High-Level Design (HLD)

About

High-Level Design, often referred to as macro-level design, provides an overview of the system architecture and design. It focuses on the big picture and outlines the overall structure and organization of the system.

HLD is like the blueprint of a building. It provides an overall picture of what the system will look like and how it will function without going into the finer details.

Key Aspects

1. System Architecture: Defines the overall architecture of the system, including its main components, their interactions, and how they fit together.

2. Modules and Components: Identifies the major modules and components within the system and their relationships.

3. Data Flow: Describes the flow of data between different parts of the system.

4. Technology Stack: Specifies the technologies, frameworks, and platforms to be used.

5. Interfaces: Defines the external interfaces, including APIs, user interfaces, and communication protocols.

6. Non-Functional Requirements: Addresses performance, scalability, security, and other non-functional aspects.

Purpose

• Provides a blueprint for the system architecture.

• Facilitates communication among stakeholders by providing a high-level view.

• Serves as a foundation for detailed design and implementation.

Example of a web-based e-commerce application

• System Architecture: Three-tier architecture with presentation, business logic, and data layers.

• Modules: User management, product catalog, shopping cart, order processing, payment gateway.

• Data Flow: User data flows from the presentation layer to the business logic layer and then to the data layer.

• Technology Stack: Frontend (React.js), Backend (Spring Boot), Database (MySQL), Hosting (AWS).

• Interfaces: RESTful APIs for communication between frontend and backend, payment gateway API.

• Non-Functional Requirements: High availability, scalability, security (SSL/TLS), performance (low latency).