS 112 (4 hrs)
CS 211 (3 hrs)
9 hours from these 6 courses
CS/SWE 332
SWE 432
CS/SWE 321
SWE 437
SWE 443
SWE 205
SWE 205 – Usability Analysis and Design
CS / SWE 332 – OO software
CS / SWE 321 – Intro to software engineering
SWE 432 – Software usability and web software
SWE 437 – Software testing and maintenance
SWE 443 – Software architectures
CS 101, February 2017
© Jeff Offutt

14. Outline of Today’s Talk
What is Software Engineering and how is it related to Computer Science?
What Software Engineering educational opportunities does GMU offer?
Software Engineering quality attributes
Testing : Can I break it? Yes I can!
Usability : Can I use it?
CS 101, February 2017
© Jeff Offutt

15. Software is the Nervous System of Our Civilization
Quote partially due to Dr. Mark Harman
CS 101, February 2017
© Jeff Offutt

16. Outline of Today’s Talk
What is Software Engineering and how is it related to Computer Science?
What Software Engineering educational opportunities does GMU offer?
Software Engineering quality attributes
Testing: Can I break it? Yes I can!
Usability: Can I use it?
CS 101, February 2017
© Jeff Offutt

17. Spectacular Software Failures
NASA’s Mars lander : September 1999, crashed due to a units integration fault
Ariane 5: exception-handling bug : forced self destruct on maiden flight (64-bit to 16-bit conversion: about 370 million $ lost)
Mars Polar Lander crash site?
Toyota brakes : Dozens dead, thousands of crashes
Major failures : Ariane 5 explosion, Financial engines, Intel’s Pentium FDIV bug
Poor testing of safety-critical software can kill :
THERAC-25 radiation machine: 3 dead
THERAC-25 design
Software testers try to find faults before the faults find users
CS 101, February 2017
© Jeff Offutt

18. Airbus 319 Safety Critical Software Control
Loss of autopilot
Loss of most flight deck lighting and intercom
Loss of both the commander’s and the co‑pilot’s primary flight and navigation displays !
CS 101, February 2017
© Jeff Offutt

19. Northeast Blackout of 2003
508 generating units and 256 power plants shut down
Affected 10 million people in Ontario, Canada
Affected 40 million people in 8 US states
Financial losses of
$6 Billion USD
The alarm system in the energy management system failed due to a software error and operators were not informed of the power overload in the system
CS 101, February 2017
© Jeff Offutt

20. What is Testing & Why is It Hard?
Software Testing
tries to find software faults before users do
A program can have quadrillions of inputs.
And will work correctly on most!
If a million inputs trigger the fault.
Only chance of finding it ...
Software Testers
try to find test inputs that will trigger the faults before they get to users
CS 101, February 2017
© Jeff Offutt

21. Testing Student Programs
Programming
Assignment
Submit
Debugging
Does it work ?
All the time ?
Maybe not …
Customers care !
Thus …
your employer will care !
Who cares ?
CS 101, February 2017
© Jeff Offutt

22. Software Testing in Real Life
Needs or idea
Requirements
Deployment
Future
Evolution
Unrecoverable
Common !!
System Test
Architecture
Disaster!
Very expensive
Full System
Design
Expensive
Integration
Test
Programming
Unit Test
Integrate
CS 101, February 2017
© Jeff Offutt

23. Debugging Sucks Testing Rocks Google’s Motto CS 101, February 2017
© Jeff Offutt

24. Finding faults early saves LOTS of money
Cost Of Late Testing 60 50 40 30 20 10
Assume $1000 unit cost, per fault, 100 faults
$250K
$35K
$360K
$150K
Fault origin (%)
Fault detection (%)
Unit cost (X)
$18K
$20K
$100K
$13K
$100K
$6K
$50K
Total Savings
$190K
Requirements
28-Oct-2010, at GTAC, added the animation to demonstrate increasing the number of faults found early, thereby decreasing the number of faults found late, and finally saving money. Lots of it! This animation is fairly complicated … must practice first!!
Design
Prog / Unit Test
Integration Test
System Test
Production
Software Engineering Institute; Carnegie Mellon University; Handbook CMU/SEI-96-HB-002
Finding faults early saves LOTS of money
CS 101, February 2017
© Jeff Offutt

25. What Do Testing Researchers Do?
Software Testing Researchers
invent clever ways to design inputs that will find software faults
Build software tools to create tests
Run experiments to find out how well the testing ideas work
Tell industry how to use the ideas
Teach students – the next generation of software testers
CS 101, February 2017
© Jeff Offutt

26. Outline of Today’s Talk
What is Software Engineering and how is it related to Computer Science?
What Software Engineering educational opportunities does GMU offer?
Software Engineering quality attributes
Testing: Can I break it? Yes I can!
Usability: Can I use it?
CS 101, February 2017
© Jeff Offutt

27. Usable software should be :
What is Usability?
The ability for a typical user to effectively accomplish a task without needing external help
Usable software should be :
Learnable within with reasonable effort
Tolerant of reasonable user mistakes
Efficient to use without undue effort
CS 101, February 2017
© Jeff Offutt

28. User Manuals are Just Wrong
If a simple interface needs a user manual, something is probably wrong
CS 101, February 2017
© Jeff Offutt

29. Example: Error Messages
People are poor at being perfect …
but pretty good at getting “close”
Make all actions undoable
Make it easy to discover mistakes (visibility)
Make it easy to correct mistakes
Do not think in terms of “users making errors,” think in terms of users getting close
CS 101, February 2017
© Jeff Offutt

30. A Poor Error Message
CS 101, February 2017
© Jeff Offutt

31. A Poor Error Message I did! Maybe I need 50 cents … 50
CS 101, February 2017
© Jeff Offutt

32. A Poor Error Message Must enter 2 zeros (other values not allowed) 0050 00
CS 101, February 2017
© Jeff Offutt

33. More Bad Examples
! HT ACCESS: Error accessing “ “HTTP: File/directory does not exist”
The requested web page /offutt.html was not found on ...
: Microsoft OLE DB Provider for ODBC Drivers error ' '
[Microsoft][ODBC SQL Server Driver][SQL Server]Your transaction (process ID #85) was deadlocked with another process and has been chosen as the deadlock victim. Rerun your transaction.
/script/webkatalogen/pb.asp, line 221
Internal failure, please try again.
CS 101, February 2017
© Jeff Offutt

34. More Bad Examples Bus error, core dumped (Unix)
Access through a nil pointer in function GetNext()
Terminating thread, due to a stack overflow problem. A VxD, possibly recently installed, has consumed too muhc stack space. Increase the setting of MinSPs in SYSTEM.INI or remove recently installed VxDs. There are currently 5 SPs allocated. (Windows 2000)
???
CS 101, February 2017
© Jeff Offutt

35. https://cs.gmu.edu/~offutt/
Summary
Software Engineering & Computer Science
Software Engineering Mason
Software Engineering quality attributes
What is software testing?
What is software usability?
Jeff Offutt
4430 Engineering Building
CS 101, February 2017
© Jeff Offutt