Internship: Babiel GmbH

My required university internship (Fachpraktikum) took place at Babiel GmbH in Düsseldorf — a digital agency with 100+ employees specialising in online communication, digital marketing, and e-commerce. I had already been working there as a working student since May 2019, so I was able to hit the ground running from day one.

The internship ran from April to August 2020 — fully remote due to COVID-19 — for a total of 19 weeks. I worked as a backend developer on the agency’s largest active project: migrating the Wiener Tourismusverband (Vienna Tourism Board) website and all of its content into the CoreMedia CMS.

Project Context

CoreMedia’s backend is Spring-based, so Java was the primary language throughout. The CMS Studio — the editorial interface used by content editors and clients — is built on ExtJS and configured using ActionScript/mxml, which was new territory for me at the start. Frontend templates were written in Freemarker and Handlebars. The team worked in 3-week SCRUM sprints with full ceremonies: daily standups, refinements, sprint reviews (with live client demos), planning, and retrospectives.

Contributions

Studio Customisations (CMS Forms & CKEditor)

A large share of my tickets involved extending the CoreMedia Studio — adding new content fields and adapting editorial forms to match the client’s requirements. This meant working in ExtJS, a large and sparsely documented framework I had no prior experience with. I relied heavily on colleagues, trial and error, and browser debugging to get up to speed, and eventually reached a point where smaller Studio tasks had become routine.

The most involved work in this area was customising the CKEditor rich text editor built into the Studio:

• Reverse-engineered the original JavaScript dialog code to recreate link dialogs in ExtJS/ActionScript form
• Added a Button Link variant to both the internal and external link dialogs
• Implemented automatic CSS class assignment (pdf, extern, etc.) via a Java richtext filter that reads the XML produced by the editor and decorates links before HTML output
• Added a Vienna City Card toolbar button that injects a branded link with its icon directly into the editor and the rendered page

Java Backend Logic

Beyond Studio work, I implemented several Java components in the CoreMedia backend:

• Facades — passed calculated or composed data to Freemarker/Handlebars frontend templates
• Validators — checked that required content fields were correctly filled before publishing
• Upload interceptor — extended the image upload process to assign sequential unique image numbers (with thread-safety) and extract copyright metadata from EXIF data, writing both into CoreMedia content fields
• Richtext filters — processed XML-formatted rich text produced by the CKEditor to prepare it for clean HTML output

All Java work was accompanied by Spock/Groovy unit tests.

Infrastructure & Code Quality

Early in the internship, I took ownership of setting up a SonarQube build-breaker for the WTV project. This turned into a broader piece of work: the existing VM was decommissioned, a new Sonar instance had to be provisioned, and the test coverage reporting broke with the newer Java/Maven version. After a long round of research and coordination with colleagues and the sysadmin team, I resolved the coverage issue and migrated the build-breaker configuration across all Babiel projects.

I also set up and tested the GitLab CI pipeline for the external frontend team’s deployment workflow, and managed staging deployments at end of each sprint — coordinating timing with the team and client, since client QA and acceptance testing happened on that environment.

Agile Process

As a full participant in the SCRUM process I presented completed stories directly to the client at nearly every Sprint Review. I also contributed to evolving the refinement format — we identified that not enough stories were being estimated per session and shifted to a model where developers prepared story summaries and implementation proposals in advance.

The full internship report (in German) is available below.