Every goal on 25 million open apps within two seconds: SSE or WebSockets, pub/sub to the right server, resume by seq, hot topics, reconnect storms and push.
Infrastructure, platform and reliability engineers.
Your approach: Use diagrams or prose to explain responsibilities, state, capacity and failure behavior. Show the calculations requested by the question.
Design Real-Time Updates for Millions of Clients. Every goal on 25 million open apps within two seconds: SSE or WebSockets, pub/sub to the right server, resume by seq, hot topics, reconnect storms and push. Work from the scoping questions below. State assumptions for any unspecified load, guarantee or target, then trace your design end to end. Explain one difficult case and a credible alternative; the worked example is a reference, not a required implementation.
Resolve the scoping questions for Real-Time Updates for Millions of Clients. Separate stated behavior from assumptions, and identify what is outside your design.
Declare relevant volume, latency, freshness, quality or cost targets with units. Show calculations or an evaluation plan that can test them; unspecified targets are your assumptions, not hidden pass criteria.
Explain how your guarantees hold in a difficult case relevant to this subject. Address: One region? What changes every second?
Identify users, required behavior and exclusions. Answer: How many clients, and how skewed? How fresh?
Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: What does the app send? Can a fan miss an update?
Estimate the dominant workload and resource demand with units and explicit assumptions. For a learned system, also state how quality is measured and what data is available.
Draw or describe the responsibilities needed for Real-Time Updates for Millions of Clients. Trace a representative request, event or job from its input to a visible result; identify durable state owners.
Walk through a difficult case step by step, including detection and recovery. Consider: With the app closed? One region? What changes every second?
Compare a credible alternative using your chosen workload and guarantees. Explain a remaining risk, a signal to watch and when you would change the design.