Functional & Non-Functional Requirements

Requirements

To design a video sharing platform similar to YouTube or Netflix, we must first categorize the functional and non-functional requirements. Functional requirements include user authentication, video upload, streaming, and search capabilities. Additionally, the platform should allow users to like, comment, and subscribe to channels. Non-functional requirements encompass scalability, availability, performance, and data security.

Scalability is crucial as we anticipate rapid growth in both users and content. The platform should efficiently handle spikes in traffic, especially during peak viewing hours, ensuring smooth streaming experiences. Additionally, the system should be designed to provide low latency video playback with a high-quality viewing experience across different devices.

Capacity Estimation

Estimation

To estimate the system design, we first need to define the scale of operations. If we aim to accommodate a million active users with a conservative estimate of 10 videos uploaded per minute, our storage needs will exceed several terabytes. Furthermore, live streaming capabilities may require additional bandwidth and processing power.

Considering the infrastructure, we will need multiple services, including video processing, storage, user authentication, and search service. Based on comparable systems, we can estimate that building out the backend will take a team of 4-5 engineers an estimated 6-8 months to reach a minimum viable product (MVP), alongside ongoing maintenance and feature development thereafter.

API Design

API

The API for the platform will provide endpoints for various functionalities such as user management, video uploads, and search capabilities. For instance, here’s a list of essential endpoints:

• POST /api/users/register - for user registration
• POST /api/users/login - for user authentication
• POST /api/videos/upload - for uploading videos
• GET /api/videos/{id} - to get video details
• GET /api/videos/search - to search for videos

These endpoints will support JSON format for request and response bodies, ensuring easy interaction with the front end.

Database Design

Database

For the database schema, we will employ a relational database such as PostgreSQL for structured data and NoSQL like MongoDB for unstructured metadata. Key entities in the relational database will include Users, Videos, Comments, and Subscriptions.

A NoSQL database will hold video metadata, such as the duration, tags, thumbnails, and streaming URLs. The architecture would ensure efficient query handling and relationships between tables while supporting high availability.

High Level Design

High-Level Architecture

The high-level architecture consists of several major components. The client application (web and mobile) will interact with a load balancer, which divides incoming requests to multiple backend services. Essential services include the user service, video service, search service, and comments service.

Furthermore, below these services, we will utilize a database layer that includes both our relational and NoSQL databases. Caching solutions like Redis will help speed up frequent queries, while a message queue like RabbitMQ can handle asynchronous tasks such as video processing and notifications.

Request Flows

Request Flow

The request flow begins when a user seeks to upload a video. The client sends a request to the load balancer, which then directs it to the video processing service. This service validates and stores the video in temporary storage before encoding it into various formats for streaming.

Once the video is ready, metadata is stored to the database, and the user is notified about the upload status. For fetching a video, the request goes from the client to the load balancer and then to the video service, which retrieves the video using the ID and streams it back to the user.

Detailed Component Design

Components

The core components of the platform include:

• User Service: Manages user registration, authentication, and user profiles.
• Video Service: Handles video upload, processing, retrieval, and streaming.
• Search Service: Enables video discovery through tags, titles, and descriptions.
• Comments Service: Manages comments and likes associated with videos.
• Notification Service: Sends notifications for new subscriptions or updates.

The interaction between these components ensures cohesive system functionality and provides a seamless user experience.

Trade-offs & Tech Choices

Trade-Offs

When designing the system, there are trade-offs to consider like using different databases. A relational database offers ACID compliance, while a NoSQL database allows for flexibility and scalability. Evaluating the specific needs of the platform is essential, as it may require balancing data integrity with performance.

Additionally, while prioritizing low latency for streaming, there could be a compromise on the speed of video uploads due to processing time. This requires optimizing video compression and encoding to mitigate delays.

Failure Scenarios & Bottlenecks

Failure Scenarios

Possible failure scenarios include server outages, database failures, or issues in video processing. To tackle these, introducing redundancy and failover strategies is crucial. For example, employing a multi-region deployment can ensure that if one server fails, another can take over seamlessly.

Moreover, implementing monitoring tools that alert relevant teams about service disruptions will expedite recovery efforts and maintain an optimal user experience, keeping user satisfaction high even during unexpected scenarios.

Future Improvements

Future Improvements

Future enhancements might include incorporating advanced recommendation algorithms to suggest targeted content based on user preferences or behavior. Leveraging machine learning can significantly enhance user experience by providing personalized feeds.

Moreover, integrating community features like live streaming, user-generated playlists, or collaborative features may enrich the platform’s appeal and engagement level. Over time, continual feedback collection will guide iterative improvements to meet evolving user needs.

High Level Architecture Diagram

Database ER Diagram

Request Flow Sequence Diagram