{"id":14722,"date":"2018-04-28T13:25:53","date_gmt":"2018-04-28T13:25:53","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=14722"},"modified":"2018-04-28T13:25:53","modified_gmt":"2018-04-28T13:25:53","slug":"kafka-consumer","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/kafka-consumer\/","title":{"rendered":"Apache Kafka Consumer | Kafka Consumer Group"},"content":{"rendered":"

In our last article, we discussed Kafka Producer<\/strong>. Today, we will discuss Kafka Consumer. Firstly, we will see what is Kafka Consumer and example of Kafka Consumer. Afterward, we will learn Kafka Consumer Group.<\/p>\n

Moreover, we will see Consumer record API and configurations setting for Kafka Consumer.
\nAfter creating a Kafka Producer to send messages to Apache Kafka<\/strong> cluster. Now, we are creating a Kafka Consumer to consume messages from the Kafka cluster.<\/span><\/p>\n

So, let’s discuss Kafka Consumer in detail.<\/p>\n

What is Kafka Consumer?<\/span><\/h2>\n

An application that reads data from Kafka Topics<\/strong> is what we call a Consumer. Basically, Kafka Consumer subscribes to one or more topics in the Kafka cluster then further feeds on tokens or messages from the Kafka Topics.\u00a0<\/span><\/p>\n

In addition, using Heartbeat we can know the connectivity of Consumer to Kafka Cluster<\/strong>. However, let\u2019s define Heartbeat. It is set up at Consumer to let Zookeeper or Broker Coordinator know if the Consumer is still connected to the Cluster.<\/p>\n

So, Kafka Consumer is no longer connected to the Cluster, if the heartbeat is absent. In that case, the Broker Coordinator has to re-balance the load.<\/p>\n

Moreover, Heartbeat is an overhead to the cluster. Also, by keeping the data throughput and overhead in consideration, we can configure the interval at which the heartbeat is at Consumer.<\/p>\n

\"Apache<\/a>

What is Apache Kafka Consumer<\/p><\/div>\n

Moreover, we can group the consumers, and the consumers in the Consumer Group in Kafka could share the partitions of the Kafka Topics they subscribed to. T<\/span><\/p>\n

o understand see, if there are N partitions in a Topic, N consumers in the Kafka Consumer Group and the group has subscribed to a Topic, each consumer would read data from a partition of the topic. <\/span><\/p>\n

Hence, we can say, this is just a heads up that Consumers could be in groups.<\/span><\/p>\n

To be specific, to connect to the Kafka cluster and consume the data streams, the Consumer API from Kafka helps.<\/span><\/p>\n

Below is the picture showing Apache Kafka Consumer:<\/span><\/p>\n

\"Working<\/a>

Working of Apache Kafka Consumer<\/p><\/div>\n

To subscribe to one or more topics and process the stream of records produced to them in an application, we use this Kafka Consumer API. In order words, we use KafkaConsumer API to consume messages from the Kafka cluster. Moreover, below see the KafkaConsumer class constructor.<\/span><\/p>\n

public KafkaConsumer(java.util.Map<java.lang.String,java.lang.Object> configs)<\/pre>\n