Spring Cloud Data Flow With Spring Boot | Spring Cloud Data Flow

Introduction

Spring Cloud Data Flow (SCDF) is a cloud-native orchestration service for data microservices. It provides an easy way to create, deploy, and manage data pipelines. In this tutorial, we will explore how to use SCDF with Spring Boot to build a simple data processing application.

Prerequisites

Before starting, ensure you have the following installed:

Java Development Kit (JDK) 8 or higher
Apache Maven
Spring Boot
Spring Cloud Data Flow Server

Setting Up Spring Boot Application

First, we will create a new Spring Boot application. We will use Spring Initializr to bootstrap the project.

1. Generate Project

Go to Spring Initializr and set the following options:

Project: Maven Project
Language: Java
Spring Boot: 2.x.x
Dependencies: Spring Web, Spring Cloud Stream, Spring Cloud Data Flow

Click on "Generate" to download the project.

2. Import Project

Extract the downloaded zip file and import the project into your IDE (e.g., IntelliJ IDEA, Eclipse).

Configuring Application Properties

Open src/main/resources/application.yml and configure the application properties for Spring Cloud Data Flow.

application.yml

spring:
  cloud:
    stream:
      bindings:
        input:
          destination: input-topic
          group: group1
        output:
          destination: output-topic

Creating a Simple Stream Processor

We will create a simple stream processor that consumes messages from an input topic, processes them, and sends them to an output topic.

1. Create a Processor Class

Create a new class named MessageProcessor in the src/main/java/com/example/demo package:

import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.stereotype.Component;

@Component
@EnableBinding(Processor.class)
public class MessageProcessor {

    @StreamListener(Processor.INPUT)
    @SendTo(Processor.OUTPUT)
    public String process(String message) {
        return "Processed: " + message;
    }
}

Running Spring Cloud Data Flow

To run SCDF, you need to download and run the SCDF server. You can find the server on the Spring Cloud Data Flow website.

1. Start SCDF Server

Run the following command in your terminal:

./mvnw spring-boot:run

Deploying Your Application

Once the SCDF server is running, you can deploy your application by creating a stream definition. Open the SCDF dashboard in your browser at http://localhost:9393.

1. Create Stream

In the SCDF dashboard, create a new stream with the following definition:

stream create --name myStream --definition "myProcessor --input=input-topic --output=output-topic" --deploy

Testing the Application

You can test your application by sending messages to the input topic. You may use tools like curl or Postman to send messages.

1. Send Test Message

Use the following command to send a test message:

curl -X POST -H "Content-Type: application/json" -d '{"message": "Hello, World!"}' http://localhost:8080/input

Expected Output:

Processed: Hello, World!

Conclusion

In this tutorial, we covered how to set up a Spring Boot application integrated with Spring Cloud Data Flow. We created a simple stream processor that processes messages from an input topic and sends them to an output topic. SCDF allows you to manage your data pipelines effectively, making it a powerful tool for data processing in microservices architecture.

Spring Cloud Data Flow with Spring Boot Tutorial