Kafka是一个分布式流处理平台,主要用于构建实时数据流管道和应用程序。尽管Kafka不是一个专门的双向消息传递系统,但你可以通过一些方法实现类似双向通信的功能。
在这种模式下,客户端发送一个请求到Kafka主题,然后等待另一个主题上的响应。这需要两个主题:一个用于请求,另一个用于响应。
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);
ProducerRecord<String, String> record = new ProducerRecord<>("request-topic", "request-key", "request-value");
producer.send(record);
Properties consumerProps = new Properties();
consumerProps.put("bootstrap.servers", "localhost:9092");
consumerProps.put("group.id", "response-group");
consumerProps.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
consumerProps.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
KafkaConsumer<String, String> consumer = new KafkaConsumer<>(consumerProps);
consumer.subscribe(Arrays.asList("response-topic"));
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());
}
另一个服务或组件监听request-topic
,处理请求并将响应发送到response-topic
。
Properties producerProps = new Properties();
producerProps.put("bootstrap.servers", "localhost:9092");
producerProps.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
producerProps.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
Producer<String, String> responseProducer = new KafkaProducer<>(producerProps);
ProducerRecord<String, String> responseRecord = new ProducerRecord<>("response-topic", "response-key", "response-value");
responseProducer.send(responseRecord);
Kafka Streams是一个客户端库,用于构建应用程序和微服务,其中输入和输出数据存储在Kafka集群中。你可以使用Kafka Streams实现更复杂的双向通信逻辑。
StreamsBuilder builder = new StreamsBuilder();
KStream<String, String> inputStream = builder.stream("input-topic");
KStream<String, String> outputStream = inputStream.mapValues(value -> "response-" + value);
outputStream.to("output-topic");
KafkaStreams streams = new KafkaStreams(builder.build(), props);
streams.start();
在Kafka Streams应用程序中,你可以使用KStream
和KTable
等API处理双向通信逻辑。
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