ddovgal/geospatial-messenger

Geospatial messenger application written with Spring Boot + Kotlin + PostgreSQL

This is a sample application that demonstrates how to build a Kotlin + Spring Boot applications with a PostgreSQL database. The code is very concise, and the generated application is a 18 MBytes self-contained executable jar with low memory consumption.

A detailed blog post describing this application is available here.

It is used as a playground to demonstrate various features:

• Gradle build.gradle.kts file written in Kotlin instead of Groovy, see gradle-script-kotlin for more details.
• Simple User and Message domain model classes thanks to Kotlin data classes.
• The Application class shows how to configure a Kotlin Spring Boot application.
• Typesafe SQL DSL with Exposed that allows to define your SQL tables and describe your SQL requests with a fluent API without requiring code generation.
• Controllers demonstrates how to use Spring Framework 4.3 upcoming @GetMapping and @PostMapping annotation shortcuts, as well as Server-Sent Events to push data to the client.
• Kotlin extensions allows to add Geospatial support to Exposed and use it as if this was supported out of the box.
• The REST API is fully tested and documented thanks to the awesome Spring REST docs , see MessageControllerTests and index.adoc.
• The client side is originally a pure HTML + Javascript application developed with OpenLayers mapping library, see index.html and map.js. But an experimental (work in progress) Kotlin2js version has ben contributed by @bashor, you can find it here.

A Spring Data version based on spring-data-jdbc-repository is also available in this branch. There is no Spring Data JPA version yet but feel free to fork this repo and contribute it with a pull request!

Run the application

• Install a PostgreSQL database with PostGis extension, on Mac you can use Postgresapp.
• Clone this repository.
• Customize database configuration on application.yml.
• Run it within your IDE or with ./gradlew bootRun.
• Open http://localhost:8080/ in your browser.
• Documentation should be available at http://localhost:8080/docs/index.html when run from the JAR.

Improvements I have in mind

• Exposed issue #24: see if Exposed could support natively data classes + repository patten.
• Spring HATEOAS issue #401: add HATEOAS support, but without having to extend ResourceSupport or wrapping it into a Resource<Foo> container .
• Kotlin issue KT-11235: avoid mandatory usage of arrayOf in annotation array attribute (for example in @SpringApplicationConfiguration(classes = arrayOf(Application::class)).