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1 CS 501 Spring 2002
CS 501: Software Engineering
Lecture 1
Introduction to Software Engineering
2 CS 501 Spring 2002
About the Course
Web site: www.cs.cornell.edu/Courses/cs501/2002sp/
Email: [email protected]
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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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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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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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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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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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
• Teams need many strengths -- organizational, technical, writing, etc.
• Consider appointing a leader to coordinate the effort
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Grading (Subject to Change)
Project (group) 40%
Project (individual) 20%
Discussion classes 20%
Quizzes 20%
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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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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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Previous Experience (Yours)
Your background
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?
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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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Future Experience
What will you be doing one year from now?
Ten years from now?
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Previous Experience (Mine)
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
Much of my career, I was in charge of computing at Dartmouth and Carnegie Mellon, with some time in industry.
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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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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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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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Course Themes
3. Risk
Problems
Over budget Late
Does not work
Never used
Does the wrong thing Needs change
Users dislike to use itetc.
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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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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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Variety of Software Products
Examples?
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Variety of Software Products
Examples
Real time: air traffic control Embedded systems: digital camera, GPSData processing: telephone billing, pensionsInformation systems: web sites, digital librariesSensors: weather dataSystem software: operating systems, compilersCommunications: routers, mobile telephonesOffices: word processing, video
conferencesScientific: simulations, weather forecastingGraphical: film making, design etc., etc., etc., ....
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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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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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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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Professional Responsibility
Organizations put trust in software developers:
• Competence: Software that does not work effectively can destroy an organization.
• Confidentiality: Software developers and systems administrators may have access to highly confidential information (e.g., trade secrets, personal data).
• Legal environment: Software exists in a complex legal environment (e.g., intellectual property, obscenity).
• Acceptable use and misuse: Computer abuse can paralyze an organization (e.g., the Internet worm).
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Next Steps
• Selection of projects -- read the web site.
• Form project teams.
• Read the first Chapter of Pfleeger.
