gamussa / kafka-clients-kotlin

Kafka Clients library for Kotlin

Kafka Clients for Kotlin

Warning

Be aware that this package is still in heavy development. Some breaking change will occur in future weeks and months. Thank's for your comprehension.

What is Kafka Clients for Kotlin ?

The Kafka Client for Kotlin projects packs with convenient Kotlin API for the development of Kafka-based event-driven applications. It provides high-level abstractions both for sending records (ProducerContainer) and consuming records from topics using one or many concurrent consumers (KafkaConsumerWorker).

For Maven

<dependency>
  <groupId>io.streamthoughts</groupId>
  <artifactId>kafka-clients-kotlin</artifactId>
  <version>0.1.0</version>
</dependency>

Getting Started

Kafka Producer

val producer: ProducerContainer<String, String> = kafka("localhost:9092") {
    client {
        clientId("my-client")
    }

    producer {
        configure {
            acks(Acks.InSyncReplicas)
        }
        keySerializer(StringSerializer())
        valueSerializer(StringSerializer())

        defaultTopic("demo-topic")

        onSendSuccess{ _, _, metadata ->
            println("Record was sent successfully: topic=${metadata.topic()}, partition=${metadata.partition()}, offset=${metadata.offset()} ")
        }
    }
}

with(producer) {
    init()
    listOf("I ❤️ Logs", "Making Sense of Stream Processing", "Apache Kafka").forEach {
        send(value = it)
    }
    close()
}

Kafka Consumer

val consumerWorker: ConsumerWorker<String, String> = kafka("localhost:9092") {
    client {
        clientId("my-client")
    }

    val stringDeserializer: Deserializer<String> = StringDeserializer()
    consumer("my-group", stringDeserializer, stringDeserializer) {
        configure {
            maxPollRecords(1000)
            autoOffsetReset(AutoOffsetReset.Earliest)
        }

        onDeserializationError(DeserializationErrorHandlers.silentlyReplaceWithNull())

        onPartitionsAssigned { _: Consumer<*, *>, partitions ->
            println("Partitions assigned: $partitions")
        }

        onPartitionsRevokedAfterCommit { _: Consumer<*, *>, partitions ->
            println("Partitions revoked: $partitions")
        }

        onConsumed { _: Consumer<*, *>, value: String? ->
            println("consumed record-value: $value")
        }

        Runtime.getRuntime().addShutdownHook(Thread { run { stop() } })
    }
}
consumerWorker.start("topic-test", maxParallelHint = 4)

Licence

Copyright 2020 StreamThoughts.

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License