event-store-adapter-kotlin

This library(Kotlin wrapper for j5ik2o/event-store-adapter-java) is designed to turn DynamoDB into an Event Store for CQRS/Event Sourcing.

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Installation

Add the following to your build.gradle.kts.

val version = "..."
dependencies {
// ...
    implementation("com.github.j5ik2o:event-store-adapter-java:${version}")
// ...
}

Or add the following to your build.gradle.

def version = "..."
dependencies {
// ...
    implementation 'com.github.j5ik2o:event-store-adapter-java:${version}'
// ...
}

Usage

You can easily implement an Event Sourcing-enabled repository using EventStore.

class UserAccountRepositoryAsync
  (private val eventStore: EventStoreAsync<UserAccountId, UserAccount, UserAccountEvent>) {

    suspend fun storeEvent(event: UserAccountEvent, version: Long) {
        eventStore.persistEvent(event, version)
    }

    suspend fun storeEventAndSnapshot(event: UserAccountEvent, aggregate: UserAccount) {
        eventStore.persistEventAndSnapshot(event, aggregate)
    }

    suspend fun findById(id: UserAccountId): UserAccount? {
        val userAccount = eventStore
            .getLatestSnapshotById(UserAccount::class.java, id) ?: return null
        val events = eventStore
            .getEventsByIdSinceSequenceNumber(
                UserAccountEvent::class.java, id, userAccount.sequenceNumber + 1)
        return UserAccount.replay(events, userAccount)
    }
}

The following is an example of the repository usage.

val eventStore = EventStoreAsync.ofDynamoDB<UserAccountId, UserAccount, UserAccountEvent>(
    client,
    JOURNAL_TABLE_NAME,
    SNAPSHOT_TABLE_NAME,
    JOURNAL_AID_INDEX_NAME,
    SNAPSHOT_AID_INDEX_NAME,
    32,
)
val userAccountRepository = UserAccountRepositoryAsync(eventStore)

val id = UserAccountId(IdGenerator.generate().toString())

val aggregateAndEvent1 = UserAccount.create(id, "test-1")
val aggregate1 = aggregateAndEvent1.first

userAccountRepository.storeEventAndSnapshot(aggregateAndEvent1.second, aggregate1)

val aggregateAndEvent2 = aggregate1.changeName("test-2")

userAccountRepository.storeEvent(aggregateAndEvent2.second, aggregateAndEvent2.first.version)

val result = userAccountRepository.findById(id)

if (result != null) {
    assertEquals(result.id, aggregateAndEvent1.first.id)
    assertEquals(result.name, "test-2")
} else {
    Assertions.fail<Any>("result is empty")
}

Table Specifications

See docs/DATABASE_SCHEMA.md.

License.

MIT License. See LICENSE for details.

Links

• Common Documents