Architectural and Detailed Design

📘 Architectural and Detailed Design (OOAD)

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🔹 1. Definition

In Object-Oriented Analysis and Design (OOAD):

• Architectural Design defines the overall structure of the system (high-level view).
• Detailed Design focuses on the internal design of each component (low-level view).

👉 Simple idea:

• Architecture = Big picture (how parts fit together)
• Detailed Design = Small picture (how each part works internally)

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🔹 2. Architectural Design ⭐

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🔸 2.1 Definition

Architectural Design is the process of identifying:

• Major components (modules/subsystems)
• Their relationships
• System structure

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🔸 2.2 Goals

• Define system structure
• Ensure scalability and performance
• Improve maintainability
• Support reusability

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🔸 2.3 Key Elements

Element	Description
Components	Major parts of system
Connectors	Communication between components
Interfaces	Interaction points
Configuration	Overall arrangement

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🔸 2.4 Common Architectural Styles

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🔹 1. Layered Architecture

• System divided into layers

Example Layers:

Presentation Layer
Business Logic Layer
Data Layer

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🔹 2. Client-Server Architecture

• Client requests, server responds

Example: Web applications

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🔹 3. MVC (Model-View-Controller)

• Model → Data
• View → UI
• Controller → Logic

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🔹 4. Microservices Architecture

• System divided into small independent services

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🔸 2.5 Diagram Description

• Boxes represent components
• Arrows show communication

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🔹 3. Detailed Design ⭐

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🔸 3.1 Definition

Detailed Design focuses on:

• Internal logic of classes
• Algorithms
• Data structures

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🔸 3.2 Goals

• Provide complete blueprint for coding
• Define methods and logic
• Ensure correctness

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🔸 3.3 Key Elements

Element	Description
Classes	Detailed structure
Methods	Functions
Algorithms	Step-by-step logic
Data Structures	Data organization

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🔸 3.4 Tools Used

• Class Diagrams
• Sequence Diagrams
• Activity Diagrams
• Pseudocode

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🔸 3.5 Example

Class: BankAccount
- balance
+ deposit(amount)
+ withdraw(amount)

Pseudocode:

if (balance >= amount)
   withdraw
else
   show error

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🔹 4. Difference Between Architectural & Detailed Design ⭐

Feature	Architectural Design	Detailed Design
Level	High-level	Low-level
Focus	System structure	Internal logic
Output	Architecture diagram	Class & sequence diagrams
Stage	Early design	Later design

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🔹 5. Design Process Flow

Requirements → Analysis → Architectural Design → Detailed Design → Implementation

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🔹 6. Example (Library System)

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🔹 Architectural Design:

• Modules:

  • User Interface
  • Book Management
  • Database

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🔹 Detailed Design:

Class: Book
- title
- author
+ issue()
+ return()

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🔹 7. Advantages

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🔸 Architectural Design:

• Clear system structure
• Easy scalability
• Better performance planning

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🔸 Detailed Design:

• Easy coding
• Fewer errors
• Clear logic

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🔹 8. Important Rules / Guidelines

• Keep architecture simple and modular
• Use low coupling & high cohesion
• Follow design patterns
• Ensure consistency between levels
• Document clearly

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🔹 9. Likely Exam Questions

1. Define architectural design.
2. What is detailed design?
3. Differentiate between architectural and detailed design.
4. Explain layered architecture.
5. What is MVC architecture?
6. Describe components of architectural design.
7. Explain tools used in detailed design.
8. Draw architecture of a simple system.
9. Explain design process flow.
10. Advantages of architectural design.

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🔹 10. Quick Revision Summary 🧠

• Architectural Design → Big structure of system
• Detailed Design → Internal working of components

Key Points:

• Architecture = Components + Connections
• Detailed Design = Classes + Methods + Logic

👉 Trick: "AD → Architecture then Details"

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