Book Image

Apache Kafka Quick Start Guide

By : Raúl Estrada
Book Image

Apache Kafka Quick Start Guide

By: Raúl Estrada

Overview of this book

Apache Kafka is a great open source platform for handling your real-time data pipeline to ensure high-speed filtering and pattern matching on the ?y. In this book, you will learn how to use Apache Kafka for efficient processing of distributed applications and will get familiar with solving everyday problems in fast data and processing pipelines. This book focuses on programming rather than the configuration management of Kafka clusters or DevOps. It starts off with the installation and setting up the development environment, before quickly moving on to performing fundamental messaging operations such as validation and enrichment. Here you will learn about message composition with pure Kafka API and Kafka Streams. You will look into the transformation of messages in different formats, such asext, binary, XML, JSON, and AVRO. Next, you will learn how to expose the schemas contained in Kafka with the Schema Registry. You will then learn how to work with all relevant connectors with Kafka Connect. While working with Kafka Streams, you will perform various interesting operations on streams, such as windowing, joins, and aggregations. Finally, through KSQL, you will learn how to retrieve, insert, modify, and delete data streams, and how to manipulate watermarks and windows.
Table of Contents (10 chapters)

Coding a validator in Java

The Writer class implements the producer interface. The idea is to modify that Writer and build a validation class with minimum effort. The Validator process is as follows:

  • Read the Kafka messages from the input-messages topic
  • Validate the messages, sending defective messages to the invalid-messages topic
  • Write the well-formed messages to valid-messages topic

At the moment, for this example, the definition of a valid message is a message t0 which the following applies:

  • It is in JSON format
  • It contains the four required fields: event, customer, currency, and timestamp

If these conditions are not met, a new error message in JSON format is generated, sending it to the invalid-messages Kafka topic. The schema of this error message is very simple:

{"error": "Failure description" }

The first step is create a new file...