This Gradle module hosts your web application and is able to build a WAR file which you can run in your favourite Servlet container.
Let's look at all files that this project is composed of, and what are the points where you'll add functionality:
| Files | Meaning |
|---|---|
| build.gradle.kts | Gradle build tool configuration files. Gradle is used to compile your app, download all dependency jars and build a war file |
| src/main/resources/ | A bunch of static files not compiled by Kotlin in any way; see below for explanation. |
| logback.xml | We're using Slf4j for logging and this is the configuration file for Slf4j |
| db/migration/ | Database upgrade instructions for the Flyway framework. Database is upgraded on every server boot, to ensure it's always up-to-date. See the Migration Naming Guide for more details. |
| webapp/ | static files provided as-is to the browser. See below for explanation |
| webapp/VAADIN/themes/ | The SCSS theme files applied to your web app. Vaadin by default uses the Vaadin Valo Theme; you can tweak the Valo theme by the means of setting the SCSS variables. |
| webapp/VAADIN/widgetsets/ | Vaadin components contains parts that run on the browser; since Vaadin components are developed in Java, GWT is used to compile the client-side part to JavaScript. This directory hosts the javascript produced by GWT; without it Vaadin app won't work. However, since we're not using any customized components, we'll just use vaadin-client-compiled.jar which already contains the Vaadin core components pre-compiled. |
| src/main/kotlin/ | The main Kotlin sources of your web app. You'll be mostly editing files located in this folder. |
| Bootstrap.kt | When Servlet Container (such as Tomcat) starts your app, it will run the Bootstrap.contextInitialized() function before any calls to your app are made. We need to bootstrap the Vaadin-on-Kotlin framework, in order to have support for the database; then we'll run Flyway migration scripts, to make sure that the database is up-to-date. After that's done, your app is ready to be serving client browsers. |
| MyUI.kt | The main UI of the app; typically contains a template UI code which guarantees unified look-and-feel of your app. You then typically provide a layout which will host the views as the user navigates througout the app. |
| WelcomeView.kt | The view, shown when the user browses the root page. Contains a happy picture of Chuck Norris. |
| Utils.kt | Utility stuff - a simple yes-no dialog which may come handly. |