CS322 Week 3

1
CS322 Week 3

• Software requirements
• feasibility study, trouble of natural
  languages
• View-point oriented analysis all angles
• data src, repr, reciever of services
• use-case diagrams
• System models
• 1. Data Flow diagram notations
• special nature hierarchies

2

• Relational modeling Entity-Relation diagram
  (UML)
• 1-m, m-n, 1-1, entity, relation, arrow
  (angular,
• rounded), subclass isa, key, weak entity
• foundation of database design,
• briefing of normal forms 1st, 2nd, 3rd
• motivations more examples

3

• Finite state machine (FSM) UML, state diagram,
  state/transition/pred
• regular language
• recognize patterns
• binary number even remainder over 5
• Petri-Net formal method (math), active research
  tools (Internet, os, )
• motivation system resources/dynamics
• bankers paradox
• transition, state, tokens, firing

4

• Jackson System Development (JSD)
• vanguard of OOA/FP era
• identify entities/obj and functionalities
• organize entity/func by three notations
• NL paragraphs for each rectangle
• e.g., elevator control system library system
• Two formal methods (read only) general purpose
  AI impossible rats eye common sense modeling
• Z-scheme use math logic set theory
• elevator example Button
• Button car_B U flr_B car_B \intersect
  flr_B\empty
• pushed_button pushed_button U Button?
• ?input, !output, new state and logic
  operators

5

• Algebraic approach ADT (DoD ADA)
• 1. signature defining interface syntax c
  class prototype ,
• type func(input types/names..)
• 2. axioms define semantics of the new system
• example Integer list create/cons/head/length/t
  ail
• a touch of functional programming
• Pros and cons of formal methodologies