Dealing with change in event sourced applications (ConFoo 2023)

In software development, change is pretty much the only constant factor. In fact, embracing change is one of the twelve principles behind the Agile Manifesto. However, changing event sourced applications can be very challenging.

In this talk, we’ll explore how to deal with projection updates, event updates and versioning, and existing privacy legislation (such as the GDPR).

Transcript

1. DEALING WITH CHANGE
   

   IN EVENT SOURCED
   APPLICATIONS
   Michiel Rook
   

   @michieltcs
   

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2. @michieltcs
   #StandWithUkraine
   YOU?
   

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3. @michieltcs
   #StandWithUkraine
   FAMILIAR WITH
   CQRS/ES THEORY?
   

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4. @michieltcs
   #StandWithUkraine
   HOBBY PROJECT?
   

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5. @michieltcs
   #StandWithUkraine
   APP IN
   PRODUCTION?
   

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6. @michieltcs
   #StandWithUkraine
   QUICK RECAP
   

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7. @michieltcs
   #StandWithUkraine
   - M A RT I N FOW L E R
   "Event Sourcing ensures that all
   changes to application state are stored
   as a sequence of events."
   

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8. @michieltcs
   #StandWithUkraine
   ACTIVE RECORD VS. EVENT SOURCING
   Account Id
   
   
   Account number Balance
   1234 12345678 € 50,00
   ... ... ...
   Money Withdrawn
   Account Id 1234
   Amount € 50,00
   Money Deposited
   Account Id 1234
   Amount € 100,00
   Account Opened
   Account Id 1234
   Account number 12345678
   

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9. @michieltcs
   #StandWithUkraine
   COMMANDS TO EVENTS
   Deposit Money
   Account Id 1234
   Amount € 100,00
   data class DepositMoney(
   @TargetAggregateIdentifier val accountId: String,
   val amount: BigDecimal
   )
   

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10. @michieltcs
    #StandWithUkraine
    COMMANDS TO EVENTS
    Deposit Money
    Account Id 1234
    Amount € 100,00
    command
    

    handler
    @CommandHandler
    fun depositMoney(command: DepositMoney) {
    apply(MoneyDeposited(
    command.accountId,
    command.amount,
    GenericEventMessage.clock.instant()))
    }
    

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11. @michieltcs
    #StandWithUkraine
    COMMANDS TO EVENTS
    Deposit Money
    Account Id 1234
    Amount € 100,00
    Money Deposited
    Account Id 1234
    Amount € 100,00
    command
    

    handler
    data class MoneyDeposited(
    val accountId: String,
    val amount: BigDecimal,
    val instant: Instant
    )
    

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12. @michieltcs
    #StandWithUkraine
    AGGREGATES
    An Aggregate handles
    Commands and
    generates Events
    based on the current
    state
    

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13. @michieltcs
    #StandWithUkraine
    AGGREGATES
    @Aggregate
    class BankAccount {
    @AggregateIdentifier
    private lateinit var accountId: String
    private lateinit var accountNumber: String
    private lateinit var balance: BigDecimal
    @CommandHandler
    fun depositMoney(command: DepositMoney) {
    apply(MoneyDeposited(
    command.accountId,
    command.amount,
    GenericEventMessage.clock.instant()))
    }
    @EventHandler
    fun moneyDeposited(event: MoneyDeposited) {
    balance = balance.add(event.amount)
    }
    }
    

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14. @michieltcs
    #StandWithUkraine
    AGGREGATE STATE
    Account number Balance
    12345678 € 0,00
    Account number Balance
    12345678 € 100,00
    Account number Balance
    12345678 € 50,00
    event
    

    handler
    event
    

    handler
    event
    

    handler
    Money Withdrawn
    Account Id 1234
    Amount € 50,00
    Money Deposited
    Account Id 1234
    Amount € 100,00
    Account Opened
    Account Id 1234
    Account number 12345678
    

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15. @michieltcs
    #StandWithUkraine
    VALIDATING COMMANDS
    @CommandHandler
    @Throws(OverdraftDetectedException::class)
    fun withdrawMoney(command: WithdrawMoney) {
    if (balance.compareTo(command.amount) >= 0) {
    apply(MoneyWithdrawn(
    command.accountId,
    command.amount,
    GenericEventMessage.clock.instant()))
    } else {
    throw OverdraftDetectedException(accountNumber, balance, command.amount)
    }
    }
    

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16. @michieltcs
    #StandWithUkraine
    TESTING AGGREGATES
    @TestInstance(TestInstance.Lifecycle.PER_CLASS)
    class BankAccountTest {
    private lateinit var fixture: AggregateTestFixture
    @BeforeEach
    fun createFixture() {
    fixture = AggregateTestFixture(BankAccount::class.java)
    }
    @Test
    fun noOverdraftsOnEmptyAccount() {
    fixture.given(accountOpened())
    .`when`(WithdrawMoney(ACCOUNT_ID, WITHDRAW_AMOUNT))
    .expectException(OverdraftDetectedException::class.java)
    }
    const val ACCOUNT_ID = "accountId"
    const val ACCOUNT_NUMBER = "3856625"
    }
    

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17. @michieltcs
    #StandWithUkraine
    THIS IS ABOUT
    
    
    CHANGE
    

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18. @michieltcs
    #StandWithUkraine
    -AG I L E M A N I F ES TO
    "Welcome changing requirements,
    even late in development."
    

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19. @michieltcs
    #StandWithUkraine
    MODIFICATIONS
    

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20. @michieltcs
    #StandWithUkraine
    EVENT SOURCING
    

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21. @michieltcs
    #StandWithUkraine
    CHALLENGE!
    

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22. @michieltcs
    #StandWithUkraine
    REPLAYS AND
    REBUILDS
    

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23. @michieltcs
    #StandWithUkraine
    ANSWERING
    QUERIES
    

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24. @michieltcs
    #StandWithUkraine
    BASED ON EVENTS
    

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25. @michieltcs
    #StandWithUkraine
    QUERIES
    ACCOUNT OPENED
    ACCOUNT OPENED
    ACCOUNT CLOSED Number of active accounts?
    

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26. @michieltcs
    #StandWithUkraine
    QUERIES
    MONEY DEPOSITED
    MONEY WITHDRAWN
    INTEREST RECEIVED
    Accounts with balance > €100?
    MONEY DEPOSITED
    MONEY WITHDRAWN
    

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27. @michieltcs
    #StandWithUkraine
    PROJECTION
    ACCOUNT OPENED EVENT HANDLER
    # OF ACTIVE
    ACCOUNTS +1
    ACCOUNT CLOSED EVENT HANDLER
    # OF ACTIVE
    ACCOUNTS -1
    

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28. @michieltcs
    #StandWithUkraine
    PROJECTION
    EVENTS EVENT HANDLER(S) STORAGE
    

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29. @michieltcs
    #StandWithUkraine
    CQRS
    

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30. @michieltcs
    #StandWithUkraine
    UI
    

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31. @michieltcs
    #StandWithUkraine
    DOMAIN
    UI
    COMMAND HANDLERS
    commands
    AGGREGATES
    

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32. @michieltcs
    #StandWithUkraine
    DOMAIN
    UI
    COMMAND HANDLERS
    REPOSITORY
    EVENT
    STORE
    commands
    events
    AGGREGATES
    

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33. @michieltcs
    #StandWithUkraine
    DOMAIN
    UI
    EVENT BUS
    EVENT HANDLERS
    COMMAND HANDLERS
    REPOSITORY
    DATABASE DATABASE
    EVENT
    STORE
    AGGREGATES
    commands
    events
    events
    

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34. @michieltcs
    #StandWithUkraine
    DOMAIN
    UI
    EVENT BUS
    EVENT HANDLERS
    COMMAND HANDLERS
    REPOSITORY
    DATA LAYER
    DATABASE DATABASE
    EVENT
    STORE
    commands
    events
    events
    queries DTOs
    AGGREGATES
    

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35. @michieltcs
    #StandWithUkraine
    PROJECTION
    class BankAccountProjections {
    private val activeAccounts: MutableMap = HashMap()
    @EventHandler
    fun onAccountOpened(accountOpened: AccountOpened) {
    val bankAccount = BankAccount(
    accountOpened.accountId,
    accountOpened.accountNumber,
    BigDecimal.ZERO)
    activeAccounts[accountOpened.accountId] = bankAccount
    }
    @EventHandler
    fun onAccountClosed(accountClosed: AccountClosed) {
    activeAccounts.remove(accountClosed.accountId)
    }
    

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36. @michieltcs
    #StandWithUkraine
    PROJECTION
    fun findAccountById(accountId: String): Optional {
    return Optional.ofNullable(activeAccounts[accountId])
    }
    fun getNumberOfAccounts(): Int {
    return activeAccounts.size
    }
    }
    

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37. @michieltcs
    #StandWithUkraine
    PROJECTION
    @GetMapping("accounts/{accountId}")
    fun getAccountNumber(@PathVariable("accountId") accountId: String?):
    Optional {
    return bankAccountProjections.findAccountById(accountId!!)
    .map { obj: BankAccount -> obj.accountNumber }
    }
    

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38. @michieltcs
    #StandWithUkraine
    PROJECTION
    @GetMapping("accounts/active")
    fun getNumberOfAccounts(): Int {
    return bankAccountProjections.getNumberOfAccounts()
    }
    

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39. @michieltcs
    #StandWithUkraine
    NEW PROJECTION
    

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40. @michieltcs
    #StandWithUkraine
    NEW STRUCTURE
    

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41. @michieltcs
    #StandWithUkraine
    BASED ON EXISTING
    EVENTS
    

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42. @michieltcs
    #StandWithUkraine
    REBUILDING
    STOP APP CLEANUP
    LOOP OVER
    EVENTS
    APPLY TO
    PROJECTION START APP
    

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43. @michieltcs
    #StandWithUkraine
    ZERO DOWNTIME
    LOOP OVER
    EXISTING EVENTS
    APPLY TO NEW
    PROJECTION USE PROJECTION
    

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44. @michieltcs
    #StandWithUkraine
    ZERO DOWNTIME
    NEW EVENTS QUEUE
    LOOP OVER
    EXISTING EVENTS
    APPLY TO NEW
    PROJECTION
    APPLY QUEUED
    EVENTS USE PROJECTION
    

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45. @michieltcs
    #StandWithUkraine
    LONG RUNNING
    REBUILDS
    

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46. @michieltcs
    #StandWithUkraine
    DISTRIBUTED
    

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47. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    EVENT
    EVENT
    EVENT
    EVENT
    EVENT
    AGGREGATE
    EVENT
    

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48. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    EVENT
    EVENT
    EVENT
    EVENT
    EVENT
    AGGREGATE
    INSTANCE
    EVENT
    INSTANCE
    

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49. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    EVENT
    EVENT
    EVENT
    EVENT
    EVENT
    AGGREGATE
    INSTANCE
    EVENT
    INSTANCE
    

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50. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    EVENT
    EVENT
    EVENT
    EVENT
    EVENT
    AGGREGATE
    INSTANCE
    EVENT
    EVENT
    EVENT
    EVENT
    INSTANCE
    

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51. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    EVENT
    EVENT
    EVENT
    EVENT
    EVENT
    AGGREGATE
    INSTANCE
    EVENT
    EVENT
    EVENT
    INSTANCE
    EVENT
    EVENT
    EVENT
    EVENT
    

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52. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    SELLER LISTING
    Seller Name Listing Date Listing Description
    ... ... ...
    ... ... ...
    ... ... ...
    ... ... ...
    ... ... ...
    ... ... ...
    ... ... ...
    

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53. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    SELLER LISTING
    INSTANCE INSTANCE
    

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54. @michieltcs
    #StandWithUkraine
    DIVIDING THE WORK
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    SELLER EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    LISTING EVENT
    SELLER LISTING
    INSTANCE INSTANCE
    ?
    

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55. @michieltcs
    #StandWithUkraine
    BACKGROUND
    TASKS
    

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56. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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57. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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58. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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59. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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60. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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61. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    TOKEN STORE
    

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62. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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63. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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64. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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65. @michieltcs
    #StandWithUkraine
    TRACKING EVENTS
    EVENT EVENT EVENT EVENT EVENT EVENT . . . . . . . . . . . . . .
    EVENT
    EVENT
    EVENT
    

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66. @michieltcs
    #StandWithUkraine
    TRACKING EVENT PROCESSOR
    GET NEXT EVENT
    APPLY TO NEW
    PROJECTION
    LAST EVENT? USE PROJECTION
    yes
    no
    

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67. @michieltcs
    #StandWithUkraine
    TRACKING EVENT PROCESSOR
    @Target(AnnotationTarget.CLASS)
    @Retention(AnnotationRetention.RUNTIME)
    annotation class RebuildableProjection(
    val version: String = "",
    val rebuild: Boolean = false
    )
    

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68. @michieltcs
    #StandWithUkraine
    TRACKING EVENT PROCESSOR
    @Autowired
    fun startTrackingProjections(configurer: EventProcessingConfigurer) {
    val scanner = ClassPathScanningCandidateComponentProvider(false)
    scanner.addIncludeFilter(AnnotationTypeFilter(RebuildableProjection::class.java))
    for (bd in scanner.findCandidateComponents("org.demo")) {
    val projectionClass = Class.forName(bd.beanClassName)
    val rebuildableProjection =
    projectionClass.getAnnotation(RebuildableProjection::class.java)
    if (rebuildableProjection.rebuild) {
    registerRebuildableProjection(
    configurer,
    projectionClass,
    rebuildableProjection)
    }
    }
    }
    

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69. @michieltcs
    #StandWithUkraine
    TRACKING EVENT PROCESSOR
    private fun registerRebuildableProjection(configurer: EventProcessingConfigurer,
    projectionClass: Class<*>,
    rebuildableProjection: RebuildableProjection) {
    val processingGroup = projectionClass.getAnnotation(ProcessingGroup::class.java)
    val name = processingGroup?.let(ProcessingGroup::value)
    ?: (projectionClass.name + "/" + rebuildableProjection.version)
    configurer.assignHandlerTypesMatching(name) { eventHandler ->
    projectionClass.isAssignableFrom(ClassUtils.getUserClass(eventHandler))
    }
    configurer.registerTrackingEventProcessor(name)
    }
    

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70. @michieltcs
    #StandWithUkraine
    TRACKING EVENT PROCESSOR
    trackingEventProcessor.shutDown()
    trackingEventProcessor.resetTokens()
    trackingEventProcessor.start()
    

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71. @michieltcs
    #StandWithUkraine
    TRACKING EVENT PROCESSOR
    class BankAccountProjections {
    private val activeAccounts: MutableMap = HashMap()
    @ResetHandler
    fun resetProjections() {
    activeAccounts.clear()
    }
    ////

    }
    

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72. @michieltcs
    #StandWithUkraine
    EVENT VERSIONING
    

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73. @michieltcs
    #StandWithUkraine
    NEW BUSINESS
    REQUIREMENTS
    

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74. @michieltcs
    #StandWithUkraine
    CHANGING VIEW ON
    EVENTS
    

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75. @michieltcs
    #StandWithUkraine
    IRRELEVANT
    

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76. @michieltcs
    #StandWithUkraine
    DIFFERENT FIELDS
    

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77. @michieltcs
    #StandWithUkraine
    WRONG NAME
    

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78. @michieltcs
    #StandWithUkraine
    TOO COARSE
    

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79. @michieltcs
    #StandWithUkraine
    TOO FINE
    

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80. @michieltcs
    #StandWithUkraine
    HOW TO SUPPORT
    YOUR LEGACY?
    

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81. @michieltcs
    #StandWithUkraine
    Commands
    can be
    renamed
    1
    

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82. @michieltcs
    #StandWithUkraine
    Commands
    can be
    renamed
    1
    Events are
    immutable
    2
    

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83. @michieltcs
    #StandWithUkraine
    Commands
    can be
    renamed
    1
    Events are
    immutable
    Correct old
    events with
    new events
    2 3
    

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84. @michieltcs
    #StandWithUkraine
    Ledger Entry
    Aug 14 Inventory € 15600,00
    Accounts Payable € 15600,00
    

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85. @michieltcs
    #StandWithUkraine @michieltcs
    Ledger Entry
    Aug 14 Inventory € 15600,00
    Accounts Payable € 15600,00
    Ledger Entry
    Aug 14 Inventory € 16500,00
    Accounts Payable € 16500,00
    

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86. @michieltcs
    #StandWithUkraine
    Ledger Entry
    Aug 14 Inventory € 15600,00
    Accounts Payable € 15600,00
    Ledger Entry
    Aug 14 Inventory € 16500,00
    Accounts Payable € 16500,00
    Ledger Correction Entry
    Aug 14 Inventory € 900,00
    Accounts Payable € 900,00
    

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87. @michieltcs
    #StandWithUkraine
    COMPENSATING ACTIONS
    class MoneyWithdrawn {

    String accountId;

    BigDecimal amount;

    }
    class WithdrawalRolledBack {

    String accountId;

    BigDecimal amount;

    }
    Typo: too much withdrawn!
    

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88. @michieltcs
    #StandWithUkraine
    COMPENSATING ACTIONS
    class AccountOpened {

    String accountId;

    String accountNumber;

    }
    class DuplicateAccountClosed {

    String accountId;

    }
    Duplicate account number!
    

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89. @michieltcs
    #StandWithUkraine
    UPCASTING
    

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90. @michieltcs
    #StandWithUkraine
    UPCASTING
    EVENT STORE
    OLD EVENT TYPE
    UPCASTER
    NEW EVENT TYPE
    EVENT HANDLER
    

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91. @michieltcs
    #StandWithUkraine
    UPCASTING
    EVENT STORE
    

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92. @michieltcs
    #StandWithUkraine
    UPCASTING
    @Revision("1.0")
    data class AccountOpened(
    val accountId: String,
    val accountNumber: String
    )
    

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93. @michieltcs
    #StandWithUkraine
    UPCASTING
    
    

    80f49161
    

    12345678
    
    
    
    

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94. @michieltcs
    #StandWithUkraine
    UPCASTING
    EVENT STORE
    ACCOUNTOPENED (1.0)
    EVENT HANDLER
    

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95. @michieltcs
    #StandWithUkraine
    UPCASTING
    @Revision("2.0")
    data class AccountOpened(
    val accountId: String,
    val accountNumberIban: String
    )
    

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96. @michieltcs
    #StandWithUkraine
    UPCASTING
    
    

    80f49161
    

    NL00ABNA012345678
    

    
    

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97. @michieltcs
    #StandWithUkraine
    UPCASTING
    EVENT STORE
    ACCOUNTOPENED (1.0)
    UPCASTER
    ACCOUNTOPENED (2.0)
    EVENT HANDLER
    

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98. @michieltcs
    #StandWithUkraine
    UPCASTING
    class AccountOpenedUpcaster : SingleEventUpcaster() {
    private val typeConsumed = SimpleSerializedType("AccountOpened", "1.0")
    private val typeProduced = SimpleSerializedType("AccountOpened", "2.0")
    override fun canUpcast(intermediateRepresentation:
    IntermediateEventRepresentation): Boolean {
    return intermediateRepresentation.type == typeConsumed
    }
    override fun doUpcast(intermediateRepresentation:
    IntermediateEventRepresentation): IntermediateEventRepresentation {
    return intermediateRepresentation.upcastPayload(
    typeProduced,
    JsonNode::class.java
    ) { event: JsonNode ->
    val node = event as ObjectNode
    val accountNumber = node["accountNumber"].asText()
    node.put("accountNumberIban", toIban(accountNumber))
    node.remove("accountNumber")
    event
    }
    }
    

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99. @michieltcs
    #StandWithUkraine
    VERSIONED EVENT
    STORE
    

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100. @michieltcs
     #StandWithUkraine
     events_v1
     [

     {

     "id": "12345678",

     "type": "AccountOpened",

     "aggregateType": "Account",

     "aggregateIdentifier": "1234",

     "sequenceNumber": 0,

     "payloadRevision": "1.0",

     "payload": { ... },

     "timestamp": ...

     ...

     },

     ...

     ]
     

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101. @michieltcs
     #StandWithUkraine
     COPY & REPLACE
     

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102. @michieltcs
     #StandWithUkraine
     VERSIONED EVENT STORE
     LOOP OVER
     EXISTING EVENTS APPLY UPCASTER
     ADD QUEUED
     EVENTS
     USE NEW EVENT
     STORE
     NEW EVENTS QUEUE
     

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103. @michieltcs
     #StandWithUkraine
     events_v2
     [

     {

     "id": "12345678",

     "type": "AccountOpened",

     "aggregateType": "Account",

     "aggregateIdentifier": "1234",

     "sequenceNumber": 0,

     "payloadRevision": "2.0",

     "payload": { ... },

     "timestamp": ...

     ...

     },

     ...

     ]
     

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104. @michieltcs
     #StandWithUkraine
     GDPR
     

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105. @michieltcs
     #StandWithUkraine
     "RIGHT TO
     ERASURE"
     

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106. @michieltcs
     #StandWithUkraine
     - G D P R , A RT I C L E 17
     "... shall have the right to obtain ...
     the erasure of personal data
     concerning him or her without undue
     delay"
     

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107. @michieltcs
     #StandWithUkraine
     PERSONALLY
     IDENTIFIABLE
     INFORMATION
     

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108. @michieltcs
     #StandWithUkraine
     REMOVED
     

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109. @michieltcs
     #StandWithUkraine
     ANONYMIZED?
     

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110. @michieltcs
     #StandWithUkraine
     PROCESSING GDPR ART. 17 REQUESTS
     RIGHTTOERASUREINVOKED
     REMOVE FROM
     EVENT STORE
     REMOVE FROM
     READ MODELS
     NOTIFY 3RD
     PARTIES
     

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111. @michieltcs
     #StandWithUkraine
     PROCESSING GDPR ART. 17 REQUESTS
     RIGHTTOERASUREINVOKED
     REMOVE FROM
     EVENT STORE
     ?
     REMOVE FROM
     READ MODELS
     NOTIFY 3RD
     PARTIES
     

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112. @michieltcs
     #StandWithUkraine
     IMMUTABLE
     EVENTS?
     

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113. @michieltcs
     #StandWithUkraine
     MODIFY DIRECTLY
     

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114. @michieltcs
     #StandWithUkraine
     COPY WITH FILTER
     

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115. @michieltcs
     #StandWithUkraine
     STORE PII
     EXTERNALLY
     

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116. @michieltcs
     #StandWithUkraine
     STORE PII EXTERNALLY
     ACCOUNTOPENED EXTERNAL STORAGE
     Account Id
     
     
     Account number Name
     1234 12345678 John Doe
     ... ... ...
     data class AccountOpened(
     @TargetAggregateIdentifier

     val accountId: String
     )
     

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117. @michieltcs
     #StandWithUkraine
     CRYPTO SHEDDING
     

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118. @michieltcs
     #StandWithUkraine
     ENCRYPTING EVENTS
     
     

     80f49161
     

     NL00ABNA012345678
     

     Foo
     

     Bar
     
     
     ...
     

     
     

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119. @michieltcs
     #StandWithUkraine
     ENCRYPTING EVENTS
     
     

     80f49161
     

     2dqjHkY8Mc8+cek4vs/9hzgkob4J3fZJNIJh2sAXlJ0=
     accountNumberIban>
     

     N5Y27vd0UbKo6FIu5c7QGQ==
     

     OSKrzfuuuayuUNXYS5YUug==
     
     
     ...
     

     
     

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120. @michieltcs
     #StandWithUkraine
     ENCRYPTING EVENTS
     GENERATE
     EVENT
     FIND /
     CREATE
     ENCRYPTION
     KEY
     ENCRYPT
     PAYLOAD
     VALUES
     STORE
     

     EVENT
     

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121. @michieltcs
     #StandWithUkraine
     DECRYPTING EVENTS
     LOAD
     

     EVENT
     FIND
     ASSOCIATEDENC
     RYPTION KEY
     DECRYPT
     PAYLOAD
     VALUES
     PROCESS
     

     EVENT
     

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122. @michieltcs
     #StandWithUkraine
     SHEDDING THE KEY
     LOAD
     

     EVENT
     FIND
     ASSOCIATEDENC
     RYPTION KEY
     DECRYPT
     PAYLOAD
     VALUES
     PROCESS
     

     EVENT
     X
     

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123. @michieltcs
     #StandWithUkraine
     OPTIONS
     https://developer.axoniq.io/axon-data-protection/overview
     
     
     https://github.com/everest-engineering/axon-crypto-shredding-extension
     

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124. @michieltcs
     #StandWithUkraine
     CLOSING WORDS
     

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125. @michieltcs
     #StandWithUkraine
     NO SILVER BULLET
     

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126. @michieltcs
     #StandWithUkraine
     LOTS OF
     CHALLENGES
     

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127. @michieltcs
     #StandWithUkraine
     (IM)MUTABILITY
     

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128. @michieltcs
     #StandWithUkraine
     AUDIT TRAIL
     

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129. @michieltcs
     #StandWithUkraine
     SCALABILITY
     

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130. @michieltcs
     #StandWithUkraine
     TESTING
     

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131. @michieltcs
     @michieltcs
     #StandWithUkraine
     THANK YOU FOR
     LISTENING!
     
     
     twitter: @michieltcs
     

     mastodon: @michielrook@mastodon.nl
     

     email: michiel@michielrook.nl
     
     
     www.michielrook.nl
     

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