Open Source Ecosystems

Kotlin Reactive Micro Services Example

IntelliJ code coverage runner gives a 100%, unfortunately I've not managed to get the same results using codecov.io and JaCoCo

info

This is an example of doing reactive MicroServices using spring 5 functional web framework and spring boot 2 using Kotlin.

This is a fork of the original java version.

This service provide and API that will get the geo location and the sunrise and sunset times from an address.

Scenario: Get Location
  Given I've an address
  When I call the location service
  Then I should get a geo location
  And I should get the sunrise and sunset times

To implement this example we consume a couple of REST APIs.

This example cover several topics:

Functional programing.
Reactive types.
Router Functions.
Static Web-Content.
Creation on Reactive Java Services/Components.
Error handling in routes and services.
Reactive Web Client to consume external REST Services.
Organizing your project in manageable packaging.

Includes and in depth look to testing using JUnit5:

Unit, Integration and System tests.
Mocking, including reactive functions and JSON responses.
BDD style assertions.
Test tags with maven profiles.

Sample requests

Get from address

$ curl -X GET "http://localhost:8080/api/location/Trafalgar%20Square%2C%20London%2C%20England" -H  "accept: application/json"

Post from JSON

$ curl -X POST "http://localhost:8080/api/location" -H  "accept: application/json" -H  "content-type: application/json" -d "{  \"address\": \"Trafalgar Square, London, England\"}"

Both will produce something like:

{
  "geographicCoordinates": {
    "latitude": 51.508039,
    "longitude": -0.128069
  },
  "sunriseSunset": {
    "sunrise": "2017-05-21T03:59:08+00:00",
    "sunset": "2017-05-21T19:55:11+00:00"
  }
}

All date and times are ISO 8601 UTC without summer time adjustment

API

Project Structure

main/kotlin
- /application : Main Spring boot application and context configuration.
- /extensions : Custom kotlin extensions and high level functions.
- /routers : Reactive routing functions.
- /handlers : Handlers used by the routers.
- /services : Services for the business logic needed by handlers.
- /exceptions : Businesses exceptions.
- /model : Data classes.
test/kotlin
- /application : Application system and unit tests.
- /extensions : Extensions unit tests.
- /routers : Integration tests for routes.
- /handlers : Unit tests for handlers.
- /services : Unit tests for services.
- /test : Helpers and base classes for testing.