Kafka Basic Use Method (Java)

Kafka Basic Use Method (Java).

procedure:

Create topic

$ cd/opt/cloudera/parcels/kafka-2.1.1-1.2.1.1.p0.18 $ bin/kafka-topics--create--zookeeper localhost:2181- Replication-factor 1--partitions 1--topic test

Analysis: Although Kafka's Open API does not establish a topic approach, experiments have shown that a corresponding topic is automatically created when producer sends a new topic message to broker.
However, the automatically established topic uses the default configuration and manually modifies the configuration if necessary.

Send data to Kafka

$ bin/kafka-console-producer--broker-list xxx.xxx.xxx.xxx:9092--topic test

(Messages in the red box need to be entered manually)
Analysis: Kafka data interaction with producer and consumer by default via port 9092. When used formally, this step is replaced by a producer-side script.

Establish consumer consumption data

$ bin/kafka-console-consumer--zookeeper xxx.xxx.xxx.xxx:2181--bootstrap-server xxx.xxx.xxx.xxx:9092--topic Test--from-beginning

Analysis: Successfully read the data in test. When used formally, this step is replaced by a consumer-side script.

Problem Summary:

Don't use localhost!!!.

Problem reappearance: Start with the official document guidelines, use the command to build a test producer

$ bin/kafka-console-producer.sh--broker-list localhost:9092--topic test

The

result appears as an issue in the previous illustration:
Org.apache.kafka.common.errors.TimeoutException:
Failed to update metadata after 60000 Ms.
for this question to make a guess: that the problem is zookeeper for a certain IP restrictions on the above, in other words, the official documents in the demo should be in a stand-alone environment, at this time zookeeper and Kafka on the same machine, Zookeeper has permission to update metadata on the machine localhost, and in the use of multi-node clusters, zookeeper disables the corresponding permissions of localhost in order to prevent deviations from transmission.
to verify the above conjecture, you need to test in a stand-alone environment, there is no time to do. Let's talk about it. (╯_╰) ╭
Workaround: Switch to a specific IP, it is so simple, but the problem has been looking for a long time, a little way all wood.
Summary: Don't use localhost!! It is necessary to familiarize yourself with the principles of zookeeper.