Sander van den Oever

Sander van den Oever
Computer Science student

Track: Software Technology
Interests: Software (Web) Engineering
Occupation: PHP Developer

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March 2016
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New courses and ING 24H-Coding

Hi all,

The third quarter brought me some new courses and other activities. New courses I am following are Software Architecture by Arie van Deursen and Software Re-engineering by Andy Zaidman. I’m also participating in the ING hackathon next week, which I’ll talk about in a bit.

Software Re-engineering

Let’s start with discussing Software Re-engineering a bit. This course focuses on the way we look at existing software systems. How do we deal with a large system that has been developed over the course of several years? How can one efficiently enhance the structure of such a project, while assuring that everything still works as it is supposed to work? We have learned about the S.O.L.I.D.-principles (which some of you might be familiar with already) and how to refactor violations of these principles. We have learned about testing, how to develop tests to tests your hypotheses, refactor, and test again. Our knowledge was tested on a real-life example. Together with the other students we had to identify violations of several principles and following on that deliverable we had to actually refactor these violations. The system that was used this year is jMonkeyEngine. jMonkeyEngine is a 3D game engine written in Java. We have used several tools like inCode, CodeCity and other tools like code coverage tools to find all kinds of flaws and violations.

CodeCity visualisation of jMonkeyEngine

Figure 1 – CodeCity visualisation of jMonkeyEngine

In the Figure 1 you can see a visual representation of jMonkeyEngine as build with CodeCity. CodeCity renders your code as a ‘city’ giving you a quick overview of the project. Packages are being transformed into districts, classes are transformed into buildings where the properties of a class determine the properties of these buildings. For instance, one can choose to use the #Lines of Code (LOC) metric for the height of a building and the number of methods metric for the width of the building. One can also use colours on the buildings, to indicate (for example) the number of external dependencies. Classes that have a lot of methods or classes that are being referenced a lot by other classes might be suffering from the God Class-violation. These classes would (if using the right metrics of course) be noticeable fairly easy (big skyscrapers).

Software Architecture

Software Architecture is a course taught by Arie van Deursen. He uses GitHub for all course material and Slack for communication and announcements. Within this course we had to pick an open-source, GitHub hosted, software system that has been active recently (e.g. approximately one pull-request per day minimum). We, my team and I, have decided to work on the youtube-dl project. Youtube-dl is a command-line tool that allows you to download video’s from over 700 (!) supported websites. Within this course we had to analyse this system (it’s internal structure) and write a report about our findings. Next to that, the fun part of this course in my opinion, we had to think of potential contributions to the project. The course actually required us to make some contributions. We had to contact the development team and try to get our contributions merged into the project. In many cases this involved rather simple documentation fixes, but there have been contributions that add or fix actual functionality as well. The course staff wanted us students to use Slack for all communication. This way students are able to help each other efficiently and the staff was able to keep track of the group process. Read more about this course and its setup in the blogpost by Arie van Deursen, which can be found on his website:

The reports of our findings we have to bundle within a chapter. From all teams (all delivering their chapters) a given number will be selected, bundled and published as the DESOSA 2016 book. An example of the previous edition of the course can be found at We are currently reviewing chapters written by other teams, while we are still trying to contribute to the youtube-dl project. Examples of (our) contributions are #8785,  #8682 and #8680. For our chapter we have created several architectural views, for example the one below, depicting the contextual view (stakeholders and other related tools/companies).

Context View

Figure 2 – Context View of youtube-dl.

ING 24H-Coding

Together with some friends I will participate in the ING 24H-Coding event in Amsterdam. Basically all kinds of teams participate here in building prototypes for their ideas and pitch them to ING. This years theme was about building a omnichannel software solution. Within that context we are free to think of anything we like. The event will be held in the Heineken Music Hall, where food and drinks are included, we only have to bring our laptops. There are not that many student teams participating so I’m really curious about the outcome of our team/idea.

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