dataflow-app-kafka is no longer actively maintained by VMware, Inc.

Spring Cloud Stream Application for String Case Transformer with Kafka Binder

This application will consume records from a Kafka topic and then convert its case based on the property case.uppercase. It will produce the transformed String into an outbound Kafka topic.

By default, uppercase transformation is enabled in this application. You can disable it by setting case.uppercase to false.

Using as a template repository

This repository can be used as a template repository for building custom applications that need to use Spring Cloud Stream Kafka binder. The application is already tailored to run on spring cloud data flow.

On the top right hand of this repository on GitHub, find the button Use this template, click on it and follow the instructions. You can find more instructions on how to get started from a template repository by following this guide.

Customizing the application

Since this is a template repository, it is most certain, you need to customize it to build your own business applications. Following are the main components that likely need to be changed.

Business logic

The business logic needs to be customized in the function provided here. The package name may be adjusted. A template for configuration properites are provided here which can be changed altogether to fit custom needs.

Adding or updating maven configuraion

All the versions used for the various dependencies in the application are in the associated maven pom configuration. You can update the versions or add new ones as necessary. The maven configuration also provides various plugins for building the docker image, and the metadata jar that contains the configuration properties to be used on Spring Cloud Data Flow.

Boot properties and metadata

All the Spring Boot properties used in the application are in the file applicaiton.properties which you can further add or update properties to. If you update the function name, make sure to update that in the application.properties file appropriately where it overrides the binding names.

The metadata plugin finds application specific configuration properties by looking for a special file dataflow-configuration-metadata.properties which can be found here. You need to update this file, if you change the configuration properties class name.

Building

./mvnw clean package

Running

You can set the input Kafka topic using the property below:

spring.cloud.stream.bindings.input.destination.

Similarly, for the output topic, use the property spring.cloud.stream.bindings.output.destination.

For example, this is how you run the application for input topic data-in and output topic data-out.

java -jar target/case-processor-kafka-0.0.1-SNAPSHOT.jar --spring.cloud.stream.bindings.input.destination=data-in --spring.cloud.stream.bindings.output.destination=data-out

Docker build

You can also build the docker image for the applicaton as below:

./mvnw clean package jib:build -DskipTests

This builds and pushes the container images to a container registry like Docker Hub. If you just want to build the docker image locally, you can do the following:

./mvnw clean package jib:dockerBuild -DskipTests