1.1 Introduction to Software Engineering

• Defining Software

  Software is:

  1. Instructions (computer programs): that when executed provide desired features, function, and performance
  2. Data structures: that enable the programs to adequately manipulate information.
  3. Documentation: that describes the operation and use of the programs
• What is Software?

  • Software is developed or engineered it is not manufactured in the classical sense
  • Software doesn't "wear out“ it deteriorates
  • Although the industry is moving toward component-based construction, most software continues to be custom-built.
• Software Application Domains

  • System software
  • Application software
  • Engineering/Scientific software
  • Embedded software
  • Product-line software
  • Web/Mobile applications
  • AI software (robotics, neural nets, game playing)
• Legacy Software

  Why must software change ?

  • ADAPTED to meet the needs of new computing environments or technology
  • ENHANCED to implement new business requirements
  • EXTENDED to make it interoperable with other more modern systems or databases
  • RE-ARCHITECTED to make it viable within a network environment
• Defining the Discipline

  Software Engineering (IEEE Definition):

  1. The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software
  2. The study of approaches as in (1)
• Software Engineering Layers (Top down)

  1. Tools
  2. Methods
  3. Process
  4. A quality focus
• Framework Activities

  • Communication
  • Planning
  • Modeling: Analysis of requirements, Design
  • Construction: Code generation, Testing
  • Deployment
• Umbrella Activities

  • Software project tracking and control
  • Risk management
  • Software quality assurance
  • Technical reviews
  • Measurement
  • Software configuration management
  • Reusability management
  • Work product preparation and production
• Process Difference Requiring Adaptation

  • Flow of activities, actions, and tasks and their interdependencies
  • Degree to which actions and tasks are defined within each framework activity
  • Degree to which work products are identified and required
  • How quality assurance activities are applied
  • How project tracking and control activities are applied
  • Degree of detail and rigor with which the process is described
  • Degree to which the customer and other stakeholders are involved with the project
  • Level of autonomy given to the software team
  • Degree to which team organization and roles are prescribed
• The Essence of Practice

  Polya suggests:

  1. Understand the problem (communication and analysis)
  2. Plan a solution (modeling and software design)
  3. Carry out the plan (code generation)
  4. Examine the result for accuracy (testing and quality assurance).
• Hooker’s General Principles

  1. The Reason It All Exists – provide value to users
  2. KISS (Keep It Simple, Stupid!) – design simple as it can be
  3. Maintain the Vision – clear vision is essential
  4. What You Produce, Others Will Consume
  5. Be Open to the Future - do not design yourself into a corner
  6. Plan Ahead for Reuse – reduces cost and increases value
  7. Think! – placing thought before action produce results
• Every software project is precipitated by some business need

  • the need to correct a defect in an existing application
  • the need to the need to adapt a ‘legacy system’ to a changing business environment
  • the need to extend the functions and features of an existing application
  • the need to create a new product, service, or system