Kafka Introduction Series—2. Topic creation and storage

1. First start zookeeper and kafka

• Start zookeeper in the foreground

  bin/zkServer.sh start-foreground
  

• Start kafka

   bin/kafka-server-start.sh config/server.properties
  

2. Topic command line tool

You must specify topic when sending messages to or receiving messages from Kafka .

The following command can view the existing topics in Kafka:

 

bin/kafka-topics.sh --zookeeper localhost:2181 --list

The --zookeeper localhost:2181parameters are required.

• Create a topic( --create)

   bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic testtopic
  

You can view after creating testtopic

• View topic information ( --describe)

   bin/kafka-topics.sh --describe --topic testtopic --zookeeper localhost:2181
  

Testtopic information: 1 partition, 1 copy

You can see that the number of partitions is 1, and the replicationfactor is 1, because the parameters specified when creating testtopic are as follows:

 

--replication-factor 1 --partitions 1 

3. Data stored in zookeeper

Kafka topic information is stored in zookeeper.

• Use the zkCli.shcommand line tool to connect to the zookeeper server.

  bin/zkCli.sh -server localhost:2181
  

• Zookeeper is a tree structure with a root node /. The following command can view all the child nodes under the root node.

Child nodes under the zookeeper root node

• The topic information is stored in the /config/topicspath, and you can see the testtopic just created.

  ls /config/topics
  

Topics stored in zookeeper