Watch prices on 500 million products with a polite crawler and a million browsers, verify what you are told, and notify subscribers within minutes of a drop.
Backend and product engineers designing software behavior.
Your approach: Use diagrams, tables or prose for customer contracts, state transitions and data ownership; include APIs only to the depth the question requests.
Design a Price Tracking Service. Watch prices on 500 million products with a polite crawler and a million browsers, verify what you are told, and notify subscribers within minutes of a drop. 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 a Price Tracking Service. 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: Notification channels? Retailers?
Identify users, required behavior and exclusions. Answer: How many products, how many users? Where can prices come from?
Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: How fresh must a notification be? How much can we trust an extension user?
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 a Price Tracking Service. 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: Latency for charts? Consistency? Notification channels? Retailers?
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.