Kafka Will Get The Message Across, Guaranteed.

Transcript

1. KAFKA WILL GET THE MESSAGE ACROSS. GUARANTEED. PHP Benelux 2017

   Belgium

2. David Zuelke

3. None

4. dz@heroku.com

5. @dzuelke

6. KAFKA

7. LinkedIn

8. APACHE KAFKA

9. "uh oh, another Apache project?!"

10. None

11. KEEP CALM AND LOOK AT THE WEBSITE

12. None

13. "Basically it is a massively scalable pub/sub message queue. architected

    as a distributed transaction log."

14. "so it's a queue?"

15. it's not just a queue

16. queues are not multi-subscriber :(

17. "so it's a pubsub thing?"

18. it's not just a pubsub thing

19. pubsub broadcasts to all subscribers :(

20. it's a log

21. None

22. not that kind of log

23. WAL

24. Write-Ahead Log

25. WRITE-AHEAD LOG

26. None

27. 1 foo 2 bar 3 baz 4 hi

28. 1 create document: "foo", data: "…" 2 update document: "foo",

    data: "…" 3 create document: "bar", data: "…" 4 remove document: "foo"
29. None

30. never corrupts

31. sequential I/O

32. None

33. sequential I/O

34. every message will be read at least once, no random

    access

35. FileChannel.transferTo (shovels data straight from e.g. disk cache to network

    interface, no copying via RAM)

36. "HI, I AM KAFKA" "Buckle up while we process (m|b|tr)illions

    of messages/s."

37. TOPICS

38. streams of records

39. 1 2 3 4 5 6 7 …

40. 1 2 3 4 5 6 7 8 … producer

    writes consumer reads

41. can have many subscribers

42. 1 2 3 4 5 6 7 8 … producer

    writes consumerB reads consumerA reads

43. can be partitioned

44. P0 1 2 3 4 5 6 7 … P1

    1 2 3 4 … P2 1 2 3 4 5 6 7 8 … P3 1 2 3 4 5 6 …

45. partitions let you scale storage!

46. partitions let you scale consuming!

47. None

48. all records are retained, whether consumed or not, up to

    a configurable limit

49. PRODUCERS

50. byte[]

51. (typically JSON, XML, Avro, Thrift, Protobufs)

52. (typically not funny GIFs)

53. can choose explicit partition, or a key (which is used

    for auto-partitioning)

54. https://github.com/edenhill/librdkafka & https://arnaud-lb.github.io/php-rdkafka/

55. BASIC PRODUCER $rk = new RdKafka\Producer(); $rk->addBrokers("127.0.0.1"); $topic = $rk->newTopic("test");

    $topic->produce(RD_KAFKA_PARTITION_UA, 0, "Unassigned partition, let Kafka choose"); $topic->produce(RD_KAFKA_PARTITION_UA, 0, "Yay consistent hashing", $user->getId()); $topic->produce(1, 0, "This will always be sent to partition 1");

56. CONSUMERS

57. cheap

58. only metadata stored per consumer: offset

59. guaranteed to always have messages in right order (within a

    partition)

60. can themselves produce new messages!
 (but there is also a

    Streams API for pure transformations)
61. None

62. BASIC CONSUMER $conf = new RdKafka\Conf(); $conf->set('group.id', 'myConsumerGroup'); $rk =

    new RdKafka\Consumer($conf); $rk->addBrokers("127.0.0.1"); $topicConf = new RdKafka\TopicConf(); $topicConf->set('auto.commit.interval.ms', 100); $topic = $rk->newTopic("test", $topicConf); $topic->consumeStart(0, RD_KAFKA_OFFSET_STORED); while (true) { $msg = $topic->consume(0, 120*10000); do_something($msg); }

63. AT-MOST ONCE DELIVERY $conf = new RdKafka\Conf(); $conf->set('group.id', 'myConsumerGroup'); $rk

    = new RdKafka\Consumer($conf); $rk->addBrokers("127.0.0.1"); $topicConf = new RdKafka\TopicConf(); $topicConf->set('auto.commit.enable', false); $topic = $rk->newTopic("test", $topicConf); $topic->consumeStart(0, RD_KAFKA_OFFSET_STORED); while (true) { $msg = $topic->consume(0, 120*10000); $topic->offsetStore($msg->partition, $msg->offset); do_something($msg); }

64. AT-LEAST ONCE DELIVERY $conf = new RdKafka\Conf(); $conf->set('group.id', 'myConsumerGroup'); $rk

    = new RdKafka\Consumer($conf); $rk->addBrokers("127.0.0.1"); $topicConf = new RdKafka\TopicConf(); $topicConf->set('auto.commit.enable', false); $topic = $rk->newTopic("test", $topicConf); $topic->consumeStart(0, RD_KAFKA_OFFSET_STORED); while (true) { $msg = $topic->consume(0, 120*10000); do_something($msg); $topic->offsetStore($msg->partition, $msg->offset); }

65. EXACTLY-ONCE DELIVERY

66. you cannot have exactly-once delivery

67. THE BYZANTINE GENERALS "together we can beat the monsters. let's

    both attack at 07:00?" "confirm, we attack at 07:00" ☠

68. USE CASES

69. • LinkedIn • Yahoo • Twitter • Netflix • Square

    • Spotify • Pinterest • Uber • Goldman Sachs • Tumblr • PayPal • Airbnb • Mozilla • Cisco • Etsy • Foursquare • Shopify • CloudFlare

70. ingest the Twitter firehose and turn it into a pointless

    demo ;)
71. None

72. messaging, of course

73. track user activity

74. record runtime metrics

75. aggregate logs

76. IoT
 (you could still e.g. use MQTT over the wire,

    and bridge to Kafka)

77. replicate information between data centers
 (also see Connector API)

78. Event Sourcing broker :)

79. WAL / Commit Log for another system

80. billing!

81. "shock absorber" between systems to avoid overload of DBs, APIs,

    etc.

82. in PHP: mostly producing messages; better languages exist for consuming

83. The End

84. THANK YOU FOR LISTENING! Questions? Ask me: @dzuelke & dz@heroku.com