Start by clarifying requirements and scope, then focus on the core challenge of real-time collaborative editing. Propose a high-level architecture that separates concerns: document storage, real-time synchronization, and conflict resolution. Dive deep into the chosen conflict resolution algorithm (e.g., OT or CRDT) and discuss trade-offs.
Pro tip: Emphasize the importance of operational transformation (OT) or CRDTs for conflict resolution, and discuss how to handle offline editing and synchronization. Show awareness of scalability challenges like fan-out and latency.
Ask questions to understand functional and non-functional requirements: number of concurrent editors, document size, offline support, latency expectations, etc.
Outline the main components: client, load balancer, web socket servers, document service, storage, and pub/sub system. Explain data flow.
Discuss how to propagate changes in real-time using WebSockets and a pub/sub system. Address scalability with sharding and consistent hashing.
Explain OT or CRDTs in detail, including how operations are transformed and applied. Compare trade-offs between OT and CRDTs.
Describe how documents are stored (e.g., as a sequence of operations or snapshots), and how to handle versioning and history.
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