An introduction to software engineering, based on the first chapter of "A (Partial) Introduction to Software Engineering Practices and Methods" By Laurie Williams

1. An Introduction to
Software
Engineering
Carlos G. Gavidia (cgavidia@acm.org)

2. Topics
• Computer Science vs. Software Engineering.
• Software Engineering and other Engineering
disciplines.
• Challenges of Software Engineering.
• Software development processes.

3. An Introduction to Software Engineering
WHAT’S SOFTWARE
ENGINEERING?

4. Software: A definition
“Software Systems are perhaps the most
intricate and complex … of the things humanity
makes.”
-Fred Brooks

5. Software engineering
• Has progressed very far in a short time:
– 50 years ago, most programming were done
by Scientists trying to solve mathematical
problems.
– Today, we build monstrous systems used
everywhere.
• But, software industry is in crisis:
– A software project overshoots its schedule
by a half.
– Three quarters of all large systems are
operating failures.

6. Computer Science: A definition
“Computer science is a discipline that involves
the understanding and design of computers and
computational processes. In its most general
form it is concerned with the understanding of
information transfer and transformation.
Particular interest is placed on making
processes efficient and endowing them with
some form of intelligence.”
-CSAB

7. Engineering: A definition
“The systematic and regular application of
scientific and mathematical knowledge to the
design, construction, and operation of machines, systems,
and so on of practical use and, hence, of economic
value. Particular characteristic of engineers is that they
take seriously their responsibility for correctness,
suitability, and safety of the results of their efforts.
In this regard they consider themselves to be responsible
to their customer (including their employers where
relevant), to the users of their machines and systems, and
to the public at large.”
-Robert Baber

8. Software Engineering as Engineering
• Practical use, economic value:
– We need to determine the content and build
the best product value.
• Responsibility for correctness, suitability and
safety:
– The work you do could impact the safety,
business and well being of the customer.
• Regular application of scientific and
mathematical knowledge:
– Computer Science, psychology, economics
and management

9. Software Engineering: A Definition
“Software engineering is the application of a
systematic, disciplined, quantifiable approach to
the development, operation, and maintenance of
software; that is, the application of engineering
to software”
-IEEE

10. An Introduction to Software Engineering
A PROCESS FOR MAKING
SOFTWARE

11. Software Development Practices
• Requirements
engineering
• High-level design
• Low-level design
• Coding
• Integration
•
•
•
•
Code reviews
Testing
Maintenance
Project
management
• Configuration
management

12. Software Development Practices
• You will learn MANY software development
practices.
• You’ll find:
– A practice is good for safety-critical
software.
– Another is better for small projects.
• Engineering is about selecting the most
appropriate method for a set of circumstances.
• You can use the practices and build a software
process with them.

13. Software Development Process
The process by which user needs are translated
into a software product. The process involves
translating user needs into software
requirements, transforming the software
requirements into design, implementing the
design in code, testing the code, and sometimes
installing and checking out the software for
operational use. Note: these activities might
overlap or be performed iteratively
- IEEE

14. Software process model
Plan Driven
The cost can be
minimized by
creating detailed
plans and by
constructing and
inspecting
architecture and
design documents.
Agile
Time is spent
planning and
gathering
requirements for
small iterations
throughout the
entire lifecycle of
the project.

15. An Introduction to Software Engineering
MAKING SOFTWARE IS
HARD

16. The programmer
The programmer, like the poet, works only
slightly removed from pure thought-stuff. He
builds his castles in the air, from air, creating by
exertion of the imagination.
-Frederick Brooks

17. Software Engineering Challenges
• Tractable Medium
– The constraints of physical medium can
serve to simplify alternatives.
• Changing requirements
– It is hard for customers to express what
they want in a product.
• Schedule Optimism
– We are an optimistic crew.
• Schedule Pressure
– Every product is late before it’s even started

18. Credits
Based on:A (Partial)
Introduction to
Software Engineering
Practices and Methods
• By Laurie Williams
• Available in:
http://agile.csc.ncsu
.edu/SEMaterials/C
oursePack.pdf