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CRDTs and Operational Transform

·1 min
  • CRDTs and Operational Transform algorithms both try to achieve the same purpose: how to support Google Doc style collaborative edits?
  • OTs require a central server whereas CRDTs allow decentralization. The latter is important in cases where you just want to sync your mobile phone with computer when they are offline: Google Doc doesn’t support that.
  • Automerge, a library implementation of CRDTs, supports a neat algorithm to ensure convergence: conflicts are unavoidable in some situations but, at the minimum, all parties should converge to one version.
    • Only supports data structures: network transport is a separate concern and can vary.
    • I think you only transport operations within participants, not the state. Participants arrive at common state when they apply their own and incoming operations.
  • The order in which operations are applied doesn’t matter: end state will be consistent.