Skip to main content

Second try with Scala and REST

As I mentioned in my previous post I tried to create a simple REST service with Scala and spray.io, but that turned out to be unbelievably difficult. A second try with Scala and REST turned out to be successful.

Play to the rescue


When my experiment with spray.io didn't work out I had an idea to try out Play 2 as a base to my REST service. Working with Play 2 was a walk in the park compared to spray.io even though not entirely painless but much easier and less frustrating.

Starting out with Play 2 was really quick thanks to a good documentation and examples that are up to date. Basically I just ran the command play new appName and started coding.

So far I have REST service and a in-memory implementation of todo tasks with some unit tests. REST service is all Play 2 with routes and a single application class. The current service layer implementation is a single class with tasks in a mutable Map where a individual task is a case class, so just some basic Scala code.

I really like Play 2 so far but I'm a bit concerned of how much dependencies Play 2 brings with it as default. Currently I have 92 jars in referenced libraries of my project, all from default initialization of play application. Sure some of these are test library dependencies but still that's a lot of libraries.

Unit testing Scala code


Play 2 automatically includes as a dependency the specs2 library that's a unit and acceptance testing library for Scala. I had never used specs2 and the bdd style definition of tests was a bit odd to me but I decided to give it a try.

After a few initial wtf's I got the hang of it pretty quickly and was able create some basic unit tests for my service implementation. I've only scratched the surface with specs2 but it seems to do the job and has quick learning curve and so far the provided documentation has been enough to get me going.

What's next


Next step in my adventures in the world of Scala will be to try use some real data storage to persist the todo applications data. I think I'll try out with MongoDB and after that some other very different alternatives like Redis and MariaDB. 


Code shared publicly


As I use code and examples provided by others I too am sharing my code and putting it publicly reviewed by others. It's all shared through my github account at https://github.com/jorilytter/simple-todo, feel free take a look.

Popular posts from this blog

Simple code: Naming things

There are two hard things in programming and naming is one them. If you don't believe me ask Martin Fowler https://www.martinfowler.com/bliki/TwoHardThings.html . In this post I'll be covering some general conventions for naming things to improve readability and understandabilty of the code. There are lots of things that need a name in programming. Starting from higher abstractions to lower we need to name a project, API or library, we probably need to name the source code repository, when we get to the code we need to name our modules or packages, we give names to classes, objects, interfaces and in those we name our functions or methods and within those we name our variables. Overall a lot of things to name. TLDR; Basic rule There's a single basic convention to follow to achiveve better, more descriptive naming of things. Give it a meaningful name i.e. don't use shorthands like gen or single letter variables like a, x, z instead tell what it represents, what it does...

DIY home automation, new generation

I've had my DIY home automation system for controlling outlets and reading sensor data running for about two years now. The system has been working fine and I haven't had any need to touch the code since I added the sensor reading to it, until a few months back. Need for new functionality Few months ago I got a new IoT toy for a lend from a friend until I'd get my own toys, a ruuvitag sensor beacon. Ever since I found the ruuvitag for the first time from kickstarter I had the idea of getting a bunch of ruuvitags and adding their weather station sensor readings as part of my home automation system. The original home automation backend included only tellstick compatible devices and was written in Python, and in my mind it was kind of a hack. The ruuvitag beacons communicate via BLE i.e. Bluetooth Low Energy and that meant that I needed to add functionality to read the beacon data via bluetooth. I found a ruuvitag Python library and initially thought that I'd just...

Simple code: Unit tests

Unit tests are the developers number one safety net. Let that sink in. This is the number one reason for writing unit tests. Unit tests are written by developers for developers to ensure that the code works as expected and handles happy and sad paths correctly. With enough unit test coverage the tests enable a safe environment for refactoring and rewriting code. Unit test scope Unit test should test a single thing, a method or function call and it should test only one use case within. In other words a unit test should test a function with a single input. This is a important guideline to understand. When a unit test tests a function with single input it makes the test isolated, repeatable and predictable. Example of good tests: @Test fun findsAddress() {   val address = findAddress("Stevens street 35", "Southport", "Australia")   assertThat(address).isNotNull() } @Test fun doesNotFindAddress() {   val address = findAddress("Stevens street 697", ...