System Design
  • Introduction
  • Glossary of System Design
    • System Design Basics
    • Key Characteristics of Distributed Systems
    • Scalability - Harvard lecture
      • Scalability for Dummies - Part 1: Clones
      • Scalability for Dummies - Part 2: Database
      • Scalability for Dummies - Part 3: Cache
      • Scalability for Dummies - Part 4: Asynchronism
    • Trade-off
      • CAP Theorem
      • Performance vs scalability
      • Latency vs throughput
      • Availability vs consistency
    • Load Balancing
      • Load balancer
    • Proxies
      • Reverse proxy
    • Cache
      • Caching
    • Asynchronism
    • Processing guarantee in Kafka
    • Database
      • Relational database management system (RDBMS)
      • Redundancy and Replication
      • Data Partitioning
      • Indexes
      • NoSQL
      • SQL vs. NoSQL
      • Consistent Hashing
    • Application layer
    • DNS
    • CDN
    • Communication
      • Long-Polling vs WebSockets vs Server-Sent Events
    • Security
    • Lambda Architecture
  • OOD design
    • Concepts
      • Object-Oriented Basics
      • OO Analysis and Design
      • What is UML?
      • Use Case Diagrams
    • Design a parking lot
  • System Design Cases
    • Overview
    • Design a system that scales to millions of users on AWS
    • Designing a URL Shortening service like TinyURL
      • Design Unique ID Generator
      • Designing Pastebin
      • Design Pastebin.com (or Bit.ly)
    • Design notification system (scott)
      • Designing notification service
    • Designing Chat System
      • Designing Slack
      • Designing Facebook Messenger
    • Design Top K System
    • Designing Instagram
    • Design a newsfeed system
      • Designing Facebook’s Newsfeed
      • Design the data structures for a social network
    • Designing Twitter
      • Design the Twitter timeline and search
      • Designing Twitter Search
    • Design Youtube - Scott
      • Design live commenting
      • Designing Youtube or Netflix
    • Designing a Web Crawler
      • Designing a distributed job scheduler
      • Designing a Web Crawler/Archive (scott)
      • Design a web crawler
    • Designing Dropbox
    • Design Google Doc
    • Design Metrics Aggregation System
      • Design Ads Logging System
    • Design Instacart
    • Design a payment system
      • Airbnb - Avoiding Double Payments in a Distributed Payments System
    • Design Distributed Message Queue
      • Cherami: Uber Engineering’s Durable and Scalable Task Queue in Go
    • Design Distributed Cache
      • Design a key-value cache to save the results of the most recent web server queries
    • Design a scalable file distribution system
    • Design Amazon's sales ranking by category feature
    • Design Mint.com
    • Design Autocomplete System
      • Designing Typeahead Suggestion
    • Designing an API Rate Limiter
      • Designing Rate Limiter
    • Design Google Map
      • Designing Yelp or Nearby Friends
      • Designing Uber backend
    • Designing Ticketmaster
      • Design 12306 - Scott
    • Design AirBnB or a Hotel Booking System
  • Paper Reading
    • MapReduce
  • Other Questions
    • What happened after you input the url in the browser?
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  • Concept
  • Principles

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  1. OOD design
  2. Concepts

Object-Oriented Basics

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Last updated 5 years ago

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Concept

  • Objects: Objects represent a real-world entity and the basic building block of OOP. For example, an Online Shopping System will have objects such as shopping cart, customer, product item, etc.

  • Class: Class is the prototype or blueprint of an object. It is a template definition of the attributes and methods of an object. For example, in the Online Shopping System, the Customer object will have attributes like shipping address, credit card, etc., and methods for placing an order, canceling an order, etc.

Principles

  • Encapsulation: Encapsulation is the mechanism of binding the data together and hiding it from the outside world. Encapsulation is achieved when each object keeps its state private so that other objects don’t have direct access to its state. Instead, they can access this state only through a set of public functions.

  • Abstraction: Abstraction can be thought of as the natural extension of encapsulation. It means hiding all but the relevant data about an object in order to reduce the complexity of the system. In a large system, objects talk to each other, which makes it difficult to maintain a large code base; abstraction helps by hiding internal implementation details of objects and only revealing operations that are relevant to other objects.

  • Inheritance: Inheritance is the mechanism of creating new classes from existing ones.

  • Polymorphism: Polymorphism (from Greek, meaning “many forms”) is the ability of an object to take different forms and thus, depending upon the context, to respond to the same message in different ways. Take the example of a chess game; a chess piece can take many forms, like bishop, castle, or knight and all these pieces will respond differently to the ‘move’ message.