Lightbend Activator

Reactive Stocks with Vaadin

Reactive Stocks with Vaadin

March 21, 2014
akka vaadin java java8

An example setup how one can create a RIA UI in plain Java to Akka actor system. Project uses some new Java 8 features, inluding lambda optimized API from Akka 2.3, but it can relatively easily be modified for Java 7 as well.

How to get "Reactive Stocks with Vaadin" on your computer

There are several ways to get this template.

Option 1: Choose vaadin-in-akka in the Lightbend Activator UI.

Already have Lightbend Activator (get it here)? Launch the UI then search for vaadin-in-akka in the list of templates.

Option 2: Download the vaadin-in-akka project as a zip archive

If you haven't installed Activator, you can get the code by downloading the template bundle for vaadin-in-akka.

  1. Download the Template Bundle for "Reactive Stocks with Vaadin"
  2. Extract the downloaded zip file to your system
  3. The bundle includes a small bootstrap script that can start Activator. To start Lightbend Activator's UI:

    In your File Explorer, navigate into the directory that the template was extracted to, right-click on the file named "activator.bat", then select "Open", and if prompted with a warning, click to continue:

    Or from a command line:

     C:\Users\typesafe\vaadin-in-akka> activator ui 
    This will start Lightbend Activator and open this template in your browser.

Option 3: Create a vaadin-in-akka project from the command line

If you have Lightbend Activator, use its command line mode to create a new project from this template. Type activator new PROJECTNAME vaadin-in-akka on the command line.

Option 4: View the template source

The creator of this template maintains it at

Option 5: Preview the tutorial below

We've included the text of this template's tutorial below, but it may work better if you view it inside Activator on your computer. Activator tutorials are often designed to be interactive.

Preview the tutorial

Explore the Code

Once the application has been compiled and the server started, your application can be accessed at: http://localhost:8080/. The compilation takes a while as the build does a full GWT compilation for the client side engine. Check in Run to see the server status.

You've just created a version of the iconic Reactive Stocks Akka example. Two big differences to the original project are that this version is build with Java 8 only and the UI is also built with Java only - with Vaadin. With Vaadin the UI development simplifies radically as developer can as developers don't need to think about browser, communication, html or such at all. Still, behind the scenes, Vaadin uses modern WebSocket communication to quickly show updates on UI.

Let's look at the src/main/java/com/vaadin/vaadininmuija/akka/ file. Here you will see the new lambda optimized Actor implementation.

Vaadin integration

Vaadin integration start from starting the actor system. This example runs as web application, thus the Servlet is a natural place to start the base system. It also holds reference to system and stocks hub.

StockUI contains the actual UI code: it is mostly basic Vaadin code to set up some components and adding them to layouts. In init method it also creates a special UIActor that will mediate the stock data from the actor system to Vaadin UI. Checkboxes send messages to stocks hub that which stock symbols UIActor should follow.

The purpose of UIActor is to mediate messages into Vaadin UI instance. This is the only Actor in this example system that knows something about Vaadin. In modular system you might want split that, Servlet and the actual UI code into a separate module.

Next Steps

You're now ready to really start learning how to write scalable and thread safe applications using Akka and Vaadin! While this tutorial you can get the basic integration example running, you'll probably still need more skills for either Akka or Vaadin, or possibly both. Activator itself contains several cool Akka examples. For more information about Vaadin, the Book is the definitive source. Also other parts of, like our helpful forum, may become useful.