Section 01
Pub/Sub & Event-Driven Systems
0 / 4
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One Order, Five Consumers
Easy
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The Slow Subscriber
Medium
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Too Many Event Types
Medium
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Event-Driven Workflow Challenge
Hard
Section 02
Idempotency, Ordering & Delivery Guarantees
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The Payment Ran Twice
Easy
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Cancelled Before Created
Medium
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Exactly Once Requirement
Hard
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Commit Succeeded, Publish Failed
Hard
Section 03
APIs & Service Communication
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The Chatty Mobile App
Easy
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Internal Calls Waste Capacity
Medium
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The Public API Needs Protection
Medium
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Version Without Breaking Clients
Medium