Designing a Scalable Messaging Application: A System Design Mock Interview

🧩The main use case of the messaging application is sending and receiving messages, while group messaging functionality can be left out for the interview purposes.

⚖️The system needs to handle high traffic, with a target of 10 billion messages sent per day and the ability to double that within a year.

⚙️The system can be designed with APIs as the entry point, using RESTful architecture for sending and receiving messages.

🔁Eventual consistency can be acceptable for message delivery, allowing for some delay between sending and receiving messages.

🌐Load balancing is crucial for handling high traffic, ensuring even distribution of requests among multiple API servers.

What are the functional requirements of the messaging application?

—The functional requirements include the ability to send and receive messages, with an eventual consistency model for message delivery.

How should the system handle high traffic?

—The system should incorporate load balancing to distribute requests among multiple API servers, allowing for horizontal scaling.

What factors should be considered when choosing a database for the application?

—The decision of a SQL or NoSQL database should be based on the complexity of data relationships and the need for scalability.

What is the recommended latency for message processing?

—The aim is to achieve low latency, with the majority of requests completing within a few hundred milliseconds.

What is the expected data storage requirement for the messaging application?

—Based on the estimated traffic, the system should be able to handle terabytes or petabytes of data over time.

01:13Mark, a former engineering manager at Google, designs a scalable messaging application with APIs for sending and receiving messages.

02:30The main use case of the messaging application is sending and receiving messages, while group messaging functionality can be left out for the interview purposes.

04:07The system needs to handle high traffic, with a target of 10 billion messages sent per day and the ability to double that within a year.

06:19The system can be designed with APIs as the entry point, using RESTful architecture for sending and receiving messages.

11:40Eventual consistency can be acceptable for message delivery, allowing for some delay between sending and receiving messages.

15:30Load balancing is crucial for handling high traffic, ensuring even distribution of requests among multiple API servers.

21:00The decision of a SQL or NoSQL database should be based on the complexity of data relationships and the need for scalability.

22:00The aim is to achieve low latency, with the majority of requests completing within a few hundred milliseconds.