- System Analysis and Design - Home
- System Analysis & Design - Overview
- Differences between System Analysis and System Design
- System Analysis and Design - Communication Protocols
- Horizontal and Vertical Scaling in System Design
- Capacity Estimation in Systems Design
- Roles of Web Server and Proxies in Designing Systems
- Clustering and Load Balancing
- System Development Life Cycle
- System Analysis and Design - Requirement Determination
- System Analysis and Design - Systems Implementation
- System Analysis and Design - System Planning
- System Analysis and Design - Structured Analysis
- System Design
- System Analysis and Design - Design Strategies
- System Analysis and Design - Software Deployment
- Software Deployment Example Using Docker
- Functional Vs. Non-functional Requirements
- Data Flow Diagrams(DFD)
- Data Flow Diagram - What It Is?
- Data Flow Diagram - Types and Components
- Data Flow Diagram - Development
- Data Flow Diagram - Balancing
- Data Flow Diagram - Decomposition
- Databases in System Design
- System Design - Databases
- System Design - Database Sharding
- System Design - Database Replication
- System Design - Database Federation
- System Design - Designing Authentication System
- Database Design Vs. Database Architecture
- Database Federation Vs. Database Sharding
- High Level Design(HLD)
- System Design - High Level Design
- System Design - Availability
- System Design - Consistency
- System Design - Reliability
- System Design - CAP Theorem
- System Design - API Gateway
- Low Level Design(LLD)
- System Design - Low Level Design
- System Design - Authentication Vs. Authorization
- System Design - Performance Optimization Techniques
- System Design - Containerization Architecture
- System Design - Modularity and Interfaces
- System Design - CI/CD Pipelines
- System Design - Data Partitioning Techniques
- System Design - Essential Security Measures
- System Implementation
- Input / Output & Forms Design
- Testing and Quality Assurance
- Implementation & Maintenance
- System Security and Audit
- Object-Oriented Approach
- System Analysis & Design Resources
- Quick Guide
- Useful Resources
- Discussion
System Design - High Level Design
Introduction
System Design is an essential phase of software development where a blueprint is created for building a robust, scalable, and maintainable system. It has two major components−
High-Level Design (HLD)− Focuses on the system's architecture, major components, and their interactions.
Low-Level Design (LLD)− Delves into the detailed implementation of the components defined in HLD.
This article focuses on High-Level Design, explaining its role in system design, key components, tools, techniques, and challenges.
In modern software engineering, systems must meet growing demands for scalability, reliability, and usability. High-Level Design lays the groundwork for creating systems that fulfill these criteria, ensuring smooth development and operations.
What is High-Level Design in System Design?
Definition
High-Level Design (HLD) provides a macro view of the system. It outlines the architecture, subsystems, modules, and how they interact. Unlike Low-Level Design, which deals with specific implementations, HLD focuses on−
The system's major components.
Communication protocols between components.
Scalability and performance considerations.
HLD often represents the "what" of a system, while LLD answers the "how."
Goals of High-Level Design
Clarity− Provide a clear and shared understanding of the system's architecture.
Direction− Guide developers by offering an architectural roadmap.
Scalability− Anticipate future growth and design for it.
Alignment− Ensure that technical decisions align with business objectives.
Key Components of High-Level Design
A well-defined High-Level Design typically includes−
System Architecture
This defines the overall structure, including−Architectural pattern− Monolithic, Microservices, Event-driven, or Serverless.
Core layers− Presentation layer, business logic layer, and data layer.
Deployment model− On-premises, cloud, or hybrid.
Subsystems and Modules
HLD breaks down the system into logical subsystems or modules. For example−E-commerce system− Modules like User Management, Order Management, and Inventory.
Data Flow
Describes how data flows across components and external systems. This includes−Input/Output specifications.
Communication protocols (e.g., HTTP, gRPC).
External integrations (e.g., APIs, message queues).
Database Design
Defines high-level database structures, such as−Choice of databases− Relational (MySQL) or NoSQL (MongoDB).
Partitioning and sharding strategies for scalability.
Non-Functional Requirements (NFRs)
Addresses aspects like−Scalability− Handle increasing load efficiently.
Availability− Minimize downtime (e.g., 99.99% uptime).
Security− Protect sensitive data.
Performance− Optimize for latency and throughput.
Interfaces and APIs
Defines interaction points between internal and external systems. For example−RESTful APIs or GraphQL endpoints.
Data formats like JSON or XML.
Principles of High-Level Design
High-Level Design must adhere to key principles to ensure a robust system−
Modularity− Divide the system into independent, loosely coupled modules to improve maintainability.
Scalability− Design to handle future growth in users, traffic, or data.
Performance− Optimize response times and minimize resource usage.
Security− Ensure components are protected from potential vulnerabilities.
Reusability− Design modules that can be reused across multiple projects.
Reliability and Fault Tolerance− Create fail-safe mechanisms to handle errors or outages gracefully.
Simplicity− Avoid over-engineering; keep the design easy to understand and implement.
The Process of High-Level Design
Creating a High-Level Design involves several steps−
Gather Requirements
Collect functional and non-functional requirements from stakeholders. For example−
Functional− User authentication, product recommendations.
Non-functional− 99.99% uptime, 200ms response time.
Choose an Architecture
Decide on an architectural pattern that best suits the requirements−
Monolithic− Suitable for small, simple systems.
Microservices− Ideal for scalability and modularity.
Event-Driven− For real-time applications like IoT.
Serverless− For event-based, cost-efficient systems.
Define Major Components
Identify and define the system's major components, such as−
Application servers.
Databases.
Load balancers.
Specify Data Flow
Map how data travels between components and external systems.
Document and Visualize
Use diagrams to represent the system design, such as−
UML diagrams (Class, Sequence, and Deployment diagrams).
Data flow diagrams.
Component diagrams.
Tools and Techniques for High-Level Design
Tools
Lucidchart− Ideal for flowcharts and architecture diagrams.
Draw.io− Free tool for creating component and data flow diagrams.
Microsoft Visio− Professional diagramming software.
Enterprise Architect− Advanced tool for UML and system modelling.
Techniques
Unified Modelling Language (UML)− Standardized visual representations.
Data Flow Modelling− Illustrate how data moves within the system.
Component-Based Design− Focus on defining reusable components.
Examples of High-Level Design
Example 1: E-Commerce Platform
Components−
Presentation Layer− Angular-based frontend.
Backend Services− Microservices using Spring Boot.
Database− Relational database for transactions, NoSQL for caching.
Load Balancer− Ensures high availability.
Data Flow−
User requests → API Gateway → Microservices → Database → Response.
Example 2: Video Streaming Service
Components−
Content Delivery− CDN for streaming content.
Recommendation Engine− Machine Learning-based personalization.
Authentication Service− OAuth2 for secure login.
Data Flow−
Video request → CDN → Backend services → Database → Response.
Common Challenges in High-Level Design
Requirement Ambiguity− Incomplete or vague requirements can lead to incorrect designs.
Scalability Trade-offs− Balancing scalability with cost and complexity.
Integration Complexity− Ensuring seamless communication between heterogeneous systems.
Over-Engineering− Avoiding unnecessary complexity in the design.
Evolving Requirements− Adapting the design to accommodate changes in requirements.
Conclusion
High-Level Design is a critical phase in system design, providing a roadmap for creating scalable, secure, and maintainable systems. By focusing on architecture, data flow, and NFRs, it ensures that the development team has a clear and shared understanding of the system.
Adhering to principles like modularity, scalability, and simplicity, while leveraging tools like UML and diagramming software, can significantly enhance the quality of your High-Level Design. A well-crafted HLD lays the foundation for a system that meets both current and future demands.