Node Kafka simple example

NodeJS ecommerce proof of concept example using Apache Kafka.

Application flow

1. A new order is created.
2. The fraud detector do a verification to prevent payment frauds, it take some time to complete.
3. An email is sent to buyer informing if the order was accepted or rejected by fraud detector.
4. All messages are recived by log service.

NOTE: none of services above do a real job, is just a couple console.log's.

Kafka

In this project, are two topics ECOMMERCE_NEW_ORDER and ECOMMERCE_SEND_EMAIL. To add more topics add a new value to KAFKA_CREATE_TOPICS in docker-compose.yml separed by comma, the topic follow the NAME:PARTITIONS:REPLICAS:CLEANUP_POLICY pattern.

The messages are serialized in JSON format.

More configurations are available here.

The communication between NodeJS and Kafka is provided by kafkaJS.

Runinng

To run Kafka and Zookeeper run:

export HOST_IP=$(ifconfig | grep -E "([0-9]{1,3}\.){3}[0-9]{1,3}" | grep -v 127.0.0.1 | awk '{ print $2 }' | cut -f2 -d: | head -n1)
docker-compose up

Then, execute one service in each terminal

npm run log
npm run email
npm run fraud

To make an Order run:

npm run order

To change the fraud detection processing time create a .env file at project root folder, and add a FRAUD DETECTION TIME key in milliseconds, the default value is 2000ms (2 seconds).