Archive for December 2022

Every popular software should have a Rate Limiter. It prevents DDOS attack, reduces cost and prevents servers from being overloaded.

There are some tricky questions to be considered during implementation of Rate Limiter:

• Where to put Rate Limiter: client-side, server-side, gateway?
• Algorithms for rate limiting. There are many algorithms with pros and cons: Token bucket, Leaking bucket, Fixed window counter, Sliding window log, Sliding window counter. Your business needs will define the right algorithm.
• How are rate limiting rules created?
• Where are the rules stored?
• How to handle requests that are rate limited?

These questions are disclosed in a very interesting Chapter 4 of the book:

Four standard steps for system design interview. However, I would think about them wider: as about four initial steps to design the software.

• Step 1. Understand the problem and establish design scope
• Step 2. Propose high-level design and get buy-in
• Step 3. Design deep dive
• Step 4. Wrap up

The chapter 3 of the book discovers details about each step, good questions to ask (to think about), DO’s and DONT’s. It also shows good example of the process of designing a news feed system.