مقدمة في هندسة البرمجيات (ITGS-213) - المحاضرة 6: مرحلة التصميم

Introduction to Software Engineering (ITGS-213) - Lecture 6: Design Phase

• The design phase translates user requirements into a system representation.
• This phase ensures a reliable, user-friendly system, easily maintained.
• Key design considerations include data, processing, and the user.
• The design phase is divided into architectural design, user interface design, procedural design (modular design), and data design.

Architectural Design

• This stage breaks down the system into sub-systems.
• Simplifies complex systems for easier design and developer distribution.
• Common tools include Structure Charts and Warnier-Orr Diagrams.

Procedural Design

• This stage describes each module/part of the system, previously defined in architectural design.
• Uses textual representations (like pseudocode) or flowchart-like diagrams (Structure Flow Charts).
• Other tools include Hierarchal Input-Process-Output (HIPO) diagrams, and pseudocode.

Data Design

• Transforms data analysis into database design.
• Implements data structures and relationships.
• Data Dictionary, Entity-Relationship Diagrams (ERD), are crucial tools for this phase.

User Interface Design

• Focuses on how users interact with the system.
• Key elements include input screens (forms), reports, and support tools (help).
• Programming languages and tools (Visual Basic, Delphi, Access) are used for design and integration.
• User insights and considerations are crucial to create an effective user interface.

UML Diagrams in Object-Oriented Design

• UML is the standard language for object-oriented design.
• Several UML diagrams are used:
  • Class Diagrams: Static view of the system structures and relationships
  • Activity Diagrams: Describing program flows and processes steps
  • Sequence diagrams: Shows object interactions, method calls, etc.
• Class visibility determines access to class attributes and methods (+:public, -:private, #:protected).

Class Relationships

• Different types of relationships exist between classes:
  • Association: A basic relationship between classes (e.g., Student-Enroll-Course)
  • Aggregation: A part-whole relationship. Parts can exist independently of the whole (e.g., Car-engine)
  • Composition: A stronger part-whole relationship. Parts cannot exist independently of the whole (e.g., House-Walls)
  • Generalization: A "is-a" relationship. Subclasses inherit properties from superclasses (e.g., Person - Employee - Doctor)