Jens Oberender

Freelance Java Developer / DevOps Engineer

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Leipzig, Germany

Experience

Jun 2024 - Mar 2025
10 months
Remote

Freelance Java Developer / DevOps Engineer

Undisclosed defense company

  • Expanded OSGi modules in a complex communication solution
  • Debugged communication with Wireshark and remote debugging in the JENS test environment
  • Migrated tests from TestNG to JUnit 5 using Mockito and AssertJ
  • Updated vulnerable dependencies and improved code quality
  • Made changes to the Vaadin frontend
  • Increased test coverage
Sep 2022 - Apr 2024
1 year 8 months
Leipzig, Germany

Freelance Java Developer

Bosch

  • Improved data quality of an e-mobility platform
  • Analyzed data in MongoDB and performed various cleanups with Python scripts
  • Made adjustments and optimizations to several data-processing microservices
  • Handled supply chain security and upgraded dependency and JDK versions
Jun 2022 - Nov 2022
6 months

Freelance Java Developer

Zyres

Mar 2022 - Aug 2022
6 months

Freelance Java Developer

CrossEngage

Jul 2021 - Feb 2022
8 months

Freelance Java Developer

MediaMarktSaturn

  • Extended various microservices and deployed them to Google Cloud (GCP)
  • Updated Spring Boot and leveraged additional GCP features
  • Load tested a service and optimized it using Redis cache for higher loads
  • Introduced testing and code quality practices in the team
Apr 2021 - Jun 2021
3 months

Freelance Java Developer

1&1 Mail & Media Development & Technology GmbH

  • Further development of an existing web application in an 8-person Scrum team
  • Adaptation of microservices using TDD
  • Maintaining high coding standards with the help of Sonar
Feb 2021 - Apr 2021
3 months

Freelance Java Developer

The unbelievable Machine Company

  • Increase test coverage of an existing web application from 13% to 82%
  • Update dependencies using Maven and OWASP dependency checks
Aug 2020 - Jan 2021
6 months

Freelance Java Developer

Elinvar GmbH

  • Further development of various microservices for data import and processing
  • New development of a service for importing and archiving securities documents
  • Optimization of the build process regarding code coverage
  • Smooth migration of microservices to the Spring Boot framework
Feb 2020 - Jul 2020
6 months

Freelance Java Developer

IT Sonix Custom Development GmbH

  • Development of a billing system for an energy company in a five-person Scrum team
  • Refactoring components and adding new features
  • Improving automated quality control
  • Documenting business logic and securing it with appropriate tests
Aug 2019 - Nov 2019
4 months

Senior Java Developer / DevOps Engineer

Pamyra GmbH

  • Further development of a microservice architecture based on Spring Boot and Kubernetes
  • Expansion of logging and monitoring based on the ELK stack
  • Implementation of quality control and increase of test coverage
  • Refinement of the development process
May 2018 - Aug 2019
1 year 4 months

Senior Java Developer / Project Owner

Kiwigrid GmbH

  • Analyze requirements and develop appropriate projects with stakeholders
  • Evaluate different alerting and stream processing frameworks
  • Develop a driver to connect special customer hardware to the Energy Manager
  • Set up a cloud instance in Google Public Cloud using Kubernetes
Sep 2017 - Apr 2018
8 months

Lead Java Developer

cognitix GmbH

  • Lead an international team of 4 Java developers
  • Develop a system to process and visualize network traffic data
  • Prepare, normalize, and aggregate data with Kafka and Apache Flink
  • Coordinate with other teams and handle project management
  • Plan and assign tasks
  • Configure the build system, perform code analysis with SonarQube, and deploy with Docker
Feb 2015 - Aug 2017
2 years 7 months

Software Developer / DevOps Engineer

tarent solutions GmbH

  • Work on a legacy web application based on Velocity with a Lucene backend and Oracle database
  • Standardize code style and revise the release cycle
  • Provide crisis support through log file and performance analysis
  • Extend a Spring MVC web application and further develop the VerA.Web product
  • Revamp the deployment process using Docker and Ansible
  • Contribute to the company-wide build and Maven repository infrastructure
  • Provide DevOps support in Deutsche Telekom's Internet-of-Things project with deployment, monitoring, load, and performance tests
  • Participate in open source and software quality focus topics
Oct 2014 - Dec 2014
3 months

Software Developer

Aperto AG

  • Develop CMS (Magnolia) projects in a 7-person agile team
  • Customize a Maven archetype, improve the build process, and implement Selenium tests
Sep 2011 - Sep 2014
3 years 1 month

Software Developer

Pinguin AG

  • Work in a 5-person Scrum team with a product owner and designer
  • Develop an Android app using Maven, Android Annotations, and ActionBar Sherlock
  • Implement the REST backend in GlassFish with Spring and Jersey
  • Create OSGi server modules with Spring and Hibernate
  • Install and connect a search and logging server using ElasticSearch and Graylog2
  • Follow test-driven development and pair programming
  • Set up and maintain the build system (Jenkins, Nexus, Sonar, Git)
  • Collaborate with a team in Thailand through training, code reviews, and interface provisioning
May 2010 - Sep 2011
1 year 5 months

Software Developer

Prodato Integration Technologie GmbH

  • Refactoring and cleaning up a process management software and presenting it to the client
  • Migrating projects to Maven
  • Co-developing a JSF interface for an Oracle data warehouse
  • Short-term assignment in the SAP BW and BSP area at Siemens Healthcare
Sep 2007 - Apr 2010
2 years 8 months

Software Developer in the Development & Research Department

Keynote Sigos GmbH

  • Co-developed a Swing interface as well as performing bug analysis and fixes
  • Integrating a mapping interface in the project team
  • Migrating the backend from a TCL web server to a Tomcat servlet with XML protocol implementation
  • Introducing tests with JUnit and an automated build system
  • Switching the build tool from Ant to Maven and moving the code repositories to Git
Jun 2000 - Aug 2005
5 years 3 months

Working student and intern in the Support and IS&T Department

SUSE Linux GmbH

  • Linux support and server administration
  • PHP development with a MySQL database
  • Supporting the administration of the PKI infrastructure

Skills

  • Java

  • Maven

  • Linux Administration

  • Spring Boot

  • Html & Css

  • Jenkins

  • Continuous Integration

  • Git

  • Junit 5

  • Mockito

  • Assertj

  • Lombok

  • Sonarqube

  • Test Driven Development

  • Mysql

  • Logging (Log4j2, Slf4j)

  • Shell Script

  • Ansible

  • Jenkins Pipeline

  • Github Actions

  • Gitlab Ci

  • Gradle

  • Google Public Cloud

  • Kibana

  • Docker

  • Jira/confluence

  • Python

  • Arduino And Microcontrollers

  • Rabbitmq

  • Mongodb

  • Elasticsearch

  • Kafka

  • Kubernetes

  • Openapi

  • Postgresql

  • Javascript

  • Apache Flink

  • Selenium

  • Vaadin

  • Very Good Java Skills

  • Very Good Linux Skills

  • Continuous Integration With Github Actions, Jenkins Or Gitlab Ci

  • Devops With Ansible, Docker, Kubernetes And Cloud (Gcp And Aws)

  • Database Knowledge (Especially Mysql And Postgresql)

  • Geographic Information Systems (Gis)

  • Driver Programming

  • Logging And Monitoring

  • Test-driven Development

  • Software Quality Assurance With Sonar, Owasp And Other Tools

Languages

German
Native
English
Intermediate

Education

Oct 2003 - Jun 2008

Georg-Simon-Ohm-Fachhochschule

Diploma in Computer Science (FH) · Computer Science · Nuremberg, Germany

Oct 2000 - Jun 2003

Friedrich-Alexander-Universität Erlangen-Nürnberg

Diploma in Computer Science (not completed) · Computer Science · Erlangen, Germany

Jan 1996 - Mar 1996

Student exchange

Melbourne, Australia

...and 2 more

Certifications & licenses

Java Web Hacking & Hardening

Maven

Novell Certified Linux Administrator

Linux Professional Institute LPIC-1

VHS course: Linux in the network

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