HCI - CHAPTER 5

• Software Engineering


  A large sub discipline that addresses the management and technical issues of the development of software systems.
• Software Life Cycle


  describes the activities that take place from the initial concept formation for a software system up until its eventual phasing out and replacement.
• Fundamental feature


  it provides the structure for applying techniques to develop software systems
• Software life cycle


  is an attempt to identify the activities that occur in software development.
• 2 main parties of Development of a software product

  1. The Customer
  2. The Designer
• Customer

  a customer who is the client of the designing company
• Customer


  who is the eventual user of the system
• Waterfall Model:

  1. Requirement specification
  2. Architectural Design
  3. Detailed Design
  4. Coding and unit testing
  5. Integration and testing
  6. Operation and maintenance
• Requirements specification 


  Designer and the customer try to capture the description of what the eventual system will be expected to provide
• Requirements specification


  determining how the system will provide the expected services.
• Requirements specification


  Involves eliciting information from the customer about the work environment, or domain, in which the final product will function.
• Requirements specification


  This begins at the start of product development.
• Architectural Design


  Concentrates on how the system provides the services expected from it.
• Architectural design


  First activity - high level decomposition of the system info components, architecture design performs this decomposition.
• Detailed Design


  a refinement of the component description provided by the architectural design
• Detailed design


  behavior implied by the higher -level description must be preserved in the more detailed description.
• Language used for the detailed design must allow some analysis of the design in order to assess its properties.
• Detailed design


  Keep track of the design options considered.
• Coding and Unit testing


  after coding, the component can be tested to verify that it performs correctly.
• Integration and testing


  Once enough components have been implemented and individually tested, they must be integrated as described in the architectural design.
• Integration and Testing


  further testing is done to ensure correct behavior and acceptable use of any shared resources.
• ISO 9241


  define usability of the office environment workstations.
• Integration and testing provide impetus for designers to take seriously the HCI implications of their design.
• Maintenance


  after the product release, all work on the system is considered under the category of maintenance.
• Majority of the lifetime of a product is spent in the maintenance activity.
• Maintenance


  Involves correction of errors in the system which are discovered after the release and the revision of the system to satisfy requirements that were not realized during previous development.
• Maintenance


  Provides feedback to all the other activities in the life cycle.
• Waterfall Model


  What model is this?

  
• Interactive System


  are designed to enable communication between the system and the user.
• Interactive system concerned with:

  1. Designing interactive systems to support human activities
  2. Applying usability engineering techniques to evaluate the effectiveness and appropriateness of the design.
• Goals of Interactive design:

  1. Develop usable products
  2. Involve users in the design process
• Usability


  means easy to learn, effective to use and provide an enjoyable experience.
• Usability Engineering


  the ultimate test of usability based on measurement of user experience.
• Usability Engineering


  demands that specific usability measures be made explicit as requirements.
• Usability specification:

  1. usability attribute/principle
  2. measuring concept
  3. measuring method
  4. now level/worst case/planned level/best case
• Usability Engineering Problems:

  1. Usability specification requires level of detail that may not be
  2. possible early in design satisfying a usability specification
  3. does not necessarily satisfy usability
• Part of usability specification for a VCR

  Attribute: Backward recoverability
• Part of usability specification for a VCR

  Measuring concept: Undo and erroneous programming sequence
• Part of usability specification for a VCR

  Measuring method: Number of explicit user actions to undo current program
• Part of usability specification for a VCR

  Now level: No current product allows such an undo