COMS W4156: Advanced Software Engineering

1. COMS W4156: Advanced Software Engineering Prof. Gail Kaiser Kaiser+4156@cs.columbia.edu http://york.cs.columbia.edu/classes/cs4156/ Kaiser: COMS W4156 Fall 2006

2. What is Software Engineering? • Treating computers (including hardware, data structures, algorithms, computations, programming languages, compilers and interpreters, operating systems, databases, networks, graphics, user interface paradigms and devices, etc.) as problem-solving tools • To design and implement solutions to problems • To solve any problem, computers must run some appropriate software that exploits and integrates the resources above • Stakeholders working together as a team – including customers, users, administrators, technical writers and product managers as well as designers, programmers and testers Kaiser: COMS W4156 Fall 2006

3. Why Study Software Engineering? • Writing a program is easy • Developing a software product is hard • Software Engineering aims at supporting the development of high-quality software products • High-quality software products are robust, efficient and effective • High-quality software products are easier to understand, modify, and compose with other high-quality software products • To attain high-quality software, software engineers are skilled professionals who follow defined processes and “best practices” Kaiser: COMS W4156 Fall 2006

4. What do Software Engineers Do? • Newly hired software engineers typically assigned to maintain (or test) someone else’s code • Maintenance: Everything after initial deployment • When was the last time you used a commercial or open source program labeled “Version 1.0”? • 50-90+% of total lifecycle costs • Categories of maintenance • Corrective - reactive modification to correct discovered problems • Adaptive - modification to keep it usable in a changed or changing environment • Perfective - improve performance or maintainability • Preventive - modification to detect and correct latent faults • However, 4156 will focus primarily on development, for practical reasons Kaiser: COMS W4156 Fall 2006

5. Who am I? • Gail Kaiser • kaiser+4156@cs.columbia.edu • Professor at Columbia for >20 years (!) • BS from MIT, MS and PhD from CMU • Worked summers and/or consulted for startups, defense contractors, industry research labs, Software Engineering Institute, Educational Testing Service, Center for Computational Learning Systems • Research in self-managing systems ("autonomic computing"), software testing, publish/subscribe event systems, computer and network security, applied AI, Web technologies, collaborative work, information management, distributed systems, and software development environments and tools Kaiser: COMS W4156 Fall 2006

6. Who is the TA? • Mr. Anurag Chakravarti • ac2491@columbia.edu • 2nd year MS • Two years professional experience in SIP-based networking systems Kaiser: COMS W4156 Fall 2006

7. Who are you? • Seniors and graduate students in Computer Science, Computer Engineering, Biomedical Informatics, maybe others • Sincerely interested in learning to apply Software Engineering methodologies and technologies – not just programming skills - to building and maintaining useful and usable software products Kaiser: COMS W4156 Fall 2006

8. Textbooks • Clemens Szyperski, Component Software: Beyond Object Oriented Programming, 2nd edition, Addison-Wesley, ISBN 0201745720 • Ron Patton, Software Testing, 2nd edition, Sams Publishing, ISBN 0672327988 • Ordered for this class through the Columbia University Bookstore Kaiser: COMS W4156 Fall 2006

9. Assignments • Most course work revolves around a team project • Students work primarily in pairs (2 people) • Grouped into 2-pair teams (4 people) • Each team will build a very small software system • 2 rapid iterations of project - each 3-4 weeks long • Major system functionality should be (more or less) operational by the end of the 1st iteration • 2nd iteration will focus on quality assurance issues Kaiser: COMS W4156 Fall 2006

10. Pairs and Teams • Pairs ideally self-chosen – find a partner • Meet someone in class or advertise on the 4156 discussion forum on CourseWorks (http://courseworks.columbia.edu) • 2 pairs may request each other for a team • Unattached individuals and pairs will be assigned by the teaching staff • Each team will submit a proposal for the very small system they want to build Kaiser: COMS W4156 Fall 2006

11. Computer Accounts You may use any account you like, provided you can • Access the class website and CourseWorks • Submit written assignments in plain text, MS Word or Adobe PDF • AND last but not least… Kaiser: COMS W4156 Fall 2006

12. Do the Team Project AS A TEAM • Develop and test your project code together with your programming pair partner • Integrate together with your team’s other pair • Demonstrate your project to the teaching staff • PLEASE use same programming language, operating system platform, programming environments and tools !!! Kaiser: COMS W4156 Fall 2006

13. Exams • Midterm and Final "Individual Assessments" • Take-home assignments that must be completed by each student working individually • Demonstrate your understanding of software engineering principles and how they apply to your team project • Evaluate your own, your partner’s and your team’s work on the project thus far • No other exams Kaiser: COMS W4156 Fall 2006

14. Final Grade Breakdown • 50% Team Project • 2 iterations at 25% each • 35% Individual Assessments • 15% midterm • 20% final • 15% Individual Development Assignments • A fewsmall homeworks to develop and demonstrate proficiency on component-based technologies • To acquire skills to be used in the team project Kaiser: COMS W4156 Fall 2006

15. Frequently Asked Questions • Do I have to join a pair/team? • YES! • Can I do the project alone? • NO! Kaiser: COMS W4156 Fall 2006

16. Course Outline • Component-based software development • Component models and frameworks • Quality assurance • Code review, unit and integration testing • Other software engineering topics • Pair programming, requirements, software process, refactoring, UML, ??? Kaiser: COMS W4156 Fall 2006

17. Pair Programming Overview • Two programmers work side-by-side at one computer • Continuously collaborate on same design, algorithm, code, test, etc. • Continuous informal review Kaiser: COMS W4156 Fall 2006

18. What about productivity? • Demonstrated to improve productivity and quality of software products • Two programmers work together nearly twice as fast and think of more solutions to a problem as two working alone • While attaining higher defect prevention and defect removal • One well-known empirical study (by Laurie Williams) • 15% lower overall productivity • But 50% fewer bugs (85% tests passed vs. 70%) • http://www.cs.utah.edu/~lwilliam/Papers/ieeeSoftware.PDF Kaiser: COMS W4156 Fall 2006

19. All I Really Need to Know I Learned in Kindergarten : Uncommon Thoughts on Common Things Robert Fulghum, 1988 Kaiser: COMS W4156 Fall 2006

20. All I Really Need to Know about Pair Programming I Learned in Kindergarten. Laurie Williams and Robert R. Kessler. Communications of the ACM, 43(5):108-114, May 2000. http://collaboration.csc.ncsu.edu/laurie/Papers/Kindergarten.PDF Kaiser: COMS W4156 Fall 2006

21. Share everything • Two programmers are assigned to jointly produce one artifact • One person typing or writing, the other continuously reviewing • Both equal participants • Both partners own everything Kaiser: COMS W4156 Fall 2006

22. Play fair • One person “drives” while the other continuously reviews • Important to take turns “driving”, even if one programmer much more experienced than other • Observer is active and engaged, not passive • Continuous analysis, design and code reviews Kaiser: COMS W4156 Fall 2006

23. Don’t hit your partner • But make sure your partner stays focused and on-task • Less time wasted (reading email, IMing, surfing web, etc.) than when working alone, since partner awaiting continuous contribution and input • Each partner expects the other to follow prescribed development practices Kaiser: COMS W4156 Fall 2006

24. Put things back where they belong • Put negative thoughts in the trash can • Very difficult to work with someone with great insecurity or anxiety about their programming skills • Should view pair programming as an opportunity to improve skills by watching and obtaining feedback • Also difficult to work with big egos • No one is infallible and above the input of another Kaiser: COMS W4156 Fall 2006

25. Clean up your mess • Many obvious but unnoticed defects become noticed by another person watching over your shoulder • Defects removed without the animosity that might develop during a formal inspection meeting Kaiser: COMS W4156 Fall 2006

26. Don’t take things too seriously • Ego-less programming • Don’t be defensive with receiving criticism • But don’t always just agree with your partner • Initial adjustment period to pair programming in general and partner in particular Kaiser: COMS W4156 Fall 2006

27. Say you’re sorry when you hurt somebody while moving furniture • Appropriate workspace layout critical to success • Slide the keyboard, don’t move the chairs • Effective communication, within pairs and among pairs, is paramount • Programmers need to see each other, ask each other questions, and make decisions on things such as integration issues Kaiser: COMS W4156 Fall 2006

28. Wash your hands of skepticism before you start • Partner buy-in critical to success • A jelled team is a group of people so strongly knit that the whole is greater than the sum of the parts Kaiser: COMS W4156 Fall 2006

29. Flush • When pair programmers work on something independently, need to throw away and then rewrite jointly • Or at least review jointly – but more likely then to still have defects Kaiser: COMS W4156 Fall 2006

30. Warm cookies and cold milk are good for you • Pair programming can be very intense and mentally exhausting • Periodically take a break Kaiser: COMS W4156 Fall 2006

31. Live a balanced life – learn some and think some and draw and paint and sign and dance and play and work every day some • Communicate with others on a regular basis • Most programmers would probably say they preferred to work alone in a place where they wouldn’t be disturbed by other people • But informal discussions allow for effective idea exchange and efficient transfer of information Kaiser: COMS W4156 Fall 2006

32. Take a break from working together every afternoon • Might do experimental prototyping, tough deep concentration problems, and logical thinking alone • Simple, well-defined, rote coding more efficiently done alone and then reviewed with a partner Kaiser: COMS W4156 Fall 2006

33. When you go out into the world, watch out for traffic, hold hands and stick together • No competition between the paired programmers • Both work for a singular purpose • Do not place blame for defects or problems on either partner • Pair should trust each other’s judgment and loyalty to the team Kaiser: COMS W4156 Fall 2006

34. Be aware of the power of two brains • When two people working together, each has own set of knowledge and skills • Large common subset allows to interact effectively • Pool resources to accomplish tasks Kaiser: COMS W4156 Fall 2006

35. Kaiser: COMS W4156 Fall 2006

36. What is NOT pair programming? • Splitting up the work • Taking turns doing the work • One person doing all the work • Being located in different places • Sitting at different computers • (Exception – it’s ok to use remote shared desktop technology, such as VNC, if absolutely necessary) Kaiser: COMS W4156 Fall 2006

37. In-Class Workshop • Form a pair right now (e.g., the person sitting next to you - this does not have to be the same person you will pair with for the team project!) • Spend no more than 10 minutes developing a proposed solution to the assigned problem (to be announced in class) • Spend no more than 5 minutes writing up your approach in the provided blue book (partners take turns writing) • Submit before leaving class Kaiser: COMS W4156 Fall 2006

38. Pair Formation assignment due Thursday September 14th • Find a partner • Make sure your schedules are compatible! • Make sure you both use the same language and platform! • Both submit the assignment (see website) • May optionally indicate the other pair with whom you’d like to work in a team (otherwise will be assigned) • Teams will be announced September 26th Kaiser: COMS W4156 Fall 2006

39. Upcoming • Individual development assignment #1 due September 19th • Individual development assignment #2 due September 26th • Teams announced September 26th • Team project concept due October 3rd • Individual development assignment #3 due October 10th • Revised project concept due October 17th Kaiser: COMS W4156 Fall 2006

40. COMS W4156: Advanced Software Engineering Prof. Gail Kaiser Kaiser+4156@cs.columbia.edu http://york.cs.columbia.edu/classes/cs4156/ Kaiser: COMS W4156 Fall 2006