The technical principles of using the Java class library to implement the Apache Kafka framework.

Interpretation of the technical principles of the Apache Kafka framework using the Java class library Apache Kafka is a high -performance, scalable and persistent distributed flow processing platform, which was initially developed and open source by LinkedIn.Its goal is to provide a reliable, published and subscribing message transmission system that enables applications to efficiently perform data transmission and real -time processing.This article will explain how to use the Java class library to implement the Apache Kafka framework and introduce its technical principles. 1. Apache Kafka's core concept Before starting to discuss how to use the Java library to implement Apache Kafka, you first need to understand some core concepts. 1. News The message is the basic unit in Apache Kafka.It is a record that contains key value pairs that can contain any type of data. 2. Theme The theme is the classification of messages, and each message belongs to a specific theme.The theme can be partitioned to improve the concurrency of the message processing. 3. Partition Division is a physical storage unit of theme.Each theme can be divided into one or more partitions, and each partition has a unique identifier (displacement), which is used to mark the location of the message in the partition. 4. Producer The producer is an entity that publishes the message to the theme.It is responsible for sending the message to the correct theme and partition. 5. Consumers Consumers are entities of consumer messages from the theme.It is responsible for reading from the specified theme and partition. 6. Consumer group Consumer groups are a set of consumers, they consume one or more themes together.In the same consumer group, each partition can only be consumed by one consumer. 2. The steps to use the Java class library to implement Apache Kafka 1. Import dependencies First, in your Java project, you need to add a suitable Kafka client dependencies.You can add the following dependencies in the project construction tool (such as Maven or Gradle): dependencies { implementation 'org.apache.kafka:kafka-clients:2.8.0' } 2. Create producer Using the Kafkaproducer class, you can create a producer for sending messages.First of all, you need to create a Properties object and set up necessary configuration items, such as server addresses, serializers, etc.Then, use these configurations to initialize the KafkapRoducer object. Properties props = new Properties(); props.put("bootstrap.servers", "localhost:9092"); props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer"); props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer"); Producer<String, String> producer = new KafkaProducer<>(props); 3. Send message By calling the Send method of the Producer, you can send the message to the specified theme and partition. String topic = "my-topic"; String key = "key1"; String value = "Hello Kafka"; ProducerRecord<String, String> record = new ProducerRecord<>(topic, key, value); producer.send(record); 4. Create consumers Using the Kafkaconsumer class, you can create a consumer for consumer messages.Similarly, you need to create a Properties object to set the corresponding configuration items. Properties props = new Properties(); props.put("bootstrap.servers", "localhost:9092"); props.put("group.id", "my-consumer-group"); props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer"); props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer"); Consumer<String, String> consumer = new KafkaConsumer<>(props); 5. Subscribe to topic Using the consumer's Subscriper method, you can allow consumers to subscribe to one or more themes. consumer.subscribe(Collections.singletonList("my-topic")); 6. Consumption message By calling the Poll method of Consumer, you can pull messages from the subscribing theme.This is a blocking call, which will return a ConsumerRolds object containing a message record. ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100)); for (ConsumerRecord<String, String> record : records) { System.out.printf("Offset = %d, Key = %s, Value = %s%n", record.offset(), record.key(), record.value()); } 3. Summary This article introduces the technical principles of using the Java library to implement the Apache Kafka framework.You have learned the core concept of Apache Kafka and learned how to use the Java class library to create producers and consumers, sending and consumer news.By understanding these principles and steps, you can better use Apache Kafka to build an efficient and reliable message transmission and flow processing system.