System Design
Learn System Design
Introduction to System Design
How to Learn System Design?
Functional vs. Non-functional Requirements
What are Back-of-the-Envelope Estimations?
Things to Avoid During System Design Interview
System Design Basics
Load Balancing
Introduction to Load Balancing
Load Balancing Algorithms
Uses of Load Balancing
Load Balancer Types
Stateless vs. Stateful Load Balancing
High Availability and Fault Tolerance
Scalability and Performance
Challenges of Load Balancers
API Gateway
Introduction to API Gateway
Usage of API gateway
Advantages and disadvantages of using API gateway
Key Characteristics of Distributed Systems
Scalability
Availability
Latency and Performance
Concurrency and Coordination
Monitoring and Observability
Resilience and Error Handling
Fault Tolerance vs. High Availability
Network Essentials
HTTP vs. HTTPS
TCP vs. UDP
HTTP: 1.0 vs. 1.1 vs 2.0 vs. 3.0
URL vs. URI vs. URN
Domain Name System (DNS)
Introduction to DNS
DNS Resolution Process
DNS Load Balancing and High Availability
Caching
Introduction to Caching
Why is Caching Important?
Types of Caching
Cache Replacement Policies
Cache Invalidation
Cache Read Strategies
Cache Coherence and Consistency Models
Caching Challenges
Cache Performance Metrics
CDN
What is CDN?
Origin Server vs. Edge Server
CDN Architecture
Push CDN vs. Pull CDN
Data Partitioning
Introduction to Data Partitioning
Partitioning Methods
Data Sharding Techniques
Benefits of Data Partitioning
Common Problems Associated with Data Partitioning
Proxies
What is a Proxy Server?
Uses of Proxies
VPN vs. Proxy Server
Redundancy and Replication
What is Redundancy?
What is Replication?
Replication Methods
Data Backup vs. Disaster Recovery
CAP & PACELC Theorems
Introduction to CAP Theorem
Components of CAP Theorem
Trade-offs in CAP Theorem
Examples of CAP Theorem in Practice
Beyond CAP Theorem
System Design Trade-offs in Interviews
Databases (SQL vs. NoSQL)
Introduction to Databases
SQL Databases
NoSQL Databases
SQL vs. NoSQL
ACID vs BASE Properties
Real-World Examples and Case Studies
SQL Normalization and Denormalization
In-Memory Database vs. On-Disk Database
Data Replication vs. Data Mirroring
Database Federation
Indexes
What are Indexes?
Types of Indexes
Bloom Filters
Introduction to Bloom Filters
Benefits & Limitations of Bloom Filters
Variants and Extensions of Bloom Filters
Applications of Bloom Filters
Long-Polling vs. WebSockets vs. Server-Sent Events
Difference Between Long-Polling, WebSockets, and Server-Sent Events
Quorum
Why Quorum?
What is Quorum?
Heartbeat
What is Heartbeat?
Checksum
What is Checksum?
Uses of Checksum
Leader and Follower
What is Leader and Follower Pattern?
Security
What is Security and Privacy?
What is Authentication?
What is Authorization?
Authentication vs. Authorization
OAuth vs. JWT for Authentication
What is Encryption?
What are DDoS Attacks?
Distributed Messaging System
Introduction to Messaging System
Introduction to Kafka
Messaging patterns
Popular Messaging Queue Systems
RabbitMQ vs. Kafka vs. ActiveMQ
Scalability and Performance
Distributed File Systems
What is a Distributed File System?
Architecture of a Distributed File System
Key Components of a DFS
Misc Concepts
Batch Processing vs. Stream Processing
XML vs. JSON
Synchronous vs. Asynchronous Communication
Push vs. Pull Notification Systems
Microservices vs. Serverless Architecture
Message Queues vs. Service Bus
Stateful vs. Stateless Architecture
Event-Driven vs. Polling Architecture
Quiz - System Design Fundamentals
Quiz
System Design Master Template
System Design Interviews - A step by step guide
System Design Master Template
Designing a URL Shortening Service like TinyURL
Designing a URL Shortening Service like TinyURL
Quiz - Designing URL Shortner
Designing Pastebin
Designing Pastebin
Quiz - Designing Pastebin
Designing Instagram
Designing Instagram
Quiz - Designing Instagram
Designing Dropbox
Designing Dropbox
Quiz - Designing Dropbox
Designing Facebook Messenger
Designing Facebook Messenger
Quiz - Designing Facebook Messenger
Designing Twitter
Designing Twitter
Quiz - Designing Twitter
Designing Youtube or Netflix
Designing Youtube or Netflix
Quiz - Designing Youtube
Designing Typeahead Suggestion
Designing Typeahead Suggestion
Quiz - Designing Typeahead Suggestion
Designing an API Rate Limiter
Designing an API Rate Limiter
Quiz - Designing an API Rate Limiter
Designing Twitter Search
Designing Twitter Search
Quiz - Designing Twitter Search
Designing a Web Crawler
Designing a Web Crawler
Quiz - Designing a Web Crawler
Designing Facebook’s Newsfeed
Designing Facebook’s Newsfeed
Quiz - Designing Facebook’s Newsfeed
Designing Yelp or Nearby Friends
Designing Yelp or Nearby Friends
Quiz - Designing Yelp or Nearby Friends
Designing Uber backend
Designing Uber backend
Quiz - Designing Uber backend
Designing Ticketmaster
Designing Ticketmaster
Quiz - Designing Ticketmaster
Dynamo: How to design a key value store?
Dynamo: Introduction
High-Level Architecture
Data Partitioning
Replication
Vector Clocks and Conflicting Data
The Life of Dynamo’s put() & get() Operations
Anti-entropy Through Merkle Trees
Gossip Protocol
Dynamo Characteristics and Criticism
Summary: Dynamo
Quiz: Dynamo
Mock Interview: Dynamo
Designing YouTube Likes Counter (medium)
YouTube Likes Counter
Quiz
Cassandra: How to Design a Wide-column NoSQL Database?
Cassandra: Introduction
High-level Architecture
Replication
Cassandra Consistency Levels
Gossiper
Anatomy of Cassandra's Write Operation
Anatomy of Cassandra's Read Operation
Compaction
Tombstones
Summary: Cassandra
Quiz: Cassandra
Mock Interview: Cassandra
Kafka: How to Design a Distributed Messaging System?
Messaging Systems: Introduction
Kafka: Introduction
High-level Architecture
Kafka: Deep Dive
Consumer Groups
Kafka Workflow
Role of ZooKeeper
Controller Broker
Kafka Delivery Semantics
Kafka Characteristics
Summary: Kafka
Quiz: Kafka
Mock Interview: Kafka
Chubby: How to Design a Distributed Locking Service?
Chubby: Introduction
High-level Architecture
Design Rationale
How Chubby Works
File, Directories, and Handles
Locks, Sequencers, and Lock-delays
Sessions and Events
Master Election and Chubby Events
Caching
Database
Scaling Chubby
Summary: Chubby
Quiz: Chubby
Mock Interview: Chubby
HDFS: How to Design File Storage System?
Hadoop Distributed File System: Introduction
High-level Architecture
Deep Dive
Anatomy of a Read Operation
Anatomy of a Write Operation
Data Integrity & Caching
Fault Tolerance
HDFS High Availability (HA)
HDFS Characteristics
Summary: HDFS
Quiz: HDFS
Mock Interview: HDFS
GFS: How to Design a Distributed File System Storage?
Google File System: Introduction
High-level Architecture
Single Master and Large Chunk Size
Metadata
Master Operations
Anatomy of a Read Operation
Anatomy of a Write Operation
Anatomy of an Append Operation
GFS Consistency Model and Snapshotting
Fault Tolerance, High Availability, and Data Integrity
Garbage Collection
Criticism on GFS
Summary: GFS
Quiz: GFS
Mock Interview: GFS
BigTable: How to Design a Wide Column Storage System?
BigTable: Introduction
BigTable Data Model
System APIs
Partitioning and High-level Architecture
SSTable
GFS and Chubby
Bigtable Components
Working with Tablets
The Life of BigTable's Read & Write Operations
Fault Tolerance and Compaction
BigTable Refinements
BigTable Characteristics
Summary: BigTable
Quiz: BigTable
Mock Interview: BigTable
Designing Reddit (medium)
Design Reddit
Quiz
Designing Notification Service (medium)
Designing a Notification System
Quiz
Design Google Calendar (medium)
Design Google calendar (Medium)
Quiz
Design a Recommendation System (medium)
Design a Recommendation System for Netflix
Quiz
Designing Gmail (medium)
Design Gmail
Quiz
Designing Google News (medium)
Design Google News, a Global News Aggregator System (Medium)
Quiz
Designing Unique ID Generator (medium)
Design Unique ID Generator (Easy)
Quiz
Designing Code Judging System (medium)
Design Code Judging System like LeetCode (Medium)
Quiz
Designing Payment System (hard)
Design Payment System
Quiz
Designing Flash Sale System (hard)
Design a Flash Sale for an E-commerce Site (Hard)
Quiz
Designing Reminder Alert System (hard)
Design a Reminder Alert System
Quiz
System Design Patterns
Introduction: System Design Patterns
1. Bloom Filters
2. Consistent Hashing
3. Quorum
4. Leader and Follower
5. Write-ahead Log
6. Segmented Log
7. High-Water Mark
8. Lease
9. Heartbeat
10. Gossip Protocol
11. Phi Accrual Failure Detection
12. Split Brain
13. Fencing
14. Checksum
15. Vector Clocks
16. CAP Theorem
17. PACELC Theorem
18. Hinted Handoff
19. Read Repair
20. Merkle Trees
Quiz
Load Balancer vs. API Gateway
load balancing
api gateway
microservices
high availability
+2
Load Balancer and API Gateway are two crucial components in modern web architectures, often used to manage incoming traffic and requests to web applications. While they have some overlapping functionalities, their primary purposes and use cases are distinct.
Load Balancer
- Purpose: A Load Balancer is primarily used to distribute network or application traffic across multiple servers. This distribution helps to optimize resource use, maximize throughput, reduce response time, and ensure reliability.
- How It Works: It accepts incoming requests and then routes them to one of several backend servers based on factors like the number of current connections, server response times, or server health.
- Types: There are different types of load balancers, such as hardware-based or software-based, and they can operate at various layers of the OSI model (Layer 4 - transport level or Layer 7 - application level).
Example of Load Balancer:
Imagine an e-commerce website experiencing high volumes of traffic. A load balancer sits in front of the website’s servers and evenly distributes incoming user requests to prevent any single server from becoming overloaded. This setup increases the website's capacity and reliability, ensuring all users have a smooth experience.
API Gateway
- Purpose: An API Gateway is an API management tool that sits between a client and a collection of backend services. It acts as a reverse proxy to route requests, simplify the API, and aggregate the results from various services.
- Functionality: The API Gateway can handle a variety of tasks, including request routing, API composition, rate limiting, authentication, and authorization.
- Usage: Commonly used in microservices architectures to provide a unified interface to a set of microservices, making it easier for clients to consume the services.
Example of API Gateway:
Consider a mobile banking application that needs to interact with different services like account details, transaction history, and currency exchange rates. An API Gateway sits between the app and these services. When the app requests user account information, the Gateway routes this request to the appropriate service, handles authentication, aggregates data from different services if needed, and returns a consolidated response to the app.
Key Differences:
- Focus: Load balancers are focused on distributing traffic to prevent overloading servers and ensure high availability and redundancy. API Gateways are more about providing a central point for managing, securing, and routing API calls.
- Functionality: While both can route requests, the API Gateway offers more functionalities like API transformation, composition, and security.
Is it Possible to Use a Load Balancer and an API Gateway Together?
Yes, you can use a Load Balancer and an API Gateway together in a system architecture, and they often complement each other in managing traffic and providing efficient service delivery. The typical arrangement is to place the Load Balancer in front of the API Gateway, but the actual setup can vary based on specific requirements and architecture decisions. Here’s how they can work together:
Load Balancer Before API Gateway
- Most Common Setup: The Load Balancer is placed in front of the API Gateway. This is the typical configuration in many architectures.
- Functionality: The Load Balancer distributes incoming traffic across multiple instances of the API Gateway, ensuring that no single gateway instance becomes a bottleneck.
- Benefits:
- High Availability: This setup enhances the availability and reliability of the API Gateway.
- Scalability: Facilitates horizontal scaling of API Gateway instances.
- Example: In a cloud-based microservices architecture, external traffic first hits the Load Balancer, which then routes requests to one of the several API Gateway instances. The chosen API Gateway instance then processes the request, communicates with the appropriate microservices, and returns the response.
Load Balancer After API Gateway
- Alternative Configuration: In some cases, the API Gateway can be placed in front of the Load Balancer, especially when the Load Balancer is used to distribute traffic to various microservices or backend services.
- Functionality: The API Gateway first processes and routes the request to an internal Load Balancer, which then distributes the request to the appropriate service instances.
- Use Case: Useful when different services behind the API Gateway require their own load balancing logic.
Combination of Both
- Hybrid Approach: Some architectures might have Load Balancers at both ends – before and after the API Gateway.
- Reasoning: External traffic is first balanced across API Gateway instances for initial processing (authentication, rate limiting, etc.), and then further balanced among microservices or backend services.
Conclusion:
In a complex web architecture:
- A Load Balancer would be used to distribute incoming traffic across multiple servers or services, enhancing performance and reliability.
- An API Gateway would be the entry point for clients to interact with your backend APIs or microservices, providing a unified interface, handling various cross-cutting concerns, and reducing the complexity for the client applications.
In many real-world architectures, both of these components work together, where the Load Balancer effectively manages traffic across multiple instances of API Gateways or directly to services, depending on the setup.
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