vertx-spring-boot-sample-kafka

Vert.x Kafka example

This example demonstrates a simple application with a Kafka publisher and a subscriber.

Application workflow

Log message

POST request > controller > logger > Kafka broker > log

Receiving logged messages

GET request > controller > log > controller > GET response

Usage

Start a Kafka cluster and configure its bootstrap URLs in src/main/resources/application.yml. It is done separately for producer and consumer. In this example application it is set to localhost:9092 by default.

Build the application.

mvn clean package

Start the application in one terminal window.

java -jar target/vertx-spring-boot-sample-kafka.jar 

And access it in another.

First submit a couple of messages for processing.

echo "Hello, World" | http POST :8080
echo "Hello again" | http POST :8080 

Then check the result.

http :8080

You should get something like the following.

HTTP/1.1 200 OK
Content-Type: text/event-stream;charset=UTF-8
transfer-encoding: chunked

data:Hello, World

data:Hello again

Kafka configuration

Kafka client configuration is very straightforward and is done via application.(yml|properties) file. Here's the one used in this application.

vertx:
  kafka:
    producer:
      bootstrap:
        # Default bootstrap servers to be used by producers        
        servers: localhost:9092
      key:
        # Default key serializer to be used by producers
        serializer: org.apache.kafka.common.serialization.StringSerializer
      value:
        # Default value serializer to be used by producers
        serializer: org.apache.kafka.common.serialization.StringSerializer
    consumer:
      bootstrap:
        # Default bootstrap servers to be used by consumers
        servers: localhost:9092
      group:
        # Default consumer group id
        id: log
      key:
        # Default key deserializer to be used by consumers
        deserializer: org.apache.kafka.common.serialization.StringDeserializer
      value:
        # Default value deserializer to be used by consumers
        deserializer: org.apache.kafka.common.serialization.StringDeserializer

You can set any standard Kafka property by using vertx.kafka.producer or vertx.kafka.consumer prefixes for producer and consumer respectively.