CS 310 Software Engineering

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CS 310 Software Engineering

• Professor C. Shilepsky
• Spring 2002
• httm//aurora.wells.edu/ccs/310/cs310.htm
• Chapter 1
• Define software engineering and explain its
  importance
• Professional and ethical responsibility

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Software engineering-importance

• More and more systems are software controlled
• The economies of ALL developed nations depend on
  software
• Software expenditures represents a significant
  fraction of GNP in all developed countries
• Software is consistently late, over budget, and
  buggy. Why?

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1.1.1 What is software

• Generic products
• Stand-alone systems which are produced by a
  development organization and sold on the open
  market to any customer
• Bespoke (customized) products
• Systems which are commissioned by a specific
  customer and developed specially by some
  contractor
• Most software expenditure is on generic products
  but most development effort is on bespoke systems
• Current emphasis is on embedded or adapted COTS
  (commercial-off-the-shelf-software)

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1.1.2 What is software engineering

• The systematic, disciplined, and quantifiable
  approach to the development, operation,
  maintenance, and retirement of software
• It is not about programming, rather everything
  that goes into developing large systems.
• It is about managing complexity how do people
  build a system whose complexity exceeds the
  capacity of any one individual to understand it

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1.1.3, 1.1.4 Difference between CS, SE, and
system engineering

• Computer science theories and models that
  underlie computers
• e.g. data structures, discrete math, analysis of
  algorithms, ...
• Software engineering how to build a software
  system. CS theory not enough.
• e.g. flight-control software
• System engineering how to build a complex system
  that may include software
• e.g. an airplane

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1.1.5 software process

• Structured set of activities required to develop
  a software system
• Specification (what are the requirements)
• Development (design and code)
• Validation
• Evolution
• Activities vary depending on the organization
  and the type of system being developed
• 1.1.6 software process model - later

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1.17 Software engineering costs
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1.1.8 Software engineering methods

• Approaches to development
• CS 132 methods
• functional decomposition
• object-oriented programming
• Software engineering methods often integrated to
  cover the whole process
• Some are a bit like religion

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1.1.9 Computer aided software engineering (CASE)

• Tools to assist development
• We are familiar with the C development
  environment which has good built-in support
• There is more.

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1.1.10 Software product attributes

• Maintainability
• It should be possible for the software to evolve
  to meet changing requirements
• Dependability
• The software should not cause physical or
  economic damage in the event of failure
• Efficiency
• The software should not make wasteful use of
  system resources
• Usability
• Software should have an appropriate user
  interface and documentation

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1.1.11 Software engineering challenges

• Legacy systems
• It is difficult to maintain and update old
  systems
• Heterogeneity
• Systems need to operate on different hardware in
  different environments
• Delivery
• It takes longer to build a good system than
  customers want to allow.
• What else?

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1.2 Professional and ethical responsibilty

• What do these mean? Have you ever run into a
  question with one of them?
• Confidentiality
• Competence
• Intellectual property rights
• Computer misuse

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Code of ethics - principles

• 1. PUBLIC
• Software engineers shall act consistently with
  the public interest.
• 2. CLIENT AND EMPLOYER
• Software engineers shall act in a manner that is
  in the best interests of their client and
  employer consistent with the public interest.
• 3. PRODUCT
• Software engineers shall ensure that their
  products and related modifications meet the
  highest professional standards possible.

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Code of ethics - principles

• JUDGMENT
• Software engineers shall maintain integrity and
  independence in their professional judgment.
• 5. MANAGEMENT
• Software engineering managers and leaders shall
  subscribe to and promote an ethical approach to
  the management of software development and
  maintenance.
• 6. PROFESSION
• Software engineers shall advance the integrity
  and reputation of the profession consistent with
  the public interest.

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Code of ethics - principles

• 7. COLLEAGUES
• Software engineers shall be fair to and
  supportive of their colleagues.
• 8. SELF
• Software engineers shall participate in lifelong
  learning regarding the practice of their
  profession and shall promote an ethical approach
  to the practice of the profession.

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Ethical dilemmas

• Disagreement in principle with the policies of
  senior management
• Your employer acts in an unethical way and
  releases a safety-critical system without
  finishing the testing of the system
• Participation in the development of military
  weapons systems or nuclear systems
• What would you do?
• Other examples?