Babbel Bytes

Insights from the Babbel engineering team

Retrofit 2 and Rx Java call adapter error handling

Frederico Gonçalves

If you’ve kept yourself up to date with the latest in Retrofit you’ve soon came to the question “Should I or shouldn’t I update to Retrofit 2?”. At Babbel we’ve already answered the question, we updated our new Android app to use Retrofit 2.

Although still in a beta stage, Retrofit 2 already offers a lot. However, there are some crucial changes. Perhaps one of the changes that affected us the most was the removal of RetrofitError. There are more than one reason why this class was removed, but we weren’t ready to give up on it so fast. As an intermediate step we needed to port its behavior to Retrofit 2 while using RxJava.

The new Retrofit design helps you define call adapters that can help you customize how you handle errors in your calls.


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Babbel 4th Hackday - our review

Giulia

Twice a year we break out of our everyday routine and meet somewhere in Berlin to form ad hoc teams working on our own project ideas and hacks. Some of them eventually become actual Babbel projects.

As the Babbel family is growing pretty fast lately – and so is the list of the Hackday attendants – the venue research can get really hard; this time we had an exciting option, though…our future office!

A completely empty 5–storey building close to Alexanderplatz just for us and during the Halloween weekend. Creepy!? Scary!? Exciting!

We took over its big empty open space and we brought tables, chairs, sofas, bin bags, lights, super Wifi, coffee, snacks, Club Mates, beers…and last but not least, 110 Babbel – Hackers; 110 people from Product, Engineering, Data Analytics, Marketing, Customer Support, Design, Didactics, Internal Communication worked from 10 am to 19.30 pm on 26 different projects.

4th Babbel Hackday


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How we upgraded a big Ruby on Rails monolith with Zero Downtime

Sebastian

In September 2015, we started taking the Rails upgrade of our monolith seriously. We were running Rails 3.2 up to that point, and with Rails 5 on its way, we ran into the risk of using an unmaintained version of the web framework. This was not an option. Hence, the upgrade to a current Rails 4 version was inevitable.


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Evolution of Babbel’s data pipeline on AWS: from SQS to Kinesis

Kirill Shirinkin

Various data storages have seen increased growth over the last few years. There are now so many of them that it becomes overwhelming to choose the right tool for the job. Among all of the Big Data ready replacements for traditional relational databases (think Cassandra or HBase), there are also a few tools that try to solve a slightly different problem: to provide a centralized log of data, that is both writable by multiple producers and easily readable by multiple consumers.


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Continuous integration for mobile

Babbel

Sven Kroell, Mobile QA Engineer at Babbel & Thanos Karpouzis, Senior Android Developer at Babbel held a talk about Continuous integration for mobile at this year’s Droidcon conference.

The video recording is now to available on Youtube.

API versioning at Babbel

Babbel

Alex MacCaw from Clearbit has written a nice overview about approaches for API versioning. Today we want to elaborate how we deal with API versioning at Babbel.

From the three wide-spread options (using the URL, using a request header, using a dynamic date), we have chosen to go for using URLs. This is the most straightforward solution with minimal overhead for clients.

In addition to a major version, we opted to use a Semantic Versioning approach.


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Babbel @Tech Startup JobsFair 2015 in Berlin

Barbara –

Babbel @Tech Startup JobsFair

Babbel’s Tech and HR teams will be at the Tech Startup JobsFair Berlin Spring 2015 looking for top talents! Babbel is a highly people-oriented company with a strong learning culture. At Babbel, you have the opportunity to work with some of the top talents in the industry, on a highly advanced technology stack that is constantly evolving to keep up with the cutting edge of new developments.

All this is only possible thanks to the team we have put together here at Babbel. Tech team members always participate in the recruitment process, and follow up with mentoring programs for new hires.

Babbel developers take part in great local events and international conferences. Maybe you will be representing us at the next one! But first, come and meet our team at the event, including Boris Diebold, VP Engineering, who will be there to give a quick introduction to the company and answer any questions you may have about working at Babbel.

The Tech Startup JobsFair Berlin is on May 27th 2015, you can sign up now on Eventbrite – and if you’re a top software engineer, we look forward to meeting you there! Check out also our Jobs at Babbel.

Babbel @Tech Startup JobsFair