16 System Design Concepts

What is System Design?

System design is the process of defining the architecture, components, modules, interfaces, and data flow of a software system to meet certain business requirement or specific requirements. It focuses on creating scalable, efficient, and reliable systems by making informed decisions about infrastructure, data management, service communication, and performance optimization. System design is a critical skill for building real-world applications, particularly those expected to handle large amounts of data, traffic, or users.

1. Caching

Caching is an essential technique in system design for storing copies of frequently accessed or computationally expensive data in a high-speed storage location (cache). By serving data from cache instead of fetching it from the database, system performance is significantly improved, response time is reduced, and backend load is minimized.

2. Database Sharding

Database sharding is a type of horizontal partitioning where large datasets are split into smaller parts called shards. Sharding is an effective solution for applications with large data requirements and high read/write workloads, as shards are distributed across different servers or instances.

3. Load Balancing

Load balancing distributes incoming requests or workloads across multiple servers to maximize performance and ensure high availability. It prevents any single server from being overwhelmed. Types:

• Static: Uses fixed rules like Round Robin.
• Dynamic: Adapts to real-time conditions using metrics like least connections or response time.

4. Messaging Queues

A message queue is a messaging component that temporarily stores messages, enabling asynchronous communication between services. It decouples producers and consumers, ensures reliable delivery, and smooths traffic spikes.

5. CDN (Content Delivery Network)

A CDN is a distributed network of servers that caches and delivers web content and resources based on user location. This reduces latency, improves load times, and enhances user experience.

6. API Gateway

An API Gateway is placed between clients and backend services. It serves as a single entry point for client requests, managing and routing them to the appropriate backend systems.

7. CAP Theorem

The CAP theorem states that in a distributed system, only two of the three properties can be achieved simultaneously: Consistency, Availability, and Partition Tolerance.

• Consistency: All nodes return the same, most recent data.
• Availability: The system remains operational and responsive at all times.
• Partition Tolerance: The system continues to function despite network failures or delays.

8. Replication

Replication involves copying and sharing data across multiple databases to improve reliability and fault tolerance. Typically, a master database replicates data to one or more slave databases.

9. Indexing

Indexing enhances database query performance. Instead of scanning an entire table, indexing allows direct access to the specific row or location, optimizing queries and reducing response time.

10. Latency

Latency is the time taken by a request to travel from its source to destination and back. It is a key metric in measuring system performance and responsiveness.

11. Fault Tolerance

Fault tolerance is the ability of a system to continue operating despite failures or errors in one or more services. It is often achieved through redundancy, replication, and auto-recovery mechanisms.

12. Microservices

Microservices architecture divides applications into small, independent services, each responsible for a specific business function. This improves reliability, scalability, and flexibility, as failure in one microservice doesn’t bring down the entire system.

13. WebSocket

WebSocket is a protocol that enables two-way communication between client and server over a single persistent TCP connection. It supports real-time data exchange, making it ideal for applications requiring live updates.

14. Relational / SQL Databases

SQL databases organize data into structured tables with predefined schemas and use SQL to query them. Examples include PostgreSQL and MySQL.

15. Non-Relational / NoSQL Databases

NoSQL databases are schema-less and store data in flexible formats such as key-value pairs or JSON. Examples include MongoDB, Redis, and Cassandra.

16. API (Application Programming Interface)

An API is a set of rules or protocols that allow different technologies to communicate. Think of an API as a waiter: the client gives the order (request), the waiter takes it to the kitchen (server), and then delivers the food (response) back to the client.