Programming has been my passion since I was eight years old. Via Basic, Turbo Pascal, Delphi, and C++, I came to Java in 1996.
My focus is on Java backend development, especially on the technologies and frameworks mentioned below.
I have founded several startups, and, from 2009 to July 2019 I was a board member and CTO of AndroidPIT, the world’s largest multilingual Android community, with responsibility for the IT team with up to 15 employees and always as part of the development team.
Since August 2019, I am working as Java Backend Specialist Freelancer.
What drives me
Main areas of expertise
Career and technologies
Since August 2019:
Freelance programmer and trainer.
An extract of my current projects:
- IONOS: Optimizing the performance of the Java-based backend for provisioning of virtual IaaS infrastructure. Technology: Java EE, Glassfish. Result: Improved the performance of the provisioning logic under load by factor 50; improved the performance of multiple REST API endpoints by up to factor 35.
- IONOS: Converting Groovy code to Java.
- IONOS: Planning the migration to a (micro-)service-oriented architecture with Quarkus and Eclipse MicroProfile.
- IONOS: Conception of the adaptation of the Java backend to enable zero downtime deployment.
- AndroidPIT: Maintaining the infrastructure and implementing features for the portal. Technologies: Java 11, Spring Framework, Spring Boot, MySQL, Elasticsearch, Kubernetes.
2009 – 2019:
Board member and CTO of Fonpit AG in Berlin, operator of the world’s largest multilingual Android community, AndroidPIT with approx. 50 employees.
- Setting up the agile IT team (Scrum) and responsibility for up to 15 employees.
- Development of a high-performance, scalable and customizable content management system for AndroidPIT since 2009 – with the Spring Framework, Hibernate ORM, Tomcat, MySQL and Elasticsearch in the backend.
- Continuous upgrades of the codebase from Java 6, Spring Framework 2.5, and Hibernate 3.2 in 2009 to Java 11, Spring 5.1, Spring Boot 2.1, Spring Cloud Greenwich, and Hibernate 5.3 in 2019.
- Adaptation of the entire IT infrastructure to the requirements of the EU-GDPR in 2018.
- Development of the native advertising format “NEAds – Native Engagement Ads” since 2016 – implemented them as a Microservice architecture with Spring Boot, Spring Cloud, Netflix OSS, Elasticsearch and RxJava – and operated in a Kubernetes cluster.
- Development of the AndroidPIT App Center, a Google-independent app store for Android apps with various payment methods and the ability for app developers to offer discounts and promotions, – pre-installed on devices of many manufacturers in 2010.
- Development of the first web directory of Android apps in 2009 – even before the Google Play Store existed as a website – by reverse-engineering the Android App Store.
- Setting up CI/CD pipelines with Jenkins and the Jenkins Job DSL.
- Automation of the configuration and administration of the IT infrastructure with Ansible.
2004 – 2009:
Founder, board member and CTO of eleisure AG in Karlsruhe, a holding company for online gaming.
Development of the game rental platform “GameAbo,” the browser-based MMOG “Feenix – The Age of Pirates,” which was voted Browser Game of the Year 2005 by 50,000 readers of the online magazine “Galaxy-News,” and the browser-based 3D flirt community “Bailamo.” Development of the backends based on Java, Spring Framework, Hibernate ORM, Tomcat, and MySQL. Implementation of the Bailamo 3D Frontend as a Java Applet with OpenGL and JOGL.
2002 – 2004:
Team leader for Windows client development at 1&1 Internet AG in Karlsruhe.
Responsible for the further development of the SMS Manager and the re-implementation of the entire SMS backbone of the United Internet Group based on Java, JMS, and JBoss (now WildFly).
2000 – 2002:
Founder, Managing Director and head of software development of W+R Software GmbH in Regensburg, developer of GMX SMS Manager, the first paid online SMS service in Germany.
Implementation of the backend with Java, JDO, Tomcat, and Oracle DB. Development of the frontend with Borland C++ Builder.
Acquisition of the company by 1&1 Internet AG in October 2002.
1999 – 2000:
Head of software development at JFAX Germany in Regensburg, the local branch of J2 Communications, provider of a Unified Messaging platform.
Setup of the German portal “jfax.de” with Java, JSP, JRun, and Oracle DB.
In August 2000, the business was handed over to the parent company in the USA.
Founder and CTO of Cleverlearn Inc., provider of an online language learning platform based in Los Angeles.
Development of the backend functionality with Java, the servlet engine JRun and Oracle DB as database system. Implementation of the frontend with Visual C++.
1994 – 1999:
Studied Computer Science at the Technical University Ilmenau with a focus on practical computer science, algorithms and data structures, and database systems.
Diploma thesis with the title “Conception, comparison, and evaluation of different approaches for the data management of an adaptive agent, based on predictive data mining” at Amazon in Seattle, USA.
I graduated as Diplom-Informatiker (corresponds to Master of Science) with distinction after nine semesters.
ID4me Summit, August 2018:
- at heise online (in German):
Login mit ID4me: Dezentrales Single Sign on fürs Internet
(Download als PDF-Datei)
- at datensicherheit.de (in German):
ID4me: Management von digitalen Identitäten
(Download als PDF-Datei)