How NETFLIX Delivers Flawless Streaming: An Insider's View of Architecture
When we dive into the world of Netflix, it seems like magic: our favorite shows and movies start playing without any lag, the picture quality is always great, and the recommendations never cease to amaze us with their precise hit on our interests. But what lies behind this seamless experience? How does Netflix deliver flawless streaming quality to millions of users around the world? The answer lies in the sophisticated and complex architecture of the system that stands behind it all.
Netflix is a symbol of entertainment, unlimited viewing, and cutting-edge streaming services. Netflix’s rapid rise to fame can be attributed not only to its vast content library and global presence, but also to its sustainable and innovative architecture.
From its inception in 1997 as a DVD rental service to becoming the world's largest streaming company, Netflix has continually used cutting-edge technology to change the way we consume media.
Netflix's architecture is designed to efficiently and reliably deliver content to millions of users simultaneously. The scalability of Netflix's infrastructure is critical given its more than 200 million members worldwide.
Let's dive into the details of Netflix's architecture and uncover how it continues to shape our experience watching our favorite shows and movies.
Why is it important to understand Netflix System Architecture?
Understanding the Netflix System Architecture is important for several reasons. First and foremost, it helps you understand how Netflix serves millions of customers around the world, delivering a seamless streaming experience. Learning the nuances of this architecture allows you to better understand the technologies and methods behind its success.
Moreover, other industries can benefit from using Netflix’s architecture as a model for designing scalable, reliable, and efficient systems. Its design principles and best practices can teach us important lessons about building and optimizing complex distributed systems.
Understanding Netflix's architecture also gives us a glimpse into the constant innovation that drives the evolution of digital media.
Understanding System Design Requirements
System design is key when developing complex software or technology infrastructure. These specifications serve as the foundation around which the entire system is built, defining its characteristics and shaping the final product. But what are the requirements for system design and why are they so important? Let's find out.
Functional requirements
The functional requirements of a system define the functions and capabilities it must include. These specifications describe the main purpose of the system and detail how the various components or modules interact. For example, the functional requirements for a streaming platform like Netflix might include:
Create an account: Users should be able to easily create accounts by providing the necessary registration details.
Login: Registered users should be able to securely log into their accounts using their credentials.
Content recommendations: The platform should offer personalized content recommendations based on user preferences, browsing history, and other data.
Video playback capabilities: Users should be able to seamlessly stream videos with playback control features such as play, pause, rewind, and fast forward.
Non-functional requirements
Non-functional requirements define the behavior of the system in various scenarios and ensure that certain quality standards are met. They cover aspects of performance, scalability, reliability, security, and compliance. For example, non-functional requirements for a streaming platform like Netflix might include:
Performance requirements: The system must maintain low latency and high throughput during times of high load.
Compliance requirements: The platform must comply with user data protection standards.
Scalability requirements: The infrastructure must be scalable to handle growing user traffic without losing performance.
Safety requirements: It is necessary to implement reliable authentication and encryption procedures to prevent unauthorized access to user information.
Requirements for reliability and availability: The system must include fault-tolerance methods and provide a high level of availability.
Transition to cloud technologies
After a major database corruption outage in August 2008, Netflix came to a major realization: it needed to move away from single points of failure to highly reliable, horizontally scalable cloud solutions. Netflix began the revolutionary journey by choosing Amazon Web Services (AWS) as its cloud provider and moving the majority of its services to the cloud by 2015. After seven years of intensive work, the cloud migration was completed in early January 2016, marking the closure of the streaming service’s last remaining data center.
However, the transition to the cloud was not easy. Netflix adopted a cloud strategy by completely redesigning its operating model and technology stack. This required the implementation of NoSQL databases, denormalization of the data model, and the transition from a monolithic application to hundreds of microservices. It also required cultural changes such as the adoption of DevOps procedures, continuous delivery, and the creation of a self-service environment for engineers. Despite the challenges, this transition has made Netflix a cloud-native business that is well-positioned for future expansion and innovation in the rapidly changing world of online entertainment.
Netflix's Architectural Triumvirate
A strong architectural triumvirate—Client, Backend, and Content Delivery Network (CDN)—is responsible for Netflix’s seamless user experience. With millions of viewers worldwide, each component is critical to delivering content.
Client
The client-side architecture is at the heart of the Netflix user experience. This includes the wide range of devices that users use to access Netflix, such as computers, smart TVs, and smartphones. Netflix uses a combination of web interfaces and native apps to provide a consistent user experience across platforms. Regardless of the device, these clients manage playback controls, user interactions, and interface display to provide a unified experience. Users can easily browse the vast content library and enjoy uninterrupted streaming thanks to the streamlined client-side architecture.
Backend
The backend architecture is the foundation of all behind-the-scenes operations at Netflix. User accounts, content catalogs, recommendation algorithms, billing systems, and other systems are managed by a complex network of servers, databases, and microservices. In addition to processing user data and coordinating content delivery, the backend optimizes content delivery and personalizes recommendations using advanced technologies like big data analytics and machine learning, improving user satisfaction and engagement.
Netflix’s backend architecture has evolved significantly over time. In 2007, it moved to a cloud-native infrastructure, and in 2018, it adopted Spring Boot as its primary Java framework. Combined with the scalability and reliability provided by AWS (Amazon Web Services), proprietary technologies such as Ribbon, Eureka, and Hystrix have played a key role in effectively coordinating backend operations.
Content Delivery Network (CDN)
The Content Delivery Network completes the Netflix architectural triangle. The Content Delivery Network (CDN) is a strategically located global network of servers that aims to deliver content to users with optimal reliability and minimal latency. Netflix operates its own Content Delivery Network (CDN), called Open Connect.
It reduces buffering and ensures smooth playback by caching and serving content from nodes closest to the user. Even during periods of high demand, Netflix reduces network congestion and maximizes bandwidth usage by distributing content across multiple servers around the world. This decentralized approach to content delivery improves the viewing experience for global viewers while reducing buffering times and improving streaming quality.
Client-side components
Web interface
Netflix's web interface has undergone significant changes in recent years, moving from Silverlight to HTML5 for streaming premium video content. This transition has resulted in improved responsiveness, compatibility, and support for modern web technology standards. HTML5 provides support for high-quality video, interactivity, and an improved user experience, offering a smooth and reliable viewing experience.
Mobile and TV applications
Netflix's mobile and TV apps are also constantly evolving to meet the needs of different platforms and devices. While mobile apps allow users to watch content on the go, TV apps provide the ability to watch on the big screen. Each app is tailored to the device's features to offer the most convenient and optimized experience.
CDN and Caching
Netflix's infrastructure relies on its content delivery network (CDN), also known as Netflix Open Connect, which allows it to easily deliver content to millions of viewers around the world. A globally distributed CDN is key to ensuring that customers in different locations receive high-quality content.
Netflix Open Connect CDN works by placing servers, called Open Connect Appliances (OCAs), strategically close to Internet service providers (ISPs) and their users. When content delivery peaks, this proximity reduces latency and ensures efficient operation. Netflix maximizes bandwidth utilization and reduces reliance on expensive backbone bandwidth by pre-hosting content on ISP networks, improving the overall streaming experience.
Scalability is one of the key features of the Netflix CDN. With OCAs installed in nearly 1,000 locations around the world, including remote locations like islands and the Amazon, Netflix is able to handle the growing demand for streaming services across geographies.
Additionally, Netflix provides OCAs to qualified ISPs so that they can offer Netflix content directly from their networks. This strategy provides an improved streaming experience for subscribers and reduces ISP operating costs. Netflix creates mutually beneficial relationships with ISPs by offering localized content distribution and partnering with them, which improves the overall streaming ecosystem.
Transforming Video Processing: The Microservices Revolution at Netflix
By implementing microservices, Netflix fundamentally transformed its video processing system, providing unmatched scalability and flexibility to meet the needs of both studio operations and user streaming. The transition to a microservices-based platform from a monolithic platform ushered in a new era of agility and speed of feature development.
Each step of the video workflow is represented by a separate microservice, allowing for simplified orchestration and decoupling of functionality. From video review to complexity analysis and encoding, these services work together to create great video assets that are suitable for both studio and streaming use cases. Microservices have delivered tangible results, enabling rapid iteration and adaptation to changing business requirements.
Playback process in Netflix Open Connect
Users around the world can enjoy a seamless and excellent viewing experience thanks to the Netflix Open Connect playback process. It works as follows:
Status reports: Open Connect Appliances (OCAs) regularly report their routes, content availability, and overall health to the cache management services in Amazon Web Services (AWS).
User request: A user on a client device requests to play a TV show or movie through the Netflix application hosted in AWS.
Authorization and file selection: After verifying user authorization and licenses, AWS Replay Services selects the exact files needed to process the replay request.
Routing service: The AWS Routing Service selects which OCAs to serve files from based on data stored by the Cache Management Service. These OCAs are passed to the playback services to generate their URLs.
Content delivery: Playback services send the URLs of the corresponding OCAs to the client device. When the requested files are transferred to the client device via HTTP/HTTPS, the selected OCA starts serving them.
Playback process in Netflix Open Connect
Users around the world can enjoy a seamless and excellent viewing experience thanks to the Netflix Open Connect playback process. It works as follows:
Status reports: Open Connect Appliances (OCAs) regularly report their routes, content availability, and overall health to the cache management services in Amazon Web Services (AWS).
User request: A user on a client device requests to play a TV show or movie through the Netflix application hosted in AWS.
Authorization and file selection: After verifying user authorization and licenses, AWS Replay Services selects the exact files needed to process the replay request.
Routing service: The AWS Routing Service selects which OCAs to serve files from based on data stored by the Cache Management Service. These OCAs are passed to the playback services to generate their URLs.
Content delivery: Playback services send the URLs of the corresponding OCAs to the client device. When the requested files are transferred to the client device via HTTP/HTTPS, the selected OCA starts serving them.
Databases in Netflix Architecture
Using Amazon S3 for Seamless Media Storage
Netflix's ability to survive the AWS outage on April 21, 2022, demonstrated the value of its cloud infrastructure, particularly its reliance on Amazon S3 for data storage. Netflix's systems were built to withstand such outages, using services like SimpleDB, S3, and Cassandra.
Netflix's infrastructure is built on Amazon S3 (Simple Storage Service) for media storage, which supports the streaming giant's massive collection of movies, TV shows, and original content. Petabytes of data are needed to serve millions of Netflix users around the world, and S3 is the ideal choice for storing this data due to its scalability, reliability, and high availability.
Another important factor that made Netflix choose S3 for media storage is scalability. With S3, Netflix can easily expand its storage capacity without having to worry about adding additional hardware or maintaining a complex storage infrastructure as its content collection grows. To meet the growing demand for streaming content without losing user experience or speed, Netflix needs to be scalable.
Adopting NoSQL for Scalability and Flexibility
The need for structured data access within a highly distributed infrastructure drives the database selection process at Netflix. Netflix adopted the NoSQL distributed database paradigm after realizing the limitations of traditional relational models in the context of Internet-scale operations. Three key NoSQL solutions stand out in their database ecosystem: Cassandra, Hadoop/HBase, and SimpleDB.
Amazon SimpleDB
When Netflix moved to the AWS cloud, Amazon’s SimpleDB became an obvious choice for many use cases. It was attractive due to its powerful query capabilities, automatic replication across availability zones, and durability. SimpleDB’s hosting solution reduced operational costs, which is consistent with Netflix’s policy of using cloud providers for undifferentiated operations.
Apache HBase
Apache HBase has evolved as a practical, high-performance solution for Hadoop-based systems. Its dynamic load-sharing strategy simplifies load balancing and clustering, which is critical to handling Netflix’s growing data volume. HBase’s massive consistency is enhanced by support for distributed counters, range queries, and data compression, making it suitable for a variety of use cases.
Apache Cassandra
The open source NoSQL Cassandra database delivers performance, scalability, and flexibility. Its dynamic cluster expansion and horizontal scalability meet Netflix's requirements for unlimited scale. With its adaptive consistency, replication mechanisms, and flexible data model, Cassandra is ideal for cross-region deployments and scaling without single points of failure.
Because each NoSQL utility is best suited for a specific set of use cases, Netflix has adopted several of them. While Cassandra excels at cross-region deployments and fault-tolerant scaling, HBase integrates naturally with the Hadoop platform. Adopting NoSQL requires a learning curve and operational costs, but the benefits in scalability, availability, and performance make the investment worthwhile.
MySQL in Netflix's Billing Infrastructure
Netflix's billing system has undergone a significant transformation as part of a broader migration to AWS's cloud architecture. Because Netflix relies heavily on its billing system to operate, the move to AWS was done with great care to minimize the impact on user experience and ensure compliance with strict financial standards.
Tracking billing periods, monitoring payment statuses, and providing data for financial reporting systems are just some of the tasks performed by Netflix's billing infrastructure. The billing engineering team managed a complex ecosystem that included batch jobs, APIs, connectors to other services, and data management to perform these functions.
The choice of database technology was one of the most important decisions made during the migration process. MySQL was chosen as the database solution due to the need for scalability and the ACID transaction requirements for payment processing.
Building robust tools, optimizing code, and removing unnecessary data were integral parts of the migration process to adapt to the new cloud architecture. Before migrating current user data, a thorough testing process was conducted using clean data sets and proxy servers to handle traffic redirection.
Migrating to MySQL on AWS was a complex process that required careful planning, methodical implementation, and constant testing and iteration. Despite the challenges, the transition was a success, allowing Netflix to leverage the scalability and reliability of AWS cloud services for its billing system.
Content Processing Process in Netflix Architecture
Netflix's content workflow is a systematic approach to managing digital assets provided by content and fulfillment partners. Key phases of this process include ingest, transcoding, and packaging.
Ingestion
During the ingest stage, source files such as audio, timed text, or video are subjected to rigorous testing for accuracy and compliance. This testing includes semantic signal analysis, file format verification, decodability of compressed bitstreams, compliance with Netflix delivery criteria, and data integrity.
Transcoding and Packaging
Once the ingest stage has been successfully completed, the source files are transcoded to create output elementary streams. These streams are then encrypted and placed into containers ready for distribution and streaming.
Delivering Seamless Streaming with Netflix's Canary Model
Because client applications are the primary way users interact with a brand, they must be of high quality for global digital products. Netflix’s system architecture invests heavily in rigorous evaluation of app updates. However, with Netflix available on thousands of devices and supported by hundreds of independent microservices, conducting thorough internal testing is challenging. As such, it is critical to support release decisions with solid data from the update process.
To speed up the evaluation of updated client applications, Netflix created a dedicated team to collect real-world health data. This investment in the system has resulted in faster development speeds, improved application quality, and improved development processes.
Client Apps: Netflix uses two methods to update its client apps: direct downloads and app store submissions. Direct downloads increase control over distribution.
Deployment Strategies: While the benefits of regular and staged releases for client applications are well known, software updates come with their own challenges. Since each user device streams data, efficient signal sampling is critical. Netflix’s deployment strategies are tailored to address the unique challenges of diverse user devices and complex microservices. The approach varies by client type — for example, smart TVs versus mobile apps. New versions of client applications are gradually made available through staged rollouts, allowing for rapid failure handling and smart scaling of backend services. During deployment, control over client-side error rates and upgrade acceptance rates ensures consistency and efficiency of the deployment process.
Phased deployments: To reduce risks and scaling server services intelligently, staged rollouts involve the gradual deployment of new versions of software.
AB tests/client canaries: Netflix uses an intensive version of A/B testing known as “Client Canaries,” which involves testing full apps to ensure timely updates within hours.
Orchestration Reduces the burden of frequent deployments and analysis. It is useful for managing A/B tests and client canaries.
Ultimately, Netflix's client canaries model ensures frequent app updates.
Netflix Architecture Diagram
Netflix’s system architecture is a complex ecosystem consisting of Python and Java using Spring Boot for backend services, and Apache Kafka and Flink for data processing and real-time streaming. On the frontend, Redux, React.js, and HTML5 are used to create an engaging user experience. Multiple databases, including Cassandra, HBase, SimpleDB, MySQL, and Amazon S3, provide real-time analytics and processing of massive amounts of media content. Jenkins and Spinnaker help with continuous integration and deployment, and AWS supports the entire infrastructure with scalability, reliability, and global reach.
Netflix's commitment to delivering a seamless entertainment experience to its massive international audience is demonstrated by the fact that these technologies make up only a small part of their vast tech stack.
Conclusion
Netflix's system architecture has revolutionized the entertainment industry, from a DVD rental service to a major global player in streaming.
Netflix's architecture, powered by Amazon Web Services (AWS), delivers seamless streaming to a global audience. Netflix ensures seamless content delivery across devices through its client, server, and content delivery network (CDN) architecture.
The innovative use of HTML5 and personalized recommendations offered by Netflix's system architecture greatly enhance the user experience.
Despite some challenges the company faced, the move to the cloud was an important step in strengthening Netflix’s position. In the rapidly evolving world of online entertainment, Netflix has prepared itself for future growth and innovation by adopting microservices, NoSQL databases, and cloud solutions. Understanding Netflix’s system can be useful for any tech company.
In simple terms, Netflix’s system architecture is designed to change the way we consume media content—it’s not just about the technology. Behind the scenes, this architecture ensures a seamless viewing experience, enhancing the entertainment experience for every viewer.
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