A web application with Play, ScalaJS and ReactJS

As some of you may have noticed, we are setting up a seminar center in southern Spain where we will also host technical trainings. Our own focus these days is on the Scala language and the evolving Scala ecosystem, so it seems quite natural that we give Scala a try for the web site of our seminar house. Having heard about ScalaJS at Scala Exchange in December, I want to build the web application with Play on the Server side and ScalaJS / React on the client side. Today I’ll start a series of Blog entries describing the development of the application hoping it might proof useful for others trying something similar.

Having been a backend developer for most of my career so far I have limited experience with developing Web applications both on the client and the server side. Having a certain time limit I spent some time looking for applications of the shelf that would allow me to plan seminars and at the same time create a seminar calendar and maintain ongoing bookings - all integrated with the top nodge social networks. In about 6 weeks I have found nothing that I really liked. Either it was a small solution just to be used in the back office or it was too expensive for a small business like ours.

In the end I wondered what a technology stack would look like if I was to create the application myself from scratch and came up with Scala, Play, ScalaJS, ReactJS and MongoDB for persistence. Having heard about hosting platforms for Play applications I decided I wanted my application on Heroku with an attached MongoDB instance and also logging and monitoring plugins.

Note : I have chosen and these particular list of add-ons as they have free plans throughout the development cycle and promise to grow on demand as the application matures.


There is a ton of references and examples out there on building these kind of applications, but personally I found reading up on the entire range of topics proofed quite challenging. Therefore I have decided to capture my findings and the articles / books I have found useful in this blog series.

These are the ones I have started with:

Product and Tool documentation

Scala JS tutorial

This is a general introduction to ScalaJS and walks through the setup of simple, pure ScalaJS projects.

Hands-On ScalaJS

An online book on ScalaJS with more complex examples. All examples are included in the online book itself. Most interesting after going through the ScalaJS basics is the chapter on cross building Scala code for execution within a JS environment or a JVM.

ScalaJS/ReactJS examples

This is the homepage for scala-js/react completely built with scala-js/react itself. Most if not all of the examples of the original ReactJS tutorial can be found here in ScalaJS.

Play for Scala

Author   Peter Hilton
    Erik Bakker
    Francisco Canedo
ISBN   978-1-61729-079-4
Published By   Manning, 2014

Play Framework essentials

Author   Julien Richard-Foy
ISBN   978-1-78398-240-0
Published By   Packt Publishing, 2014

Extending Bootstrap

Author   Christoffer Niska
ISBN   978-1-78216-841-6
Published By   Packt Publishing, 2014


As stated above the application under development shall help me to manage seminars, bookings and my interactions with participants. In general it should make my life easier and let me concentrate on the fun parts like writing software. As some of the web technology is rather new for me I have decided to approach the application in explorative sprints. Each of the first couple of sprints shall familiarize myself with a yet unknown technology or component in the context of the overall project.

From today’s perspective the sprints should be :

Initial setup

In the first step I am going to create a minimalistic Play application and configure it for deployment on Heroku. Further I will go through the applications configuration with respect to monitoring and logging and attach the MongoDB instance to the application. The only change from a coding perspective will be that the project will already be tailored towards a multi-module SBT project.

The first Business Domain Object

In this sprint I will create a Scala case class for one of our business domain objects and explore how it can be used on the client and the server side. On the server I will implement a simple REST interface to interact with the business domain object.

The first React Component

Building on the REST interface of the last sprint I will implement a minimalistic React component to interact with the server. This shall give me some insight how Scala code can be used within the client and the server modules.

Integrating Authentication and Authorization

The next step is to restrict access for some operations on the server to certain users. I will use this sprint to explore the authentication and authorization patterns for this kind of applications. I will also explore the integration of popular social networks as authentication sources.

Implementing persistence

The last explorative sprint is to implement the persistence layer on top of MongoDB. In this sprint I will incorporate the appropriate drivers into the application and give the business domain objects a real persistent home.

Completing the UI Design

Once I have the technical details out of the way I can concentrate on the UI design and create a responsive layout based on Bootstrap 3. This will also include the refactoring towards multi-language support as the final application must support at least English, German and Spanish.

Finishing touches

The sprints so far should have covered the technical challenges around building a web application in pure Scala. Now the implementation of the remaining business domain objects and the associated UI components should be more or less straight forward.