Complete System Design Guide: Scalability, Networking, Databases, Web Communication & Messaging

Vertical Scaling vs. Horizontal Scaling

• Vertical Scaling (Scaling Up): Upgrading the existing server by adding more CPU, RAM, or storage. It is simpler but has hardware limits.

• Horizontal Scaling (Scaling Out): Adding more servers to distribute the load. It improves fault tolerance and scalability but requires load balancing.

Networking and Distribution

Load Balancers

• Distribute traffic across multiple servers to ensure no single server is overwhelmed.

• Can be software-based (Nginx, HAProxy) or hardware-based.

• Types: Round-robin, Least Connections, IP Hash, etc.

Content Delivery Networks (CDN)

• A network of distributed servers that cache content closer to users to reduce latency.

• Examples: Cloudflare, Akamai, AWS CloudFront.

Caching

• Stores frequently accessed data to reduce database queries and improve speed.

• Types: Client-side (browser cache), Server-side (Redis, Memcached), CDN caching.

IP Address

• A unique identifier assigned to each device on a network.

• Types: IPv4 (e.g., 192.168.1.1), IPv6 (e.g., 2001:db8::ff00:42:8329).

TCP/IP

• TCP (Transmission Control Protocol): Ensures reliable, ordered, and error-checked delivery.

• IP (Internet Protocol): Handles addressing and routing packets.

Domain Name System (DNS)

• Converts human-readable domain names (e.g., google.com) into IP addresses.

• Works with caching to speed up lookups.

Web Communication

HTTP

• Protocol for web communication. Uses request methods like GET, POST, PUT, DELETE.

• Stateless, meaning each request is independent.

REST

• Representational State Transfer (REST) is an architectural style for APIs.

• Uses stateless HTTP with resources identified by URLs.

• Responses often use JSON or XML.

GraphQL

• A query language for APIs that allows clients to request only the data they need.

• Flexible compared to REST but can be complex.

gRPC

• A high-performance, language-neutral framework for RPC (Remote Procedure Calls).

• Uses Protocol Buffers (protobuf) instead of JSON for efficiency.

WebSockets

• A bi-directional, persistent connection between client and server.

• Used for real-time applications like chat apps and live notifications.

Databases and Storage

SQL

• Structured Query Language for relational databases like PostgreSQL, MySQL, SQL Server.

• Uses structured schemas and tables.

ACID

• Ensures database transactions are Atomic, Consistent, Isolated, Durable (ACID).

• Prevents issues like data corruption.

NoSQL

• Non-relational databases like MongoDB, Cassandra, DynamoDB.

• Suitable for unstructured data and high scalability.

Sharding

• Splitting large databases into smaller partitions (shards) to improve performance.

• Each shard handles a subset of data.

Replication

• Copying data across multiple servers to improve redundancy, fault tolerance, and read performance.

• Types: Master-Slave, Master-Master.

CAP Theorem

• Consistency, Availability, Partition Tolerance—a distributed system can only guarantee two out of three.

• CP (Consistency + Partition Tolerance): MongoDB

• AP (Availability + Partition Tolerance): Cassandra

Messaging and Queues

Message Queues

• Asynchronous communication between services using a queue.

• Prevents system overload and improves scalability.

• Examples: Kafka, RabbitMQ, AWS SQS.

Let me know if you need further refinements! 🚀