Christian Semmler

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Building a mobile app using Flutter in two weeks (iOS + Android)

Nov 20, 2021
This summer, we decided to architect and implement a mobile app accommodating the e-learning platform of one of our clients, troodi. We have chosen the Flutter framework, which allowed us to rapidly build a production-grade app within two weeks, ready to be deployed on both the iOS and Google Play app stores.
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sidekiq_workflows: a workflows API on top of Sidekiq Pro

Sep 24, 2021
Sidekiq is one of the most popular background job processing systems in the Ruby ecosystem, which I’ve been using for almost a decade in at least half a dozen projects. The basic version is open-source and available under the LGPL license. A major feature introduced with Sidekiq Pro are batches - which I've written a gem for.
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How to set up a 24/7 live stream radio on YouTube (for free)

Nov 21, 2020
Have you ever come across a YouTube video that endlessly loops a playlist of music? This post outlines a way to launch such a live radio using ffmpeg, the swiss army knife when it comes to any kind of media streaming or transformation, and a simple Docker image. You can even host the entire setup for free on services like Heroku.
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Reflections on 10 years as a software engineer

Sep 3, 2020
10 years ago, I started working professionally as a software engineer. Now, in 2020, it's time to take a look back. In this post, which is more personal than technical, I'm exploring how I turned my hobby into a profession, including examples of both personal and commercial projects, and how my perspectives changed along the way.
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Fast JSON Schema validation in Ruby

Aug 30, 2018
Defining JSON APIs using JSON Schema is growing in popularity, and for good reason. A schema can help with validation, documentation, and type definition. When it becomes an integral part of your stack, it's important to make sure that validation in particular is performing well enough not to slow down your API.
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Why C++ (is fun to me): template metaprogramming

Jul 1, 2017
If you need to expose a number of functions in C++ to an interface, template metaprogramming may be of tremendous help. This post outlines one such case. Here is the entire working code example (GCC's optimizer is good enough to optimize all of the program away, that's why the compiled version is blank!)
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