CS 501: Software Engineering
Lecture 1
Introduction to Software Engineering
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CS 501 Spring 2002
About the Course
Web site: www.cs.cornell.edu/Courses/cs501/2002sp/
Email: cs501@cs.cornell.edu
Instructor: William Arms
Teaching assistants: Matthew Harris, Megha Batra,
Gilbert Rivera
Assistant: Rosemary Adessa
Computer lab: Computer Science Undergraduate Lab,
Upson Hall, Room 315/317.
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CS 501 Spring 2002
Academic Integrity
 Software Engineering is a collaborative activity. You are
encouraged to work together, but ...
 Some tasks may require individual work.
 Always give credit to your sources and collaborators.
Good professional practice: To make use of the expertise of
others and to build on previous work, with proper
attribution.
Unethical and academic plagiarism: To use the efforts of
others without attribution.
See: Code of Academic Integrity on the course web site,
which points to the Cornell code.
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CS 501 Spring 2002
About the Course
Course text:
Pfleeger, Shari Lawrence, Software Engineering Theory
and Practice, second edition. Prentice- Hall 2001
Each week, read one or more chapters. Discussions will
be held in classes on Tuesdays.
Quizzes
Four quizzes held in class on Tuesdays. No examinations.
(See syllabus on the web site for details.)
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CS 501 Spring 2002
Projects
The Course is Built Around the Projects
 Real project for real client who intends to use the software in
production.
 Select your own project, any branch of software engineering
 Project teams, about 5 to 7 people.
 Feasibility study and plan: due February 15
 Group presentations and reports:
requirements, design, final
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CS 501 Spring 2002
Project Selection
Read the web site
 Some projects on the web site
 Some projects on the web site
 Suggest projects will be discussed in class on Thursday
Contact potential clients
 Gain idea of their expectations
 Estimate scope and complexity of the project
 Discuss business decisions
Assemble project team
 Advertise at the beginning of class
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CS 501 Spring 2002
Thoughts about Project Selection
Projects
•
Target must be a production system (not research)
•
Client should be one or two designated people -- client
should be prepared to meet with you regularly and attend the
presentations
Team
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•
Teams need many strengths -- organizational, technical,
writing, etc.
•
Consider appointing a leader to coordinate the effort
CS 501 Spring 2002
Grading (Subject to Change)
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Project (group)
40%
Project (individual)
20%
Discussion classes
20%
Quizzes
20%
CS 501 Spring 2002
COM S 730 - Seminar on Scholarly
Information Architecture
This seminar course will examine on-line information systems
designed for scholarly usage, covering ongoing trends and
highlighting current problems and new research directions. Topics
will include techniques for rendering, indexing, and linking scholarly
information, and also formats and protocols for querying, accessing,
mining, and transmitting the information. Examples include
automated classification systems, real-time closeness measures,
authoring tools, and next-generation document formats to facilitate
efficient datamining and long-term archival stability. Some of the
non-technical obstacles to realization of ideal systems -- sociological,
legal, financial, and political -- will also be examined.
Prof. Paul Ginsparg, Physics and Computer Science
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CS 501 Spring 2002
Overall Aim of the Course
We assume that you are technically proficient. You know a
good deal about computing, can program reasonably, can
learn more on the job.
When you leave Cornell, you are going to work on
production projects where success or failure costs
$millions.
Soon you will be in charge! It may be your money!
We want you to make your mistakes now and learn from
your mistakes.
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CS 501 Spring 2002
Previous Experience (Yours)
Your background






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Biggest program that you have written?
Biggest program that you have worked on?
Biggest project team that you have been part of?
Longest project that you have worked on?
Most people who have used your work?
Longest that your project has been in production?
CS 501 Spring 2002
Observations about Big Projects
•
A course project is about 0.3 person/years. A big project is
1,000+ person years.
•
Every important program is written by many people, who are
constantly changing.
•
Before a big project is completed the requirements have
changed many times.
•
No large system is ever complete.
Nobody comprehends more than a fraction of the project.
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CS 501 Spring 2002
Future Experience
What will you be doing one year from now?
Ten years from now?
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CS 501 Spring 2002
Previous Experience (Mine)
Much of my career, I was in charge of computing at Dartmouth
and Carnegie Mellon, with some time in industry.
Programs where I wrote most of the code
 Financial system (convertible bonds with sinking
funds)
 Linear and integer programming package
 Graphical language extension
little recent programming experience
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CS 501 Spring 2002
Previous Experience (Mine)
Projects where I was in charge
 Operating system rewrite, compilers, etc.
 Two campus networks, routers, SNMP, etc.
 Distributed computing environment, file systems, etc.
 Administrative data processing, general ledger, etc.
 Digital libraries (including current large project for the
National Science Foundation)
Theme has been first production system where the methods
have previously been used only in research.
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CS 501 Spring 2002
Course Themes
1. Leadership of large software projects
 Software as a product
Clients and their needs
Quality
 Requirements and specification
Usability
Evolution
 Project management
Personnel management
Economic, legal, and social factors
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CS 501 Spring 2002
Course Themes
2. Large and very large systems
 Software design
Software architecture
Object-oriented design
 Dependable systems
Reliability
Verification
 Legacy systems
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CS 501 Spring 2002
Course Themes
3. Risk
 Problems
Over budget
Late
Does not work
 Never used
Does the wrong thing
Needs change
Users dislike to use it
etc.
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CS 501 Spring 2002
Software as a Product
Software is expensive!
The major cost is your salary!
Every software project has a trade-off between:
Functionality
Resources (cost)
Timeliness
Example:
Andrew console monitor
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CS 501 Spring 2002
Client (a.k.a. Customer)
 The client provides resources and expects some product
in return.
 Client satisfaction is the primary measurement of
success.
Question: Who is the client for Microsoft Excel?
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CS 501 Spring 2002
Variety of Software Products
Examples?
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CS 501 Spring 2002
Variety of Software Products
Examples
Real time:
air traffic control
Embedded systems: digital camera, GPS
Data processing:
telephone billing, pensions
Information systems: web sites, digital libraries
Sensors:
weather data
System software:
operating systems, compilers
Communications:
routers, mobile telephones
Offices:
word processing, video conferences
Scientific:
simulations, weather forecasting
Graphical:
film making, design
etc., etc., etc., ....
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CS 501 Spring 2002
Characteristics of All Software Products
General characteristics
Usability
Maintainability
Dependability
Efficiency
Good software products require good programming,
but ...
Programming quality is the means to the end, not the
end itself.
Example: DEC's optical scanner
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CS 501 Spring 2002
Categories of Product
Categories of client and software product:
 Generic (e.g., Microsoft Excel)
 Bespoke (customized) (e.g., IRS internal
system)
Many systems are customized versions of generic
packages (e.g., Cornell's payroll system)
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CS 501 Spring 2002
Variety of Software Products
Software products are very varied
--> Client requirements are very different
--> There is no standard process for software engineering
--> There is no best language, operating system, platform,
database system, development environment, etc.
A skilled software developer knows about a wide variety of
approaches, methods, tools. The craft of software engineering
is to select appropriate methods for each project and apply them
effectively.
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CS 501 Spring 2002
Professional Responsibility
Organizations put trust in software developers:
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•
Competence: Software that does not work effectively can
destroy an organization.
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Confidentiality: Software developers and systems
administrators may have access to highly confidential
information (e.g., trade secrets, personal data).
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Legal environment: Software exists in a complex legal
environment (e.g., intellectual property, obscenity).
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Acceptable use and misuse: Computer abuse can paralyze an
organization (e.g., the Internet worm).
CS 501 Spring 2002
Next Steps
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•
Selection of projects -- read the web site.
•
Form project teams.
•
Read the first Chapter of Pfleeger.
CS 501 Spring 2002