CHAPTER 1 – INTRODUCTION TO SOFTWARE ENGINEERING
2005 McGraw-Hill Higher Education
http://highered.mcgraw-hill.com/sites/0072853182/student_view0/chapter1/chapter_summary.html
Overview
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Software is designed and built by software engineers.
Software is used by virtually everyone in society.
Software engineers have a moral obligation to build reliable software that does no harm to
other people.
Software engineers view "software" as being made up of the programs, documents, and
data.
Software users are only concerned with whether or not software products meet their
expectations and make their tasks easier to complete.
Important Questions for Software Engineers
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Why does it take so long to get software finished?
Why are development costs so high?
Why can't we find all errors before we give the software to our customers?
Why do we continue to have difficulty in measuring progress as software is being
developed?
Software
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Software is both a product and a vehicle for delivering a product (information).
Software is engineered not manufactured.
Software does not wear out, but it does deteriorate.
Currently, most software is still custom-built.
Software Application Types
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System software
Application software
Embedded software
Engineering/Scientific software
Product software
Web Applications
Artificial intelligence software
New Software Challenges
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Ubiquitous computing
o Creating software to allow machines of all sizes to communicate with each other
across vast networks
Netsourcing
o Architecting simple and sophisticated applications that benefit targeted end-user
markets worldwide
Open Source
o Distributing source code for computing applications so customers can make local
modifications easily and reliably
New economy
o Building applications that facilitate mass communication and mass product
distribution using evolving concepts
Legacy software
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Many programs still provide a valuable business benefit, even though they are one or even
two decades old.
These programs must be maintained and this creates problems because their design is often
not amenable to change.
Software Evolution
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Process by which programs change shape, adapt to the marketplace, and inherit
characteristics from preexisting programs
Law of continuing change
o Systems must be continually adapted or they become progressively unsatisfactory
Law of increasing complexity
o As system evolves its complexity increases unless work is done to reduce the
complexity
Law of self-regulation
o System evolution is self-regulating with its process and product measures following
near normal distributions
Law of conservation of Organizational Stability
o Average effective global activity rate for an evolving systems is invariant over the
product lifetime
Law of conservation of familiarity
o As system evolves all stakeholders must maintain their mastery of its content and
behavior to achieve satisfactory evolution
Law of continuing growth
o Functional content of system must be continually increased to maintain user
satisfaction over its lifetime
Law of declining quality
o System quality will appear to decline unless the system is rigorously maintained
and adapted to environment changes
Feedback system law
o System evolution processes must be treated as multi-level, multi-loop, multi-agent
feedback systems to achieve significant improvement
Software Myths
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Still believed by many managers and practitioners
Insidious because they do have elements of truth
Every practitioner and manager should understand the reality of the software business.
Software Creation
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Almost every software project is precipitated by a business need (e.g., correct a system
defect, adapt system to changing environment, extend existing system, create new system)
Many times an engineering effort will only succeed if the software created for the project
succeeds
The market will only accept a product that has the software embedded when it meets the
customer's stated or unstated needs