An Interactive Intro to CRDTs

7 hours ago

CRDTs (Conflict-free Replicated Data Types) are data structures that allow peers to update their own state without immediate network synchronization, eventually converging to a single state.
There are two types of CRDTs: state-based (transmit full state) and operation-based (transmit only actions). State-based CRDTs are simpler but require more data transfer.
A CRDT must implement a merge function that is commutative, associative, and idempotent to ensure consistent state across peers.
The Last Write Wins Register (LWW Register) is a simple CRDT that uses timestamps and peer IDs to resolve conflicts, always keeping the last written value.
The Last Write Wins Map (LWW Map) is a more complex CRDT built using LWW Registers for each key, allowing collaborative editing of key-value pairs.
CRDTs use tombstones (null values) to track deletions, ensuring that deletions are correctly propagated and not mistaken for missing keys.
CRDTs are monotonically increasing data structures, meaning they can only add information, not remove it, which can lead to growing state size.
The article demonstrates building a collaborative pixel art editor using CRDTs, showcasing their practical application in real-time collaborative apps.

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