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Order management
01/2021 | MediaMarktSaturn | Commerce
MacOS, Linux, GCP, Kotlin, Kubernetes, Helm, Terraform, Jenkins, GitOps, Git/Github, Kafka, Apache Artemis, DDD, FP, TDD, REST, OpenAPI
Provided Infrastructure as Code with Terraform modules on GCP.
Described applications with Helm charts/releases.
Migration to new technology stack/Implementation of new features
10/2019 – 05/2020 | Autoscout24 GmbH | Commerce
MacOS, Linux, AWS, Scala, Play, Jenkins, Git/Github, DDD, FP, TDD, Oauth, Datadog, REST, OpenAPI
Designed, implemented, and extended microservices in Scala, deployed, and operated them on AWS, and monitored them with Datadog.
Researched and compared 3rd party providers for identity management.
Documented important work aspects in the company wiki.
Data export to DATEV-Lodas format
03/2019 – 09/2019 | Personio GmbH | IT
MacOS, Linux, Kotlin, Git/Gitlab, Gradle, REST, JSON, DDD, TDD, OAuth, Postgres, Kubernetes/Helm, AWS, New Relic, Spring, Junit 5, Wiremock, Fuel
Designed and implemented a microservice that maps Personio Payroll data to Datev-Lodas values and exports them in an ASCII text file.
Integrated other microservices.
Wrote database migrations scripts.
Documented the Personio Payroll API with the OpenAPI format.
native Android logistics app for dispatchers and fleet managers
07/2018 – 02/2019 | RIO the logistics flow GmbH | Automotive
MacOS, Linux, Kotlin, Android, AWS, Git/Bitbucket, REST, JSON, DDD, TDD, spek, Espresso, OAuth, here sdk, Firebase, Crashlytics, Jira
Designed and implemented basic app architecture and features.
Deployed the app to the Google Play Store.
As the first engineer in the new team I helped shape efficient team communication and working style (Kanban).
Worked closely together with UX designers, product managers, sales people, and the enterprise architect.
Promoted the mobile first approach in the organization.
Delivered software fast and gathered and incorporated user feedback.
Documented important work aspects in the company wiki.
new access management application on top of an identity technology; Android app for NFC token writing
07/2017 – 06/2018 | BlueID technology GmbH | IT
MacOS, Linux, Golang, Kotlin, Android, Terraform, Gitlab, Prometheus, Nomad, AWS, Docker, REST, JSON, DDD, TDD, OOP/FP, NFC, OAuth, Jira
Set up the required infrastructur on AWS: CI/CD, monitoring, logging, mattermost, upsource.
Designed and implemented backend services in go. Deployed, operated, and monitored them.
Designed and implemented a native Android app with Kotlin for writing tokens onto NFC cards.
Documented important work aspects in the company wiki.
Inspired the team to switch from Scrum to Kanban in order to become more efficient still.
migration to new technology stack; categorization engine for listings
07/2015 – 06/2017 | Autoscout24 GmbH | Commerce
MacOS, Linux, AWS, Scala, Akka, Play, Kafka, Spark, Drools, Redis, Go CD, FP, OOA/OOD, Ruby, TDD, Oauth, Datadog
Designed and implemented micro services in Scala, deployed, and operated them on AWS, and monitored them with dashboards and Datadog.
Documented important work aspects in the company wiki.
Taught co-workers the basics of Scala.
migration of build processes to Gradle
02/2015 – 06/2015 | Fiducia & GAD IT AG | Finance
PC/Win 7, Linux, Gradle, SVN, Asciidoc, OOA/OOD, Java, UML, SQL, TDD
Wrote database migration and linux scripts for build processes.
Documented processes in the company CMS with Asciidoc.
extension of banking applications
03/2014 – 01/2015 | Fiducia & GAD IT AG | Finance
PC/Win 7, Java 6, Tomcat 7, JBF 5.2/5.3, Eclipse 3.7, RSA 7.5, SVN, Junit/Mockito, xstream, OOA/OOD, UML, JBF, TDD
Designed and implemented requirements according to new government regulations.
Added printing capabilities to the application.
Documented important aspects in the company wiki.
Customer loyalty platform 'Stickin'
08/2012 – 07/2014 | STICKIN AG | Commerce
PC/Win 7 / 8, Linux, Java 7, Tomcat 7, Eclipse 4.2, IntelliJ 12, Git, Postgres, ActiveMQ, MongoDB, Guice, Enterprise Architect, Jira, JSON, REST, Shiro, Gradle, Jenkins, New Relic, MixPanel, Junit/Mockito, OOA/OOD, UML, HTML5, Servlets, REST, Scrum, OAuth
Co-founded the company and took over responsibility for all aspects of development and operations (CTO).
Designed the application and platform architecture and implemented the basic framework.
Got the platform up and running successfully and reliably.
Set up and led a team of engineers including remote workers and defined all necessary work processes.
Responsible for choosing the right tools and technology for development and operations.
Coached and mentored team members.
Took care of security aspects, defined the REST API, and set up a thourough test process.
Documented all important information in the company's wiki.
New banking application 'credit reporting'
05/2012 – 02/2013 | Fiducia & GAD IT AG | Finance
PC/Win 7, Java 6, Tomcat 6.2, JBF 4.4, Eclipse 3.5, RSA 7.5, SVN, OOA/OOD, UML, JBF, JDBC/JPA, SQL
Analyzed and modelled all business processes.
Designed and implemented the GUI and application and connected it to the backend.
Designed efficient SQL commands for database accesses.
Eclipse RCP based application framework for a merchandise management system
11/2006 – 04/2012 | Infokom GmbH | Commerce
PC/Win XP/Vista/7, Java 5/6, Eclipse 3.4 - 3.6, Progress, Enterprise Architect, CVS, Trac, OOA/OOD, UML, Progress Dataobjects, Eclipse RCP
Designed and implemented an efficient application framework architecture and state-of-the-art GUI.

Continuously refactored and improved the codebase quality.
Coached and mentored juniour coworkers.
Defined and documented development conventions and work artefacts.
Migration and green field development of several banking applications
6/2003 – 5/2006 | Fiducia & GAD IT AG | Finance
PC/Win XP, Java 3, Tomcat 4.0, JBF 4.1, Eclipse 2.1, Innovator 7, CVS, UML, JDBC, SQL
Designed and implemented the GUI and application and connected it to the backend.
Designed the database structure and efficient SQL commands for database accesses.
Defined development conventions and coached and mentored junior coworkers.
Refactored and improved the codebase quality.
Vehicle brake construction application
2003-03 ... 2003-12, 2001-01 ... 2002-04, 1999-09 ... 2000-12 | Robert Bosch GmbH | Automotive
PC/Win NT, Java 1.4, Eclipse 2.1, Argo UML, JAXB 1.0, Swing, UML, XML, Schema, Visual Age 3.5, VisiBroker 4.2, Personal Oracle 8i, CVS, OOA/OOD, SQL, JDBC, Domino 5.0, Corba
Developed a sub system for searching and filtering brake components.
Added a front-end for simulating selected brake components.
Created an efficient GUI for loading and storing brake components and sessions.
Added user permission management.
Defined XML vocabularies with schemas, matching parsers, and generators.
Wrote efficient SQL queries for accessing all required artefacts.
Wrote developer and user documentation.
Planned and managed the project.
Marketing web application
2002-09 | Gmünder Ersatzkasse (now Barmer) | Insurance
PC/Win NT, IntelliJ Idea, Resin, Java, JSP, JavaScript, servlets
Extended existing JSP pages and adapted controller servlets.
Added Javascript functionality.
New creditworthiness rating banking application for supporting the Basel II accord
2002-06 ... 2002-08 | Fiducia & GAD IT AG | Finance
PC/Win 2000, Java 1.3, Tomcat 4.0, JBF 4.0, Forte, Innovator, Xerces 2.0, Argo UML, CVS, JBF, JavaHelp, XML
Designed and implemented the computing core for calculating a creditworthiness rating.
Defined all necessary XML vocabularies and implemented the matching parsers.
Implemented scheduler based processing of temporary results (cronlet).
Integrated online help.
developing UML course material, leading 4 day courses on OOAD with UML
2001-03, 2001-05 | Object International Software GmbH | IT
PC/Win 2000, Together/J 4.1, 5.0, UML, OOA/OOD, RUP, design patterns
Updated UML constructs and diagrams to Version 1.4.
Added a development process (Rational Unified Process).
Defined a case study for analysis and design to have a consistent scenario for course participants.
Wrote a chapter on design patterns.
Held the class twice.
New multimedia managment and streaming application
2000-01 … 2000-07 | MediaConsult | Media
PC/Win NT, Java 1.1.8, Domino 5.0, OOA/OOD, JMF, servlets, Lotus Domino
Designed and implemented the server backend and frontend.
Implemented an access layer to a Domino server.
Chip card framework (OpenCard Framework)
1997-12 … 1999-06 | IBM Germany R & D | IT
PC/Win NT, RS6000/AIX 4.2, Linux RedHat, Rational Rose 4.0/Together/J 2.0, Java 1.1.6, Java Visual Cafe 2.5, Visual Age for Java 2.0, MS VC++ 5.0, UML, OCF, CVS
Designed and implemented the smart card terminal part of the framework.
Co-authored "How to write a CardTerminal class for simple and complex readers in an OpenCard Environment" in JavaWorld 1/1999.
Took care of the CVS server and release builds.
Wrote documentation for the framework.
Vehicle documentation application
1997-06 … 1997-11 | T-Systems | Automotive
PC/Win NT, RS6000/AIX 4.1, HP9000/HP-UX9.3, SGI Indigo/Impact/IRIX 6.2, MS VC++ 4.0
Designed and implemented an abstraction layer for multithreading functionality for Windows and different flavours of Unix.
Web based IRC chat client
1996-05 … 1996-11 | HexMac International GmbH | IT
PC/Win NT, Sparc/Solaris 2.5, Rational Rose 3.0, Java 1.0, AWT, IRC, HTML
Designed and implemented the GUI.
Developed custom AWT UI elements.
Wrote a proxy server to connect to existing IRC servers.