Simple Asynchronous Microservice Communication Example with Event-Driven Architecture

Demo project for Microservice Event-Driven Architecture

• Kotlin & Java
• Spring Boot Web
• Spring Cloud Stream Kafka

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Requirements

1. Java - 1.11.x
2. Gradle- 3.x.x
3. Docker for kafka instance

Service Name	Port
Order Service	8083
Courier Service	8084
Email Service	8085

Step 1: Running the Kafka & Zookeeper Open the project directory, Type the following command in your terminal to run kafka&zookeeper as a docker instances

 docker-compose up -d

Step 2: Running the Order Service Open the this project path then order-service directory. Run the project with gradle:

 ./gradlew bootRun

Step 3: Running the Courier Service Open the this project path then courier-service directory. Run the project with gradle:

 ./gradlew bootRun

Step 4: Running the Courier Service Open the this project path then email-service directory. Run the project with gradle:

 ./gradlew bootRun

Rest APIs

The app defines following for APIs.

POST http://localhost:8083/orders

{
    "name": "Black Friday",
    "productIds": [
        14,
        23,
        34
    ],
    "email": "gokhana@mail.com",
    "userName": "G-khan",
    "orderDetail": "%90 discount"
}

Example

These examples present the order created event flow.

• Order Creates with API
• Order Service Creates Event as a OrderEvent with Created eventType
• Order Service produces orderEvent via kafka on orderEvent topic.
• Courier Service consumes the orderEvent and then assign the courier of order
• At the same time Email Service consumes the OrderEvent and then sends a fake email to user