Convergence versus Consensus: CRDTs and the Quest for Distributed Consistency

Convergence versus Consensus: CRDTs and the Quest for Distributed Consistency

Slides from a talk given on 5 March 2018 at QCon London.
https://qconlondon.com/london2018/presentation/crdts-and-quest-distributed-consistency

Abstract:

We all know how to build applications that rely on a central server. However, such centralisation is not always desirable, and recently there has been new interest in developing decentralised applications. Blockchains inevitably come up in that conversation, but when you examine them critically, not every problem is best solved by a blockchain.

In this talk we will explore how to ensure data consistency in distributed systems, especially in systems that don't have an authoritative leader. We will see how to sync data between your phone and your laptop without sending it via a remote server. We will explore algorithms that allow several people to collaborate on a shared document, communicating via a peer-to-peer network.

Conflict-Free Replicated Datatypes (CRDTs) are a set of algorithms that ensure data consistency in such settings. Recent research on CRDTs has enabled us to better understand their consistency guarantees and design richer datatypes. On the practical side, CRDTs are making their way into more and more applications. This talk will examine that research and its uses, showing where we are now and where we are heading in the future.

0d4ef9af8e4f0cf5c162b48ba24faea6?s=128

Martin Kleppmann

March 05, 2018
Tweet

Transcript

  1. None
  2. None
  3. None
  4. https://www.ucu.org.uk/why-we-are-taking-action-over-USS

  5. None
  6. None
  7. None
  8. None
  9. None
  10. None
  11. None
  12. None
  13. None
  14. None
  15. None
  16. None
  17. None
  18. None
  19. None
  20. None
  21. None
  22. None
  23. None
  24. None
  25. None
  26. None
  27. None
  28. None
  29. None
  30. None
  31. None
  32. None
  33. None
  34. None
  35. None
  36. None
  37. None
  38. None
  39. None
  40. None
  41. None
  42. None
  43. None
  44. None
  45. None
  46. None
  47. For details, see our paper at https://doi.org/10.1145/3133933 Victor B. F.

    Gomes, Martin Kleppmann, Dominic P. Mulligan, and Alastair R. Beresford: Verifying Strong Eventual Consistency in Distributed Systems. PACMPL 1(OOPSLA), 2017.
  48. None
  49. None
  50. None
  51. Trellis, a Trello clone based on Automerge: https://github.com/automerge/trellis Joint work

    with Orion Henry, Peter van Hardenberg, Roshan Choxi, and Adam Wiggins.
  52. None
  53. Pixelpusher, a collaborative pixel art editor: https://github.com/automerge/pixelpusher Created by Javier

    Valencia, Jeff Peterson, Peter van Hardenberg, and Jim Pick.
  54. None
  55. None
  56. MPL, a WebRTC network layer for Automerge: https://github.com/automerge/mpl Joint work

    with Orion Henry, Peter van Hardenberg, Roshan Choxi, and Adam Wiggins.
  57. Hypermerge, a peer-to-peer network layer: https://github.com/automerge/hypermerge Created by Jim Pick,

    Jeff Peterson, and Peter van Hardenberg.
  58. None
  59. None
  60. None
  61. None
  62. None
  63. None
  64. None
  65. None
  66. None
  67. None
  68. None
  69. None
  70. None
  71. None
  72. None
  73. None
  74. None
  75. None
  76. None
  77. None
  78. None
  79. None
  80. None
  81. None
  82. None
  83. None
  84. None
  85. None
  86. None
  87. None
  88. None
  89. None
  90. None
  91. None
  92. None
  93. None
  94. None
  95. None
  96. None
  97. None
  98. None
  99. None
  100. Resources • Automerge: https://github.com/automerge/automerge • Trellis: https://github.com/automerge/trellis • Pixelpusher: https://github.com/automerge/pixelpusher

    • MPL (WebRTC layer): https://github.com/automerge/mpl • Hypermerge: https://github.com/automerge/hypermerge • Dat / Hypercore: https://datproject.org/ • Proving CRDTs correct: https://doi.org/10.1145/3133933 • JSON CRDT: http://arxiv.org/abs/1608.03960 • My book: http://dataintensive.net/
  101. None