Tag Archives: coding interviews

Want to Get Better at System Design Interviews? Here’s How to Prepare

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System design interviews can be daunting due to their complexity and the vast knowledge required to excel. Whether you’re a recent graduate or a seasoned engineer, preparing for these interviews necessitates a well-thought-out strategy and access to the right resources. In this article, I’ll guide you to navigate the system design landscape and equip you to succeed in your upcoming interviews.

Start with the Basics

“Web Scalability for Startup Engineers” by Artur Ejsmont — This book is recommended as a starting point for beginners in system design.

“Designing Data-Intensive Applications” by Martin Kleppmann is described as a more in-depth resource for those with a basic understanding of system design.

It’s essential to establish a strong foundation before delving too deep into a subject. For beginners, “Web Scalability for Startup Engineers” is an excellent resource. It covers the basics and prepares you for more advanced concepts. After mastering the fundamentals, “Designing Data-Intensive Applications” by Martin Kleppmann will guide you further into data systems.

Microservices and Domain-Driven Design

“Building Microservices” by Sam Newman — Focuses on microservices architecture and its implications in system design.

Once you are familiar with the fundamentals, the next step is to explore the intricacies of the microservices architectural style through “Building Microservices.” To gain a deeper understanding of practical patterns and design principles, “Microservices Patterns and Best Practices” is an excellent resource. Lastly, for those who wish to understand the philosophy behind system architecture, “Domain-Driven Design” is a valuable read.

API Design and gRPC

“RESTful Web APIs” by Leonard Richardson, Mike Amundsen, and Sam Ruby provides a comprehensive guide to developing web-based APIs that adhere to the REST architectural style.

In the present world, APIs serve as the main connecting point of the internet. If you intend to design effective APIs, a good starting point would be to refer to “RESTful Web APIs” by Leonard Richardson and his colleagues. Moreover, if you are exploring the Remote Procedure Call (RPC) genre, particularly gRPC, then “gRPC: Up and Running” is a comprehensive guide.

Preparing for the Interview

“System Design Interview — An Insider’s Guide” by Alex Xu is an essential book for those preparing for challenging system design interviews.

It offers a comprehensive look at the strategies and thought processes required to navigate these complex discussions. Although it is one of many resources candidates will need, the book is tailored to equip them with the means to dissect and approach real interview questions. The book blends technical knowledge with the all-important communicative skills, preparing candidates to think on their feet and articulate clear and effective system design solutions. Xu’s guide demystifies the interview experience, providing a rich set of examples and insights to help candidates prepare for the interview process.

Domain-Specific Knowledge

Enhance your knowledge in your domain with books such as “Kafka: The Definitive Guide” for Distributed Messaging and “Cassandra: The Definitive Guide” for understanding wide-column stores. “Designing Event-Driven Systems” is crucial for grasping event sourcing and services using Kafka.

General Product Design

Pay attention to product design in system design. Books like “The Design of Everyday Things” and “Hooked: How to Build Habit-Forming Products” teach user-centric design principles, which are increasingly crucial in system design.

Online Resources

The internet is a goldmine of information. You can watch tech conference talks, follow YouTube channels such as Gaurav Sen’s System Design Interview and read engineering blogs from companies like Uber, Netflix, and LinkedIn.

System design is an iterative learning process that blends knowledge, curiosity, and experience. The resources provided here are a roadmap to guide you through this journey. With the help of these books and resources, along with practice and reflection, you will be well on your way to mastering system design interviews. Remember, it’s not just about understanding system design but also about thinking like a system designer.

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System Design 101: Design a Twitter-Like Platform

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In this article, I talk about how to build a system like Twitter. I focus on the problems that come up when very famous people, like Elon Musk, tweet and many people see it at once. I’ll share the basic steps, common issues, and how to keep everything running smoothly. My goal is to give you a simple guide on how to make and run such a system.

System Requirements

Functional Requirements:

  • User Management: Includes registration, login, and profile management.
  • Tweeting: Enables users to broadcast short messages.
  • Retweeting: This lets users share others’ content.
  • Timeline: Showcases tweets from the user and those they follow.

Non-functional Requirements:

  • Scalability: Must accommodate millions of users.
  • Availability: High uptime is the goal, achieved through multi-regional deployments.
  • Latency: Prioritizes real-time data retrieval and instantaneous content updates.
  • Security: Ensures protection against unauthorized breaches and data attacks.

Architecture Overview

This diagram outlines a microservices-based social media platform design. The user’s request flows through a CDN, then a load balancer to distribute the load among web servers. Core services and data storage solutions like DynamoDB, Blob Storage, and Amazon RDS are defined. An intermediary cache ensures fast data retrieval, and the Amazon Elasticsearch Service provides advanced search capabilities. Asynchronous tasks are managed through SQS, and specialized services for trending topics, direct messaging, and DDoS mitigation are included for a holistic approach to user experience and security.

Scalability

  • Load Balancer: Directs traffic to multiple servers to balance the load.
  • Microservices: Functional divisions ensure scalability without interference.
  • Auto Scaling: Adjusts resources based on the current demand.

High Availability

  • Multi-Region Deployment: Geographic redundancy ensures uptime.
  • Data Replication: Databases like DynamoDB replicate data across different locations.
  • CDN: Content Delivery Networks ensure swift asset delivery, minimizing latency.

Security

  • Authentication: OAuth 2.0 for stringent user validation.
  • Authorization: Role-Based Access Control (RBAC) defines user permissions.
  • Encryption: SSL/TLS for data during transit; AWS KMS for data at rest.
  • DDoS Protection: AWS Shield protects against volumetric attacks.

Data Design (NoSQL, e.g., DynamoDB)

User Table

Tweets Table

Timeline Table

Multimedia Content Storage (Blob Storage)

In the multimedia age, platforms akin to Twitter necessitate a system adept at managing images, GIFs, and videos. Blob storage, tailored for unstructured data, is ideal for efficiently storing and retrieving multimedia content, ensuring scalable, secure, and prompt access.

Backup Databases

In the dynamic world of microblogging, maintaining data integrity is imperative. Backup databases offer redundant data copies, shielding against losses from hardware mishaps, software anomalies, or malicious intents. Strategically positioned backup databases bolster quick recovery, promoting high availability.

Queue Service

The real-time interaction essence of platforms like Twitter underscores the importance of the Queue Service. This service is indispensable when managing asynchronous tasks and coping with sudden traffic influxes, especially with high-profile tweets. This queuing system:

  • Handles requests in an orderly fashion, preventing server inundations.
  • Decouples system components, safeguarding against cascading failures.
  • Preserves system responsiveness during high-traffic episodes.

Workflow Design

Standard Workflow

  • Tweeting: User submits a tweet → Handled by the Tweet Microservice → Authentication & Authorization → Stored in the database → Updated on the user’s timeline and followers’ timelines.
  • Retweeting: User shares another’s tweet → Retweet Microservice handles the action → Authentication & Authorization → The retweet is stored and updated on timelines.
  • Timeline Management: A user’s timeline combines tweets, retweets, and tweets from users they follow. Caching mechanisms like Redis can enhance timeline retrieval speed for frequently accessed ones.

Enhanced Workflow Design

Tweeting by High-Profile Users (high retrieval rate):

  • Tweet Submission: Elon Musk (or any high-profile user) submits a tweet.
  • Tweet Microservice Handling: The tweet is directed to the Tweet Microservice via the Load Balancer. Authentication and Authorization checks are executed.
  • Database Update: Once approved, the tweet is stored in the Tweets Table.
  • Deferred Update for Followers: High-profile tweets can be efficiently disseminated without overloading the system using a publish/subscribe (Pub/Sub) mechanism.
  • Caching: Popular tweets, due to their high retrieval rate, benefit from caching mechanisms and CDN deployments.
  • Notifications: A selective notification system prioritizes active or frequent interaction followers for immediate notifications.
  • Monitoring and Auto-scaling: Resources are adjusted based on real-time monitoring to handle activity surges post high-profile tweets.

Advanced Features and Considerations

Though the bedrock components of a Twitter-esque system are pivotal, integrating advanced features can significantly boost user experience and overall performance.

Trending Topics and Analytics

A hallmark of platforms like Twitter is real-time trend spotting. An ever-watchful service can analyze tweets for patterns, hashtags, or mentions, displaying live trends. Combined with analytics, this offers insights into user patterns and preferences, peak tweeting times, and favoured content.

Direct Messaging

Given the inherently public nature of tweets, a direct messaging system serves as a private communication channel. This feature necessitates additional storage, retrieval mechanisms, and advanced encryption measures to preserve the sanctity of private interactions.

Push Notifications

To foster user engagement, real-time push notifications can be implemented. These alerts can inform users about new tweets, direct messages, mentions, or other salient account activities, ensuring the user stays connected and engaged.

Search Functionality

With the exponential growth in tweets and users, a sophisticated search mechanism becomes indispensable. An advanced search service, backed by technologies like ElasticSearch, can render the task of content discovery effortless and precise.

Monetization Strategies

Integrating monetisation mechanisms is paramount to ensure the platform’s sustainability and profitability. This includes display advertisements, promoted tweets, business collaborations, and more. However, striking a balance is crucial, ensuring these monetization strategies don’t intrude on the user experience.

To make a site like Twitter, you need a good system, strong safety, and features people like. Basic things like balancing traffic, organizing data, and keeping it safe are a must. But what really makes a site stand out are the new and advanced features. By thinking carefully about all these things, you can build a site that’s big and safe, but also fun and easy for people to use.

If you enjoyed reading this and would like to explore similar content, please refer to the following link:

System Design 101: Adapting & Evolving Design Patterns in Software Development

Enterprise Software Development 101: Navigating the Basics

Designing an AWS-Based Notification System

System Design Interview: Serverless Web Crawler using AWS

AWS-Based URL Shortener: Design, Logic, and Scalability

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Preparing for a System Design Interview: Focus on Trade-offs, Not Mechanics

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Are you getting ready for a system design interview? It is critical to approach it with the proper mindset and preparation. System design deals with components at a higher level, so staying out of the trenches is vital. Instead, interviewers are looking for a high-level understanding of the system, the ability to identify key components and their interactions, and the ability to weigh trade-offs between various design options.

During the interview, pay attention to the trade-offs rather than the mechanics. You must make decisions about the system’s scalability, dependability, security, and cost-effectiveness. Understanding the trade-offs between these various aspects is critical to make informed decisions.

Here are a few examples to prove my point:

  • If you’re creating a social media platform, you must choose between scalability and cost-effectiveness. Should you, for example, use a scalable but expensive cloud platform or a less expensive but less scalable hosting service?
  • When creating an e-commerce website, you must make trade-offs between security and usability. Should you, for example, require customers to create an account with a complex password or let them checkout as a guest with a simpler password?
  • When designing a transportation management system, you must balance dependability and cost-effectiveness. Should you, for example, use real-time data to optimise routes and minimise delays, or should you rely on historical data to save money?