Reactive Micro Services Example

info

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

There is a Kotlin fork of this service.

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.

usage

To run this service:

$ mvnw spring-boot:run

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

View in the embedded Swagger UI

Run in Postman

Project Structure

• main/java
  • /application : Main Spring boot application and context configuration.
  • /routers : Reactive routing functions.
  • /handlers : Handlers used by the routers.
  • /services : Services for the business logic needed by handlers.
  • /exceptions : Businesses exceptions.
  • /model : POJOs.
• test/java
  • /application : Application system and unit tests.
  • /routers : Integration tests for routes.
  • /handlers : Unit tests for handlers.
  • /services : Unit tests for services.
  • /model : POJOs used by the test.
  • /test : Helpers and base classes for testing.

References

• https://spring.io/blog/2016/09/22/new-in-spring-5-functional-web-framework
• https://spring.io/blog/2017/02/23/spring-framework-5-0-m5-update
• http://junit.org/junit5/docs/current/user-guide/#running-tests-build-maven
• https://github.com/junit-team/junit5-samples
• https://developers.google.com/maps/documentation/geocoding/intro
• https://sunrise-sunset.org/api
• https://en.wikipedia.org/wiki/ISO_8601