The article "An Interactive Intro to CRDTs" by Jake Lazaroff provides an accessible introduction to Conflict-free Replicated Data Types (CRDTs), explaining their significance in building collaborative applications. Starting from basic concepts, the author explains what CRDTs are—data structures that allow multiple peers to update their states independently while ensuring eventual consistency. It distinguishes between state-based CRDTs, which send their entire state for merging, and operation-based CRDTs, which send only updates. The article further introduces the Last Write Wins (LWW) Register and LWW Map, detailing how both implement the CRDT interface consisting of a value, state, and a merge function. These elements facilitate the development of applications, such as a collaborative pixel art editor, ensuring updates do not require a central server while maintaining reliability across distributed systems.

Key Points:

• CRDTs (Conflict-free Replicated Data Types) allow multiple peers to independently update data while eventually achieving a consistent state.
• Two types of CRDTs: state-based (full state merging) and operation-based (merging based on updates).
• The article focuses on state-based CRDTs and specifically on the Last Write Wins Register (LWW Register).
• LWW Registers utilize timestamps to determine the most recent write and merge states accordingly.
• The LWW Map allows for managing multiple values, essentially serving as a mapping of keys to LWW Registers, maintaining consistency even with concurrent updates.
• CRDTs are monotonically increasing data structures, which means they can only add data, not remove it entirely.
• The next article will showcase how to apply these CRDT principles in building a collaborative pixel art editor.
  Link to Article