What is a Stream Processor in Apache Kafka ?

A Stream Processor is an application that transforms or processes records from one or more topics together and writes the processed records to one or more topics in the Kafka cluster. Kafka Streams API helps in making an application, a Stream Processor. The processing includes aggregation of events from multiple topics, enrichment of information from topics or only a transformation from one topic to other (like validation or classification of events).

Following is a picture demonstrating the working of Stream Processor in Apache Kafka.

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Stream Processor in Apache Kafka

Typical Stream Processors

Following are some of the stream processors you may find in real-time projects :

  1. Fraudulent Transaction Finder Application – The application reads transactions from the pipeline and writes the fraud transactions (if any) to a Kafka Cluster Topic containing fraud transactions for further processing.
  2. Trend Finder Application – Based on the real-time browsing behaviour of customers online, Stream Processor Application can find the most trending topics and generate suggestions, through aggregation of search items or such.

Stream Processor Example in Apache Kafka

In this Apache Kafka Tutorial, we shall learn Stream Processor in Apache Kafka with a Java Example program. Following is a step by step process to write a simple Stream Processor Example in Apache Kafka.