what we blog

Come be part of our team!

We are looking to expand our team with a full-time Backend Developer (all genders) with experience in databases and backends. Our office is located in Kreuzberg and unfortunately not wheelchair accessible.

While we are generally welcoming developers...

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Rust, WebAssembly & Web Workers for speed and profit

In a recent client project we had the chance to refactor an existing feature with Rust, WebAssembly & web workers. In an internal web application used by logistics teams in multiple countries, one essential feature is the generation of QR codes. They...

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Rust Lifetimes for the Uninitialised

Heard of Rust? Then you may have heard of "lifetimes". They are one of the languages hallmark features, but sometimes also one of the most cursed. This isn't necessary.

Lifetimes are a interesting subject: a lot of people seem to gain a day-to-day...

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Getting started with Rust on the command line

This post is intended for people with no previous knowledge in Rust. It assumes some knowledge about programming, but none about Rust.

Rust has come a long way in the recent 2 years, from a promising new language to a practical day-to-day tool. Indeed...

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The Path to Rust on the Web

Recently there has been quite a bit of talk about WebAssembly, a new format for code for the web. It is a compile target for languages like C and Rust that enables us to write, and run, code from these languages in our browser.

In the interest of...

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Setting up a Rust Development Environment

In this post we'll be discussing one way to set up your machine for Rust development. There are different ways, particularly related to the text editor, so feel free to skip what is irrelevant to you. We'll focus on:

  • Setting up Rust via Rustup...
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The Future With Futures

Recently there has been a lot of progress in the Rust language towards a robust asynchronous stack. In this article we'll take a look at what these things are, take a tour of what's available, play with some examples, and talk about how the pieces...

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What I Learned from Giving a Rust Training

Over the last three days, I've given my first full training on Rust to ensure there's now four people in Germany that can call themselves "trained Rust engineers". Thanks to everyone who attended and thanks to Linuxhotel for organising the training...

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Come work at asquera!

Asquera is looking for a full-time Senior Backend Developer (all gender) with interest in databases and backends to complete our inclusive team. Our office is located in Kreuzberg and unfortunately not wheelchair accessible.

Who we are

Asquera, that...

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TDD with Guard

Using Guard for TDD

In the Ruby community testing and in particular test-driven development (TDD) is a common practice. When writing a gem this is often one of the first steps to set up by picking a suitable test framework. Creating a gem via Bundler

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Writing a command line application in Elixir

During the last days I got the chance to spend a bit of time playing around with Elixir. Elixir is, compared to other languages still a very new one. It has a Ruby-like syntax and compiles to Erlang VM bytecode. It is available for all major Linux...

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Testing external APIs in Ruby

Writing web services or applications that consume APIs is a common part of web development. Be it either a web service that is developed internally or by using an existing API from a 3rd party.

When writing tests against an external API one can face...

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Getting git right

On the 27th November, after the last Mrgn of the year, I spent the afternoon at the Getting Git Right event organised by Atlassian (makers of JIRA, Confluence, Stash, Bitbuckets and some other developer tools we have used before at asquera) and Codecentric...

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Asquera on Eurucamp

August is here and with August, eurucamp. Our CEO Florian was involved in the organising team as in previous years and the Asquera team will be attending the conference.

eurucamp started in 2011 as a reject conference for EuRuKo. This year eurucamp...

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Properly using Elasticsearch Script Filters

Elasticsearch comes with a vast number of filters and queries for all sorts of things, including special strategies and combinations of those. In some rare cases though, these are not enough. For these cases, Elasticsearch ships with the script filter, allowing arbitrary scripts to run on a document to decide whether it should be filtered or not.

These come at a high cost and are impractical to run on larger datasets. However, given the right approach, this can be mitigated.

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Berlin/wroc_love.rb Bus, 2nd Edition

We are big fans of the wroc_love.rb, not only because the first edition fell together with the founding of this very company. It is a nice, very affordable conference with a very well-picked, software-focused program. Because Wrocław is so close to...

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systemtap and Ruby 2.1 (on Ubuntu)

I like dtrace. I also like Linux. And thats where the problems begin: there is no proper dtrace for Linux. However, systemtap exists. systemtap is compatible to dtrace probes, however, it comes with it's own scripting language.

For those who don't know what any of these are: both are tools to efficiently trace programs at runtime, with a very low overhead. To allow that, they use so-called "probes" compiled into the program. Your kernel is usually equipped with such probes and Ruby 2.0 or higher also comes with quite a few of them.

However, the whole process is a bit involved and I found no good explanation for the whole setup and the pitfalls. Read on for my attempt. I will use Ubuntu as an example system.

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Jan Schulte joins Asquera

This month, we welcome Jan Schulte to strengthen our backend development team at asquera.

Jan Schulte

Originally from a small village in NRW, Jan worked in Hamburg for 1,5 years. He started his developer life with the Microsoft toolchain (Windows, Visual Studio...

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Ernesto Miguez is an Asquera - dor

We are pleased to welcome @xemig to the team. Ernesto brings his polyglot skills with computers and humans to Asquera where he will be part of the backend team.

Ernesto speaks fluent spanish, english, dutch, french and some german. His list of programming...

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An elasticsearch development workflow with curl and bash

elasticsearch is not quite like other databases - this is unsurprising, because elasticsearch is actually an index server. Data storage is secondary and happens though attaching the input data to a special field for later retrieval (thats the _source) field. This has interesting implications to your workflow. For that reason, I'd like to present my workflow when developing elasticsearch indices.

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Vagrant on Mavericks


Since this post got a lot of attention last night (hey all of you upgraders!) I'll add a couple of things that I figured out since writing the post.

  • Please note that this post refers to VirtualBox 4.2. In the meantime 4.3 has been released...
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My mum is a bad example, yours too

Just by accident, a tweet hit a nerve today and made me finally write this blog post. Also, to not bore you to death, its a "how I got started with IT" kind of story in disguise.

Please stop using "my mom" as a stand-in of "computer-illiterate" (and generally a bit dull on the technical side) person in your talks (and anywhere else, for the record). You will lose me there. Not because its subtly sexist (it is, for as long as "your dad" is not mentioned quite as often in that context), its also a subtle mistake. This might sound a bit like arguing semantics here, but let me explain on how its really an issue of not opposing your audience, because some of your audience does not hold your world view.

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Decoupled first

In Frontend first, Andrzej Krzywda argues for developing Frontends without any backend interaction first to make sure that all the user flow works and where and what you actually need to persist. I'd like to present a similar approach, but on another level.

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ElasticSearch pre-flight checklist

I attended the ElasticSearch base training this week and took away lots of very interesting details. I can definitely recommend taking them, the training made a lot of things clearer to me. One of my most immediate benefits was that it allowed me to compile a little "pre-flight" checklist of things that should never be skipped when bringing an ElasticSearch cluster to production. To ensure that I don't forget it and you don't start into your ElasticSearch life with huge amounts of pain, I'll document it here. Thanks to bascht for proofreading and fixes!

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Getting bored of the Rails Monotheism

Every once in a while, this tiny quote pops up in my twitter feed. I am not even sure where it originated.

This time, it ended in this conversation with Steve Klabnik.

As someone who has seen and implemented several successful and clean projects using Sinatra and subsequently Padrino, I'd like to call anyone out who uses this or any similar quotes to easily and try to explain both projects from my point of view. It basically comes down to a point of misunderstanding of what both projects try to accomplish. It might also be some miscommunication in the community as a whole. And the biggest point is a community that dukes out things like this on Twitter using 140 character quotes.

Sorry if things might become a bit inconsistent, I am basically writing a few things off my chest that nagged me for a while. I'll start by explaining where I see both Sinatra and Padrino in the webframework ecosystem.

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Hip but flawed: CFPs on Github

CFPs as pull requests on Github are the new hotness in town, at least when organizing a Ruby conference. Euruko 2012 did it, Sapporo RubyKaigi did it and RubyConf Australia and RuPy are following suit. My tweet today that I don't like the approach at all was met by a fair amount of reactions and I was asked to elaborate, so I'd like to do this here. I organized eurucamp this year and we consciously decided against it for various reasons, but these reasons are solely my own.

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Category: Open Source

Open source is the third category we'd like foster in this blog. We use a lot of open source and we write some as well. In this category, we'd like to talk about libraries we've found an like, changes to our own and things we learned in the process...

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The beginners track

The beginners track is another category that we want to turn into a regular one on this blog. Helping beginners is my hobby (granted, sometimes it pays the bills, too) and I still see a lack of high-level resources about programming techniques. While...

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Ruby tricks: introduction

Its one of our hobbies and thats why it became launch categories as well: weird ruby tricks. This category will show small ruby tricks that allows you to take a glimpse at how the language works. Some of them are useful, some are not, but usually fun...

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Ruby tricks: detect evaluation of default arguments

Default arguments are an often used feature of the Ruby programming language. Their basic syntax is simple:

def foo(bar = nil)
  bar == nil

This gives us two ways to make sure that foo evaluates to true:

a = nil
foo #=> true
foo("a") #=> false
foo(a) #=> true

Curious as we are, there is one question left: How do we detect whether the caller passed no argument or that he passed an argument, which just happened to be nil?

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Ruby tricks: in need of rescue

Throwing exceptions is nice, but handling them can get a bit of a chore. One of the main reasons: constant reindenting of your code because you insert or remove a begin end section. While your text editor should be able to cope with that just fine, reindenting is just a mess in source control. But, for trivial cases, we can call Ruby to the rescue!

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