Reactsf 2014-message-driven
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To Be Message Driven from React SF 2014
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Reactsf 2014-message-driven
- 1. To Be Message-Driven Todd L. Montgomery @toddlmontgomery
- 2. Life is Message Driven
- 5. CPUs are Message Driven
- 9. Browsers are “Message” Driven
- 11. Why is this?
- 12. The most scalable, resilient, & fast systems seem to follow some common principles…
- 15. It’s not what Message Passing provides…
- 16. It’s what Message Passing makes harder or even impossible
- 17. Boundaries
- 20. Asynchronous Boundary Forced Decoupling Binary Boundary & Separation of Concerns Ordering Errors as Messages
- 22. Asynchronous
- 23. Request Response @toddlmontgomery Processing Could do stuff while waiting!
- 24. Waiting at the mailbox…
- 25. Even traditional blocking operations can be decoupled
- 26. @toddlmontgomery Async Requests & Responses Request Request Request Response Response Response
- 27. Request 0 Request 1 Request 2 Response 0 Response 1 Response 2 @toddlmontgomery Async Requests & Responses Correlation!
- 28. Request 0 Request 1 Request 2 Response 0 Response 1 Response 2 Ordering Correlation! @toddlmontgomery
- 29. Request 0 Response 0 Request 1 Response 1 Request 2 Response 2 Correlation! @toddlmontgomery (Valid) Re-Ordering
- 30. Request 0 Response 1 Invalid, Drop We only know of 0. Handling the Unexpected @toddlmontgomery 1 is unknown!
- 31. Binary
- 32. .addPayment(5) Without a binary boundary, too easy to couple & conflate
- 33. struct PaymentMessage { std::int32_t accountId; std::int32_t amount; }; When all you have is binary, harder to couple and/or conflate
- 34. Ordering
- 35. Packets, nay Messages!, Can Be… Duplicated Re-Ordered Lost
- 38. TCP connections can… be closed unexpectedly end in an unknown state be intercepted by idiots, er Proxies
- 39. Which means Data over TCP* might be… Duplicated Re-Ordered Lost * - When connections are re-established
- 40. Ordering is an Illusion!!
- 41. Compiler can re-order Runtime can re-order CPU can re-order
- 42. Which is why Lock-Free Programming shares some behaviors with Protocols…
- 43. Java x86 C++11 http://en.wikipedia.org/wiki/Memory_ordering
- 44. Source Ordering Message A and B from same source are ordered
- 45. Illusion of Ordering… bordering on “Delusion” Total Ordering Message A and B from any 2+ sources are ordered the same at all destinations
- 46. Causal Ordering Message A and B from any source are ordered if B causally relates to A
- 47. Ordering can just fall out
- 48. Application Layer Framing 0 X bytes 0 1 2 3 4 5 6 7 8 0 1 3 4 5 6 7 2 8 S: R: File to Transfer Recover Dead Reckoning about Ordering! Clark and Tennenhouse, ACM SIGCOMM CCR, Volume 20, Issue 4, Sept. 1990
- 49. Most of the time, Ordering simply isn’t enough
- 50. Messages Can Be… Duplicated Re-Ordered Lost
- 52. Transition Table? JavaScript prototypes? Java enums? Table with Lambdas!?
- 53. public void onAck(final Event ev) { switch (currentState) { … case State.FIN_WAIT_1: // an ACK while in FIN_WAIT_1 currentState = State.FIN_WAIT_2; break; … } } Event Current State Next State State & Events be explicit, do not hide behind abstraction(s) Make them Observable!
- 54. State Machines… worth your time
- 55. RST Simultaneous Open Closing & Dupes, etc.
- 56. State Machine Testing 1. Does my “code” implement it correctly? 2. Is my design safe, correct, etc.? VLSI Testing Techniques e.g. ARC/Branch Testing
- 57. Model Checking
- 58. 2002 ACM System Software Award SPIN http://en.wikipedia.org/wiki/SPIN_model_checker
- 61. Idempotent Unit of Work ADU 1. Little to no ordering requirement 2. Little to no state requirement e.g. REST That stateless bit…
- 62. Responsive No/Less waiting & No/Less contention…
- 63. Resilient No/Less waiting & No/Less state…
- 64. Elastic No contention, no shared state…
- 65. Because Amdahl will hunt you down
- 67. @toddlmontgomery Questions? • Reactive Manifesto http://www.reactivemanifesto.com • Kaazing http://www.kaazing.com • SlideShare http://www.slideshare.com/toddleemontgomery • Twitter @toddlmontgomery Thank You!