Architecture and Design 101: High-Level Design vs Low-Level Design
System design defines the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements. It involves both high-level and low-level design and is a crucial phase in the development lifecycle of software systems.
Key Aspects of System Design
- Architecture: establishes the overall structure and organization of the system, defining how different components interact.
- Components: identifies and specifies the individual parts of the system, including software modules and hardware elements.
- Interfaces: defines how different components communicate and interact with each other and with external systems.
- Data Flow: Describes how data moves through the system and between components, ensuring proper data handling and storage.
- Technology Stack: Chooses the appropriate technologies, frameworks, and tools that will be used in the development and deployment of the system.
- Non-functional Requirements: Addresses performance, scalability, security, reliability, and other qualities that affect the system’s usability and effectiveness.
- User Experience (UX): Considers how users will interact with the system, focusing on usability and accessibility.
In this article, we would like to go over High-Level Design (HLD) and Low-Level Design (LLD).
High-Level Design (HLD)
HLD outlines the overall architecture and the main components that will make up the system. It focuses on what the system will do and how the components interact with each other.
Key Aspects:
- Architecture Overview: Defines the system architecture, including software and hardware.
- Key Modules: Lists the major modules and their interactions.
- Data Flow: This describes the data flow across different modules and systems.
- Interfaces: Details the external interfaces, including APIs and communication protocols.
- System Integration: Explains how different systems and subsystems will integrate.
- Technology Stack: Specifies the technologies, platforms, and frameworks to be used.
- Non-functional Requirements: cover aspects like performance, scalability, reliability, and security.
Output: The HLD document usually includes diagrams like system context diagrams, component diagrams, and interaction diagrams.
Low-Level Design (LLD)
The LLD focuses on the internal details of the components and modules identified in the HLD. It describes how each component will be implemented.
Key Aspects:
- Detailed Component Design: Specifies the design of individual components and modules in detail.
- Class Diagrams: Defines classes, methods, attributes, and relationships.
- Database Design: Details the database schema, including tables, indexes, and relationships.
- Algorithms and Logic: Specifies algorithms, data structures, and detailed logic for the system’s functionality.
- State Diagrams: This describes the state transitions for state-dependent components.
- User Interface Design: Provides wireframes or mockups for user interfaces, if applicable.
- Error Handling and Logging: Outlines strategies for handling errors and logging events.
Output: The LLD document includes class diagrams, sequence diagrams, state diagrams, and detailed descriptions of the design and implementation.
Differences Between HLD and LLD
- Scope: HLD covers the system’s overall architecture, while LLD delves into the detailed design of individual components.
- Abstraction Level: HLD is more abstract and conceptual; LLD is detailed and specific.
- Audience: HLD is often intended for stakeholders and project managers to understand the system architecture, while LLD is for developers and engineers who will implement the system.
That’s all for today!
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