Devoxx 2012

This week is the Java week of the year, Devoxx time. I has been trending on twitter since monday, but I’m only going the first 2 conference days, so tomorrow is the big day.
Last year the keynotes (by oracle) were very boring and Stephan promised some better ones this year. It looks like he succeeded. After the keynotes I’m going to focus
on the Future track. This is a new track and looks like a lot of fun. Last year I devoted most of my Devoxx schedule to Scala and I would the same this this year, but there aren’t that many Scala talks (except on the university days). But still I’m going to watch innovative talks about topics that just sound appealing, avoiding partner slots and boring jre spec lectures.
Every year I also pick some talks just based on the speakers, since a good speaker mostly means a good talk.
So this is my programme

  • Wednesday
    • Keynotes
    • The secrest of the Square Stack
    • Home automation for geeks
    • Do you like coffee with your dessert? Java and the raspberry Pi or Fork/Join (doubting since the fork/join and lambda talks aren’t very appeling to me)
    • Effective Scala
  • Thursday
    • Keynotes
    • How to build big data pipelines for Hadoop using OSS
    • OAuth 2 and Identity
    • Simplicity in Scala design (will have to skip Akka talk :( )
    • JavaPosse LIVE (du’h)
    • Re-imagining the browser with angularjs

If you see me, come say hi!

Understanding foldLeft in scala

As I’m working on some scala code the last few weeks, i have come across some functions in the scala api that I didn’t understand right away. One of those functions was foldLeft, FoldLeft is a relative easy method, but the scaladoc is not quite clear.

Applies a binary operator to a start value and all elements of this list, going left to right.

What the method actually does is apply a method on all the elements of a Sequence and accumulating it a variable. The initial value of that variable is give as first parameter, the second parameter is the function you apply.
In java it would like this

T accumulator = initialValue;
for(X listItem : list){
    accumulator = method(accumulator, listItem);
return accumulator;

Take is an integer and method does “accumulator + listItem”, we get a method that adds all integers with eachother starting from the initial value.

val list = List(1,2,3)
list.foldLeft(0)(_ + _)

The first parameter of the function given as argument is the accumulator, the second is the current value (or listItem in the java example). foldLeft results in 6.

First steps into Scala

For over a full year now, I’ve been looking into Scala. I have heard many people talk about it passionately and it just got me interested. Also a lot of big companies are investing in this new language. I just figured I had to check it out.
In my 4 years of Java programming, I’ve learned the Java EE stack, (Spring and Java EE) and I must say, not much has changed since then. We got the long awaited release of Java 7 (with lots of features missing) and in 2009 Sun released Java EE 6.
Java EE 6 was a cool release and I have blogged about it for a few times but it is not more than just more abstraction of the same concepts. Spring hasn’t really been moving forward at all. When you look at the release which was used when I started programming professionally and the one we use in production, it is largely still the same version. There is a 3.0 release but to be honest, it is not very compelling.
So after hearing people like Dick Wall talk about Scala for a long time, I decided to pick it up. The first thing I have tried was the Scala Koans.
Scala cones is a project on github that helps you to learn a language by correcting failing tests. At the time the Scala Koans project was still in the very early stage and I did not get them to work and gave up rather quickly.
My second attempt at Scala was when I had some spare time and I wrote a simple application which parsed some XML. This worked but in the end this only took me 5 minutes, looking back at it now, I did not use any language feature that was an added value. The only thing I did, was write Java in Scala.
In the mean time I joined the Belgian Scala Enthousiasts and I’m following the mailing list, but still, I couldn’t really write a true Scala application. I didn’t even get the feeling I was hitting it off.
At Devoxx 2011 I was determined to go and see the Scala talks and things that have to do with Scala. I ended up seeing 2 talks about the Play! framework, 3 talks about Scala and a talk about Akka. I did also talk to the guy’s at MongoDB and Typesafe.
Devoxx 2011 was a real eye opener for me to get started with Scala. There were many reasons, first of all there were the talks.

The talk about play! 2.0 showed me how to build a web application with Scala. It also demonstrated what a cool framework Play! is.
The Akka talk showed me how to create super scalable and decoupled applications. It is written in Scala and integrated with the play! framework (version2.0) which was a plus for me.

The talk from Matt Raible didn’t really show me something technical. His talk was about some technologies he wanted to learn (Scala, Play, Coffeescript, {Less}, scalate and jade). He wanted to talk on Devoxx so badly so he just submitted a talk. At the time when he submitted the talk he didn’t know any of the technologies he was going to talk about. He even waited to start learning them until his talk got accepted. Only after the approval, he started learning and blogging about these technologies and then showed what he built at Devoxx. His talk was about the same thing which I was trying to do for over a year, but never pushed through. It might sound corny, but this talk was the real boost for what I’m doing now.

On the other hand I had 2 interesting chats in the downstairs hall.

One was with a mongoDB guy. He showed me the API he had built for connecting with mongoDB from Scala. Unfortunately, I did not get his name… The other was with Henrik Engstr√∂m, a developer who works at Typesafe (A company founded by Martin Odersky, the creator of the Scala language and next to Scala they also house the play! framework and akka).

We just talked about how you can use scala in web applications.

When I got back from Devoxx, I literally got home and downloaded the Scala runtime, the Typesafe stack (at the time this was only Scala, Akka and the Scala IDE) and the beta of the Play! framework. I have a small project in my head that I’ve been thinking about for some time now and I started implementing it.

Based upon the 3 Scala examples with which the Play! 2.0 beta ships, I’m learning the language bit by bit. But there were a lot of language features I didn’t really grasp. I tried to look into the scala doc but got even more confused. I knew that Typesafe is offering a free book ‘Scala for the Impatient‘, so I decided to check it out. I downloaded that book and started reading it. Things cleared up immensely. I now understand why people say Scala isn’t complex, it just looks that way. Well it’s true. It also explains the weird things you see in the Scala API documentation.
Now I’m working with Play! 2.0 and Scala. When I’m getting the hang of it, I’ll also try integrating Akka and probably deploy it on Heroku¬†and see what it can do.
I’m going to try to keep documenting my steps into Scala, Play! and Akka. I’ll see where It takes me.

Bootstrap, from Twitter

On Devoxx 2011, about a month ago, I heard about this cool new concept, ‘Bootstrap from Twitter’. The idea is brilliant in its simplicity.
It targets developers of new applications. If you are playing around with a proof of concept, hacking away in some new programming language or just focussing on getting the something to work right, then this is just the thing for you.
The basic idea is that Twitter gave away some basic css and javascript for building web applications. That’s just it. Bootstrap just gives you the most common used styles and javascript that Twitter uses. You can download it, plug it into whatever you are building and get stared.
Currently I’m playing around with the beta release from play 2.0 (see what I did there). And now I’m building a text based app with ugly formatted forms etc. Everyone who has ever build something from scratch probably knows what I’m talking about. Just by adding the css (I use the less version of it since bootstrap is build with less from the start), I go from this

to this

Perhaps the difference is not very impressive but everything looks a bit more web 2.0. When we start to apply some basic css classes to our login form we can easily improve it more.

As you can see the botstrap css contains basic css for most, not to say all aplications. This way you can build a demo without having to worry that it looks slick.
Eventually I ended up with this, I won’t use it and I know it is a bit redundant, but I just wanted to show the potential lying in this cool project

Bootstrap also includes other features, a short summary

  • Example Layouts (based on the but without the 10px margins)
  • Basic Typography
  • Media grids
  • Table styles
  • Forms layout
  • Navigation styles
  • Styles for Alerts & Errors
  • Popovers (modal windows)

I know this is not the most technical topic to blog about, but I think that every developer sees the benifit of using this.
You can download Bootstrap here and check out the other features here or just go ahead and fork the project on github.

Devoxx 2011: A crash course in Scala

Devoxx time again, 4th year that I’m attending. This morning I went to see the talk by Mario Fusco and Kevin Wright. The first part was by Mario and handled the Scala basics. The talk itself was a bit messy. It was a mix of API features and a comparison with Java, Groovy and Haskell.
He showed some cool language features, but overall it was just an API features list, but the demo that was given was pretty cool. The demo showed how easily you could create a DSL with Scala.
In 2 minutes he was able to write something like this.

   3 times{

Eventually the code printed “hello” 6 times. It is a bit a trivial example, but really fun to see what the power is of scala.

The second part of the talk was about how Scala would be agile in a project. Kevin also emphasized on the way we can write code that is very readable for developers and for the business users. He started with an example that he apparently stole from Dick Wall :-). The example just showed how everything in Scala is manipulable.

A long time ago in a galaxy far far away

translated into


So these are just a class (A), a few methods (long, ago, a, far and away) and some vals (time, in, galaxy and again far).
This was quite nice and showed the potential to build readable code for the business users.
For a more powerful example he referenced to a gist he created on github, where a string of validation rules can easily be added to a processor and then return the result. (on top you have the method declarations, on line 44 you got the actual processor that is being defined and at the bottom you find some test with the result in comment).
Again, I heard that the best way to start with Scala is to write your tests in Scala. This code does not go into production so it does not create a risk, but the developers start playing with and learning Scala so they get a good feel about what is possible.
The most important thing I remember from this talk is that you can learn a fair amount of Scala in 2 weeks, but you’ll need more time to learn a specific business domain. By writing your business apps in readable Scala, you could lower the step to get into the business.
It was an interesting talk that showed possible usages of Scala in a real environment, but I’m not sure it convinced many people to start using Scala.