a simple web based chat application built with Kotlin, Vaadin, Spring Boot and Apache Kafka

Intro In this post I show how to combine some language / frameworks and libraries / tools to build a web-based scalable chat application. I chose the following combination of tools: Kotlin as implementation language Vaadin for the web-based application Apache Kafka as the message backend Spring-Boot to get all together and running As I am bad in creating cool names for projects I just put together the first letters of the used tools and named this whole thing kovasbak.

Using Server-Push in a Vaadin app

Just a short post to show how easy it is with Vaadin 7 to use server push in an application. When doing some tasks in a background thread in a Vaadin application, there probably will come the time when some data needs to be shown in the UI. But as these data changes come from background processing, there is no direct possibility to show them in the UI, as UI changes normally are only reflected after a communication roundtrip from client to server to client which happens as a reaction to some user interaction.

Custom theme for a Vaadin & Spring-boot application

Recently I wrote an application based on Vaadin Spring-boot, and when I needed to modify the theme of the application I needed to do some research as how to achieve that. I think that at the time the combination of Vaadin and Spring-boot is still pretty new so that information still must be sought. So in this post I describe the necessary steps. I use the following versions of different tools: