Software design
✅ 1. What is Software Design?
📌 Definition:
Software Design is the process of defining the architecture, components, modules, interfaces, and data of a software system to satisfy specified requirements.
💡 In simple terms: Software design is the planning phase that shapes how the software will be built to ensure it meets user and business needs.
🎯 2. Why is Software Design Important?
Reason
Benefit
Guides development
Provides a clear plan for developers to follow.
Improves quality
Ensures system is scalable, secure, and efficient.
Reduces risks and errors
Identifies potential issues early.
Facilitates communication
Aligns team understanding of system structure.
Saves time and cost
Avoids costly rework and design flaws.
✅ 3. Key Activities in Software Design
Activity
Description
Understand requirements
Analyze and interpret system needs.
Define system architecture
Determine overall structure and technology stack.
Design components and modules
Identify how the system will be broken into parts.
Specify interfaces and data flow
Define how components interact and exchange data.
Consider non-functional requirements
Address performance, security, usability, etc.
✅ 4. Levels of Software Design
Level
Description
Focus
1. High-Level Design (HLD)
Architectural design showing system structure.
Major components, technologies, data flow.
2. Low-Level Design (LLD)
Detailed design of components and modules.
Class diagrams, algorithms, interface details.
📌 4.1 High-Level Design (HLD) Includes:
System architecture diagram.
Database design.
Technology stack selection.
Main components/modules and their responsibilities.
Interaction between external systems.
Example: Diagram showing the relationship between a web app, database, and external APIs.
📌 4.2 Low-Level Design (LLD) Includes:
Class diagrams and object models.
Detailed workflows.
Data structures and algorithms.
Component interaction details.
Example: UML diagram showing class relationships in a shopping cart system.
✅ 5. Key Software Design Principles
Principle
Description
Modularity
Break system into manageable, independent parts.
Encapsulation
Hide internal details; expose only what is necessary.
Separation of Concerns
Each part should handle a distinct responsibility.
Single Responsibility Principle (SRP)
Every module/class should have one responsibility.
Reusability
Design components for reuse in different contexts.
Scalability
Design to handle growth in users/data.
Maintainability
Easy to update, fix, and extend.
Performance and Security
Ensure efficient, safe operations.
✅ 6. Common Software Design Models & Diagrams
Model/Diagram
Purpose
Use Case Diagram
Shows system functionality from user perspective.
Class Diagram
Defines classes, attributes, methods, and relationships.
Sequence Diagram
Interaction flow between system components over time.
Component Diagram
Visualizes components and dependencies.
Entity-Relationship Diagram (ERD)
Models database schema and relationships.
State Diagram
Shows different states of an object and transitions.
✅ 7. Tools Used for Software Design
Purpose
Tools
Diagramming and Modeling
Lucidchart, Microsoft Visio, Draw.io, Creately.
UML and Architecture Diagrams
StarUML, Enterprise Architect, Gliffy.
Wireframing and Prototyping
Figma, Balsamiq, Adobe XD.
Code-level Design
Visual Studio, JetBrains IDEs, Eclipse.
✅ 8. Role of Business Analyst in Software Design
Activity
BA's Role
Bridge between business and technical teams
Ensure that design meets business needs.
Validate design decisions
Confirm that architecture supports requirements.
Participate in design discussions
Clarify requirements, suggest improvements.
Review diagrams and models
Ensure completeness and correctness.
Support during prototyping
Provide feedback on initial designs and mockups.
✅ 9. Example of Software Design for an E-commerce System
Component
Design Consideration
User Interface (UI)
Responsive design, user-friendly navigation.
Product Catalog
Organized categories, search/filter features.
Shopping Cart Module
Add/remove items, manage quantities.
Payment Gateway Integration
Secure, support multiple payment methods.
Order Management
Track order status, history.
Database Design
Store user, product, order data efficiently.
✅ 10. Summary of Software Design
Aspect
Explanation
Definition
Process of planning the software system structure.
Levels
High-Level Design (HLD), Low-Level Design (LLD).
Key Principles
Modularity, encapsulation, reusability, scalability.
Tools
Lucidchart, Visio, Figma, UML tools.
Role of BA
Ensure alignment between business needs and technical design.
Last updated