Tuesday, May 22, 2018

A new challenge

It has been quiet on my blog for a while, but don't worry, I'm still alive. In my absence, many things have happened. Most importantly, I have decided to embark on a new challenge.

Almost two months ago, I joined Mendix, a Rotterdam-based company (with its headquarters located in Boston) that ships a low-code application development platform. I will be working on their deployment infrastructure and I will be thinking about software modularity.

Some reflection

I vividly remember the days when I completed my PhD and left academia -- I still had to wait a couple of months for the defence ceremony, mainly because of the availability of the committee members.

Although I was quite happy with some of the work I had done during my research, I also wanted to leave my ivory tower and be more connected to the "real world" and my "research audience": developers. I joined a small startup company named Conference Compass (located in the YES!Delft incubator centre) that consisted of fewer than 10 people around the time I joined.

They had been looking into a setting up a product-line for their mobile conference apps, which sounded like an interesting challenge.

In the years that I was employed at Conference Compass, quite a few things happened. Most notably, the size of the company, the product and the service portfolio have grown considerably. Aside from these developments, I am particularly proud that I made quite a number of impacting open source contributions as part of my daily work.

The app building infrastructure

The biggest contribution I made by far is the mobile app building infrastructure. Most of its components have been part of Nixpkgs (the ecosystem of packages that can be deployed with the Nix package manager) for several years, such as:

To carry out all the builds on a large and timely scale, I installed a Hydra cluster: a Nix-based continuous integration service. I also developed an NPM module and command-line tool that we could use to remotely control a Hydra server from our custom built applications.

Chat functionality

Another interesting development area was enriching the app's product line with chat functionality built around the XMPP protocol/ejabberd service. I have ported the Simple XMPP library from the Node.js package ecosystem to Titanium by using a zero-forking strategy and I made a simple test application that somewhat resembles the Pidgin chat application.

I also ran into a number of practical issues while trying to keep the architecture of the test app clean. I did an in-depth study on the MVC paradigm and wrote a blog post about my findings.


I also learned quite a lot about Node.js and its underlying concepts, such as asynchronous programming. Before joining Conference Compass, my JavaScript knowledge was limited to browser usage only, and I was not using JavaScript on a very extensive scale.

My learning experiences resulted in the following blog posts elaborating about various kinds of related concepts:

As of today, some of these blog posts are still in my all-time top 10 of most frequently read blog posts.

As a result of having to work with Node.js and being involved with the Nix project, I became the maintainer of node2nix, a tool that can generate Nix expressions from NPM package configurations after the maintainer of npm2nix decided to hand over the project.

Building a service deployment platform

In the first two years of my employment, my chief responsibility was the app building infrastructure. Another thing I am particularly proud of is the deployment infrastructure for the service platform that I built from scratch, that grew from just a single virtual machine hosted in the Amazon EC2 cloud to a platform managing the data and configuration services for 100+ apps per year, with some events attracting tens of thousands of app users.

I used variety of solutions, such as various Amazon web services, e.g. EC2, Route 53, S3. Most importantly, I used NixOps for infrastructure deployment and Disnix (the tool I created as part of my research) for service deployment.

Although Disnix already supported all the features I needed before I actually started using it at Conference Compass, my company experiences helped to substantially improve Disnix from a usability perspective -- in academia, Disnix was mostly used to validate my research objectives. To make it suitable for using it in a company with non-specialized deployment people, you need iron out many additional issues. I added more helpful error messages, assistance in recovering from errors and additional utilities to make diagnosing problems and carrying out maintenance tasks more convenient.

At the end of 2015, after using Disnix for almost one year in production, I gave a talk about Disnix's deployment concepts at NixCon 2015, the first edition of a conference fully centered around Nix and its related technologies.


I am grateful to my previous employer: Conference Compass who gave me the opportunity to do all the things described in this blog post.

At Mendix, there will be many new interesting challenges for me -- I will be working with different kinds of technologies, a new platform and new people. Stay tuned, for more information...

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