CP317A Software Engineering Week 3-2

Software Engineering Course Notes

• Course: CP317A Software Engineering
• Instructor: Shaun Gao, Ph.D., P.Eng.
• Topic: High-level design, part 2 - Week 3-2

Agenda

• Review week 3-1
• Race condition
• Unified Modeling Language (UML)
• UML diagrams
  • Structure diagrams (Class, Object, Package, Composite Structure, Component, Manifestation, Deployment, Network Architecture, Profile)
  • Behavior diagrams (Use Case, Activity, State Machine, Sequence, Interaction)
• Design principles (3 principles)
  • Decomposition
  • Cohesion
  • Coupling
• Summary

Race Condition

• Event-driven or distributed architectures can cause race conditions
• Race condition: undesirable situation where multiple processes try to modify the same object concurrently
• Problems: data inconsistency
• Prevention techniques: mutual exclusion, semaphores

Unified Modeling Language (UML)

• UML: general-purpose modeling language for software engineering
• Intended to visualize system designs
• Multiple UML diagram types for different purposes
• UML version 2.0 defines 13 diagrams

Design Principles

• Decomposition: Breaking down complex problems into smaller, manageable parts. (e.g., ATM example - splitting into display, balance, deposit, transfer, withdraw)
• Cohesion: How closely related the elements within a module are. High cohesion is better
• Coupling: The dependencies between software components or modules. Low coupling is better

UML: Diagram Types

• Structure Diagrams: show the static structure of the system
  • Class Diagram: depicts classes, attributes, operations, and relationships between them; Used for creating static structure
  • Object Diagram: depicts specific objects from a class diagram; Show the instances of the classes mentioned in the class diagram
  • Package Diagram: depicts how a system is composed into several packages; Shows how the system classifies and arranges each component
  • Component Diagram: depicts the software components in a system; Shows the different components in the system in a graphical representation
  • Composite Structure Diagram: graphical representation of how parts of a class structure function
  • Deployment Diagram: shows the physical deployment of components in a system
  • Manifestation Diagram: show how components execute in a system
  • Network Architecture Diagram: depicts how systems in a network interact
  • Profile Diagram: extends the UML language and notation for a specific domain or project
• Behavior Diagrams: show the system's dynamic behaviour over time
  • Use Case Diagram: model the interaction between actors/users and the system's functions. Show function of different components to the user or actor
  • State Machine Diagram: model the behavior and states of a component as it progresses through various circumstances (Example: ATM states).
  • Sequence Diagram: depicts the interaction among objects in a system; Show the communication/messages exchanged between actors over a sequence
  • Activity Diagram: model business logic with flows and actions; shows different phases within the system
  • Interaction Diagram: show interactions between objects and their interactions over a timeframe.

Additional Information

• Project Report (SDD) is the starting point for group projects
• Low-level design will be discussed next week
• Help available for group formation