Object Structures

1
Object Structures

• Class Introduction

2
Topics in this Lecture

• About the instructor
• About each of you
• Why computer science is a great place to be
• Why this class is critical to your success
• The whole subject in 30 minutes or less
• Syllabus review
• QA

3
About James Madison

• Computer operations in Desert Storm, 1990-1991
• Awarded the highest single medal in my unit
• Central Connecticut State University, New
  Britain, CT
• B.S. in Computer Science, changed major due to
  elective
• Hardware track wanted to understand down to
  silicon level
• 1995 Computer science department honor student
• Graduated 1996, 3.96 GPA, 4th in a class of
  1,400
• Rensselaer Polytechnic University, Hartford, CT
• M.S. in Computer Science
• Graduated 2006, 4.0 GPA
• Professional experience
• 10 years in the insurance industry
• Worked at nearly every layer of the technology
  stack

4
About Each of You

• Why are you taking this class?
• From a broad perspective, not just as a
  requirement
• What do you hope to know by the end that you
  dont now?
• Academic background
• In general major, special focuses, etc.
• Math classes discrete math in particular
• Imperative languages you know and how much
• Professional experience
• Background and current status

5
Why Computer Science

• This is a transitional class, so many of you
  probably come from non-CS backgrounds
• Welcome to a great field of endeavor
• I would like to reinforce your choice in the
  following few slides because
• There is a great deal of misperception in the
  public view about our field and how great it is
  to be here
• Our field requires hard work and can be stressful
  at times. I want to offer some encouraging
  thoughts and useful perspective for such
  situations.

6
Why Computer Science

• Computer science is everywhere
• It provide great job security and pay
• But it requires solid skills and their useful
  application
• The outsourcing hype will pass
• The outsourcing reality will require some
  adaptation
• Freshman enrollments are down 50 in 4 years
• Reduction in supply drives up price (i.e. your
  salary!)
• Baby boomers will be retiring
• Hits all fields, but knowledge fields like CS in
  particular
• Further reduction in supply further drives up
  price
• The many quotes that follow are from recent
  issues of industry journals and support the above
  assertions

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Why CS - Job Security

• a survey of 27,108 IT workersshow job security
  is on the rise.
• -- ComputerWorld, front page, 6/19/06
• the U.S. tech unemployment rate hovering around
  3, near its record low, and tech employment
  above 3.4 million, near its all-time high
• -- CIO Magazine, via federal data, 6/12/06
• According to the Bureau of Labor Statistics, one
  out of every four new jobs between now and 2012
  will be IT-related.
• -- Mark Hanny, VP of IBMs Academic Initiative
  outreach program, ComputerWorld, 7/17/06

8
Why CS Outsourcing Hype

• The numbers dont add up. China and India
  arent turning out nearly as many engineers as
  commonly believed, Duke University researchers
  report. And theyre probably not as well-trained
  as their U.S. counter parts.
• -- E-week Magazine, 6/5/06
• Indian software companies are facing a labor
  crunch similar to what U.S. companies experienced
  five years ago
• -- InformationWeek Daily Newsletter, 6/5/06

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Why CS Dropping Skill Supply

• The number of kids who are choosing to major in
  computer science has plummeted by nearly half
  since its peak of 3.7 percent of freshmen in
  2000, according to the Higher Education Research
  Institute at the Graduate School of Education and
  Information Studies at UCLA.
• -- CIO Magazine, 5/1/06
• Were seeing a lack of talented IT professionals
  looking for new positions.
• -- Greg Fittinghoff, VP at Time Inc.,
  ComputerWorld, 7/17/06

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Why CS Real Trends to Consider

• But you have to be skilled and have the right
  kind
• Recent reports that the offshoring impact on the
  U.S. job is overblownat least for IT positions
  requiring advanced degrees and business
  knowledge
• -- InformationWeek Daily Newsletter, 6/5/06
• You have the first half underway by taking this
  class
• The business knowledge is keyneed to do that too
• Personally, Im studying for an insurance
  underwriting exam
• CIOs increasingly demand that their programmers
  understand the business
• -- Christopher Koch, executive editor of CIO
  Magazine, 5/1/06

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Why CS Real Trends to Consider

• The grumpy-nerd-in-the-corner programmer is
  obsolete
• The friendly-nerd-in-the-business-meeting
  programmer is in
• Tacit skills are the current and future trend
• Perform analysis, handle ambiguity, be
  interactive, manage knowledge, communicate
  business value
• Tacit jobs have been growing three times faster
  than employment in the entire national
  economyand they make up 70 of all U.S. jobs
  created since 1998 and 41 percent of the total
  labor market in the U.S.
• -- CIO Magazine, via McKinsey Consulting, 5/1/06

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Why CS Real Trends to Consider

• The number of programmers employed in the U.S.
  has dropped by 25 since its peak in 2000, even
  though the total number of IT workers has
  increased slightly since then
• -- CIO Magazine, via Bureau of Labor Statistics,
  5/1/06
• To restate
• IT work is up from the peak of the dot-com hype
• But the nature has changed away from just
  programming
• So why learn programming? From same article as
  above
• but sometimes you need to be able to go into
  the detail. If you cant go into the detail, you
  wont be able to solve problems.
• Read that last sentence again. It is critical
  truth.

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Why CS Real Trends to Consider

• As with so many things, its not either/or, you
  need both
• Programming knowledge gets to the heart of many
  issues and is critical to solving the most
  advanced problems
• My day job is mostly documentation and
  communication, but my programming knowledge still
  serves me well
• Code was crashing, I figured out why just from
  discussion and was able to point the developers
  in the right direction
• Threading model was heavily in dispute, so I
  wrote it in 16 hours over a weekend and handed it
  off that Monday
• Had to present SOA to 30 major business leaders
  I wrote a working end-to-end system demonstration
  that was vastly more effective at communicating
  business value than would have been a
  presentation of just PowerPoint fluff
• That is, did both the tacit and the concrete with
  equal focus

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Why This Class

• This class has two major values
• Academic positions you for
• Computability and Complexity, a mandatory class
• Operating Systems, a mandatory class
• Object Oriented Programming, frequently offered
• Compiler Design, occasionally offered
• Algorithm Analysis, occasionally offered
• Professional permeates the real-world
• Many things are object-centric, vastly more than
  just code
• Metadata tools, rules engines, enterprise SOA
• Applications performance issues are often
  algorithm problems
• Vendor suites build on data structure principles
• Libraries such as J2EE use nearly all the content
  of this class
• Opens the black box of project and resource
  problems

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Why this Class The CS Sandwich

• Business process management
• Management info systems (MIS)
• Software engineering
• GUI/Web programming
• Database systems
• Networking
• Security and cryptography
• Operating systems
• Compiler design
• Object oriented programming
• Object structures
• Procedural programming
• Computability theory (math)
• Assembler
• Microprocessor design
• Logic gate design
• Silicon design
• Chemistry/physics (science)

Roughly speaking, the stack is most abstract
at the top and gets more specific as you go
down. Dont take it too literally Crypto
can get as detail intensive as assembler,
compiler design actually interacts with several
layers, O.S. could be thought of as a building
block, etc., but for our discussion, its
accurate enough. The key is Object
structures is right at the heart of the
foundation that delivers CS value to the non-CS
world.
Areas of Computer science that other
disciplines can use for their own success
Building blocks that underpin the external areas
Important inner workings that can be
abstracted from most practitioners
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Whole Class at Top Speed

• Main topics for the semester
• Algorithms
• Data structures
• Objects and classes
• For each of these, you will be able to
• Create them and use them to create programs
• Use them in your program when created by others
• Speak intelligently about them, in detail and
  high-level
• Give many real examples, both simple and complex
• Know they are in play based on black box
  behavior
• This is my favoritemakes you a magician
• This is my answer to the previous question of
  what do you hope to learn by the end of the
  semester

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Top Speed - Algorithms

• An algorithm is a set of actions done in a
  specified manner. They are all around us
• Simple Following a recipe when cooking dinner
• Complex A pilot going through the pre-flight
  routine
• Computer code specifies algorithms
• The programmer specifies a set of actions
• The computer does those actions in a precise
  manner
• Algorithms are based in mathematics
• Algorithms can be rigorously proven
• There are known limits to algorithm power
• Its not just well, no one has figured it out
  yet
• This class will take you to the limits of our
  field
• Yes, it is cool, and yes, it will make your head
  spin

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Top Speed Data Structures

• A data structure holds things. Again, life
  examples
• A bookcase holds books
• A phone book holds phone numbers
• Computers have memory structures to emulate
  reflect the real-world construct
• The programmer creates a phone book structure
• Algorithms run against data structures
• The programmer writes an algorithm that searches
  the phone book structure for a particular number
• Data structures are usually simpler to understand
  and work with than algorithms

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Top Speed Objects Classes

• Algorithms data structures tend to travel in
  pairs
• The phone book data structure naturally needs an
  algorithm that searches the phone book
• The phone book search is not the same as
  searching a warehouse for a box
• But the warehouse also needs a search algorithm,
  and it will tend to be useful only for the
  warehouse
• We put the algorithm and data structures together
  into a class of solution
• Phone book algorithm and data structure into the
  phone book class
• Warehouse algorithm and data structure into the
  warehouse class

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Top Speed Objects Classes

• The class of phone book then has specific phone
  book objects
• Hartfords phone book is not the same as New
  Yorks
• The general category of phone books is a class
• The specific instances of the class are objects
  of the class
• The class of warehouses as objects of warehouse
  type
• Wal-Mart and Target both have buildings in the
  class of warehouse, but their warehouse objects
  are different
• Class and object are loosely interchanged in
  conversation
• When the difference matters, I will be precise
• Classes/objects move up and down in level of
  precision
• The class of warehouse is a specific class based
  on the class of building. This leads to
  inheritance and subclassing

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Top Speed Life Examples, Mine

• Dont think computer, just think about life.
  Algorithms, data structures, and classes
  objects around us
• For each of these bullets, mark it A, DS, or
  C/O
• I have a very specific schedule I follow every
  morning
• Children are annoying, but my child is wonderful
• The web is better for phone numbers than a phone
  book
• Computer science is more fun than business
  management
• The object structures class is easier than the
  operating systems class, and the latter must be
  taken first
• You have to start the car before you put it in
  gear
• Politicians are idiots who only care about
  themselves
• PowerPoint doesnt sort data as well as Excel
• I need to recharge my laptop battery

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Top Speed Life Examples, Yours

• Make up some examples yourself, just some ideas
  here
• Personal
• Doing yard work
• Cooking in the kitchen
• Last party of family reunion
• Professional
• Systems you have worked on
• How the departments in your company interact
• Universal
• Planets and stars
• Principles of physics
• Other
• Anything else that maps to the concepts discussed

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Top Speed Mental Exercise

• For the next week, ponder the above examples, and
  ask
• How would I get a computer to do that?
• How were the examples similar and different?
• How would they perform?
• Would some be fast and others take a long
  time?
• It is said that there is no bigger waste of
  energy than to try to do well that which should
  not be done at all
• Would some of these get worse if we programmed
  them?
• Should we instead fundamentally change the
  thought?
• Might some be impossible to solve with a
  computer?
• As noted above, there are such problems
• Did you stumble on one of them?
• How would you know?
• How would you prove it?

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QA

• Anything else?