CPSC 333 SENG 311: Foundations Principles of SE

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CPSC 333 / SENG 311 Foundations / Principles
of SE

• Software Development Life-Cycle

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Agenda

• Life-cycle phases
• Products
• A simple life-cycle model

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Generic view of SE

• Definition phase what
• Requirements elicitation
• Requirements analysis
• Project planning
• Development phase how
• Software design
• Coding
• Testing
• Maintenance
• Not really different phase change happens always

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Umbrella activities

• Project management
• Quality management
• Configuration management
• Risk management
• Document preparation and production

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Agenda

• Life-cycle phases
• Products
• A simple life-cycle model

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Problem description

• Which problems exist for the customer?
• Which of those will be solved by the software
  system?
• Problems in problem descriptions
• Not precise - incomplete
• Ambiguous - superficial
• Redundant - not on target

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System requirements

• Based on problem description .... and
  communication with customer
• What functional and non-functional
  characteristics are expected from the software
  system?
• What Black box description
• User requirements describes system requirements
  from the users perspective
• Developer requirements describes system
  requirements from the developers perspective
  (contract!)

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System design

• Describes the structure of the system that
  fulfills given developer requirements
• architecture
• modules (e.g., classes, components) note in
  Pressman modules components
• module interfaces
• module requirements
• How White box description
• Module requirements further describe module
  interfaces

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Module design

• Describes the structure of a module that fulfills
  given module requirements
• Data structure
• Algorithms
• How (very detailed)

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Module code

• How can a module be realized on a concrete
  execution engine (e.g. Java) ?
• Source code
• Translation of design
• Not always straightforward

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Verification and Validation

• How can you be sure that you are doing the right
  thing? (verification)
• How can you be sure that you are doing things
  right? (validation)

• Checks if you are attempting the correct goals

• Checks whether youve achieved your goals
• Testing

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V model (traditional SE)
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Agenda

• Life-cycle phases
• Products
• A simple life-cycle model

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Common misconceptions about the software process

• We must start with firm requirements
• The problems are technical
• We need better people
• Software management is different

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Process models

• Describe development strategy encompassing
• process
• methods
• tools
• Bring order into chaotic activity
• Assist in controlling and coordination of SE
  projects

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The linear sequential model (Waterfall model)
requirements document
design document
source code
used system
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Problems with the linear sequential model

• Real projects rarely follow a sequential flow
• Stating all requirements at the beginning of a
  project is difficult
• Customer must have patience
• Applicable for projects that are well understood

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Other process models

• Later in the course
• In general
• Phases always present (requirements, design,
  etc.) not always explicit
• Ordering and overlap differ
• Products differ
• Well use Extreme Programming (XP)

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Summary

• Software development involves various phases such
  as design and testing
• Process tells us order overlap of phases,
  what products are generated
• Simplistic waterfall model doesnt work
• Reading Pressman, sect. 2.1, 2.3, 2.4

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Were Available!

• Questions?
• if you have any questions about contents of this
  lecture or other course-related issues, please
  come by during our office hours, or send us email
• Dr. Joshua MTW, 12-1pm, ICT 548
• joshuar_at_cpsc.ucalgary.ca
• Dr. Walker WF, 1-2pm, ICT 546
• rwalker_at_cpsc.ucalgary.ca