Coaching and training for scalability and performance optimization of Java EE backends and REST APIs for provisioning of virtual IaaS infrastructure
Under my guidance, the performance under load was improved by factor 50
Guided the teams conceptualizing the migration to a microservice architecture
Supporting the implementation of microservices with Quarkus 2.0, Java 16, and GitHub actions for build automation
Designed the next evolutionary stage of the company?s public REST API (?IONOS Cloud API?)
Planned and implemented zero downtime deployment for the legacy monolith
Migration of the website
Adoption of the content management system to changed SEO requirements and updated third-party APIs
Implementing new features for the portal
Moving the build automation from Jenkins to GitHub Actions
Regularly publishing articles about Java programming, algorithms and data structures
Published several video tutorials
2009 - 2019: Setting up the agile IT team
Role: Founder & CTO
Customer: on request
Tasks:
Setting up the agile IT team (Scrum); responsibility for up to 15 employees
Development of a highly scalable, maintainable, and customizable content management system
Continuous upgrades of the codebase 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 an advertising infrastructure as a microservice architecture with Spring Boot, Spring Cloud, Netflix OSS, Elasticsearch and RxJava, operated in a Kubernetes cluster
Development of the AndroidPIT App Center, a Googleindependent app store with various payment options and the ability for developers to offer discounts and promotions ? pre-installed on devices of many manufacturers
Development of the first web directory of Android apps in 2009 ? before the Google Play Store existed as a website ? by reverse-engineering the Android App Store
Skills:
Java 11, Spring Boot, Spring Cloud, RxJava, JPA, Hibernate, MySQL, Elasticsearch, Filebeat, Kibana, Tomcat, HAProxy, Kubernetes, Docker, GlusterFS, Ansible
2004 ? 2009: Development of the website and the logistics and payment backend
Role: Founder & CTO
Customer: on request
Tasks:
Development of the website and the logistics and payment backend for the game rental platform ?GameAbo?.
Development of a browser-based MMOG
Development of the backend for a browser-based 3D community
Skills:
Java, Spring Framework, Hibernate, Tomcat, MySQL
2002 ? 2004: various Windows projects
Role: Team Leader Windows Client Development
Customer: 1&1 Internet AG
Tasks:
Built a development team for various Windows projects
Continued development of the ?GMX SMS Manager?
Re-implemented the entire SMS backbone of the UI Group
Skills:
Java, JMS, JBoss (now WildFly), Borland C++ Builder
2000 ? 2002: Windows application
Role: Founder & CTO
Customer: on request
Tasks:
Developed the Windows application ?GMX SMS Manager?, the first paid online messaging service in Germany.
Acquired by 1&1 Internet AG in October 2002
Skills:
Java, JDO, Tomcat, Oracle DB, Borland C++ Builder
1999 ? 2000: J2 Global
Role: Software Developer
Customer: JFAX Germany GmbH
Tasks:
Local branch of J2 Global, a unified messaging platform provider
Built up the German portal ?jfax.de?.
In 2000, business was handed over to the parent company
Skills:
Java, JSP, JRun, Oracle DB
1999 - 1999: Development of a Windows application
Role: Founder & CTO
Customer: on request
Tasks:
Development of a Windows application
Development of the backend software
Skills:
Java, JRun, Oracle DB, Visual C++
practical computer science
algorithms and data structures
database systems
1997 ? 1999
Amazon.com
Intern and Graduate Student
Diploma thesis at Amazon.com in Seattle, USA
Profile
When systems grow from thousands to millions (or billions) of users and transactions, they often reach their scalability limits
Even experienced developers find it challenging to eliminate the resulting performance bottlenecks. Constant demands for new features and limited time don?t leave room for building the skills required to design architecture and code for massive growth
This is where I have my field of expertise ? as a developer and coach
Having over two decades of experience in scalable Java enterprise applications ? from monoliths to complex microservice architectures ? and with a focus on advanced topics such as concurrency, reflection, the Java memory model, and garbage collection ? I will support and coach your teams to push them beyond their limits
With my background as founder and CTO of several start-ups and SMEs, I always strive to understand requirements from a business perspective As a team lead and freelancer, I have led and supported large corporate teams working on enterprise-level applications
This Is What I Can Do For You
Development
I will help you find solutions where others are stuck
I work with your developer teams, supporting them in solving performance and scalability issues
If you wish, I get a picture of your developers? skills in pair programming and prepare coaching and training tailored to your organization
Coaching
I will coach your teams individually and on target
In one-on-one sessions or small groups, I analyze your teams? strengths and weaknesses in light of your company?s tasks
Together we turn the weaknesses into strengths
Optionally, I prepare training courses for your entire organization
Courses
I will bring your employees up to date on the latest Java technology
Let me teach your teams how to work efficiently with streams and lambdas and how to do concurrency the right way
I?ll train your teams on the new language features released every six months, allowing them to code even faster
Choose from my courses, or let me design customized training for your teams
Main Areas of Expertise
Advanced Java
New language features (currently Java 16: Pattern Matching for instanceof, Records)
Streams, Lambdas
Collections framework incl. queues, deques, concurrent collections
Advanced topics: Concurrency, Performance, Reflection, Java Memory Model, Garbage Collection
Microservices and Enterprise Applications
Java EE / Jakarta EE / MicroProfile (Glassfish, Payara, Quarkus)
Spring Framework (Spring Boot, Spring Cloud, Spring Data)
Providing and connecting to REST APIs (+ GraphQL)
Integration with RDBMs such as MySQL, PostgreSQL with JPA, Hibernate, Panache, EclipseLink
Code Quality
Clean code (SOLID principle)
Design patterns
Test-driven development (JUnit, TestNG, AssertJ, Hamcrest, Mockito, RestAssured, WireMock, Testcontainers, Cucumber)
Static code analysis with PMD, FindBugs / SpotBugs, Checkstyle, SonarQube / SonarCloud / SonarLint, sshgit, Trivy
I?m Passionate About
complex problem solving with attention to detail.
surprising other developers with new approaches to solutions, inspiring and enabling them to create elegant, intuitive, efficient, and maintainable code themselves.
the continuous expansion of my boundaries, knowledge, and skills ? also in other areas of life like entrepreneurship, marketing, productivity, health, and personality development
Coaching and training for scalability and performance optimization of Java EE backends and REST APIs for provisioning of virtual IaaS infrastructure
Under my guidance, the performance under load was improved by factor 50
Guided the teams conceptualizing the migration to a microservice architecture
Supporting the implementation of microservices with Quarkus 2.0, Java 16, and GitHub actions for build automation
Designed the next evolutionary stage of the company?s public REST API (?IONOS Cloud API?)
Planned and implemented zero downtime deployment for the legacy monolith
Migration of the website
Adoption of the content management system to changed SEO requirements and updated third-party APIs
Implementing new features for the portal
Moving the build automation from Jenkins to GitHub Actions
Regularly publishing articles about Java programming, algorithms and data structures
Published several video tutorials
2009 - 2019: Setting up the agile IT team
Role: Founder & CTO
Customer: on request
Tasks:
Setting up the agile IT team (Scrum); responsibility for up to 15 employees
Development of a highly scalable, maintainable, and customizable content management system
Continuous upgrades of the codebase 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 an advertising infrastructure as a microservice architecture with Spring Boot, Spring Cloud, Netflix OSS, Elasticsearch and RxJava, operated in a Kubernetes cluster
Development of the AndroidPIT App Center, a Googleindependent app store with various payment options and the ability for developers to offer discounts and promotions ? pre-installed on devices of many manufacturers
Development of the first web directory of Android apps in 2009 ? before the Google Play Store existed as a website ? by reverse-engineering the Android App Store
Skills:
Java 11, Spring Boot, Spring Cloud, RxJava, JPA, Hibernate, MySQL, Elasticsearch, Filebeat, Kibana, Tomcat, HAProxy, Kubernetes, Docker, GlusterFS, Ansible
2004 ? 2009: Development of the website and the logistics and payment backend
Role: Founder & CTO
Customer: on request
Tasks:
Development of the website and the logistics and payment backend for the game rental platform ?GameAbo?.
Development of a browser-based MMOG
Development of the backend for a browser-based 3D community
Skills:
Java, Spring Framework, Hibernate, Tomcat, MySQL
2002 ? 2004: various Windows projects
Role: Team Leader Windows Client Development
Customer: 1&1 Internet AG
Tasks:
Built a development team for various Windows projects
Continued development of the ?GMX SMS Manager?
Re-implemented the entire SMS backbone of the UI Group
Skills:
Java, JMS, JBoss (now WildFly), Borland C++ Builder
2000 ? 2002: Windows application
Role: Founder & CTO
Customer: on request
Tasks:
Developed the Windows application ?GMX SMS Manager?, the first paid online messaging service in Germany.
Acquired by 1&1 Internet AG in October 2002
Skills:
Java, JDO, Tomcat, Oracle DB, Borland C++ Builder
1999 ? 2000: J2 Global
Role: Software Developer
Customer: JFAX Germany GmbH
Tasks:
Local branch of J2 Global, a unified messaging platform provider
Built up the German portal ?jfax.de?.
In 2000, business was handed over to the parent company
Skills:
Java, JSP, JRun, Oracle DB
1999 - 1999: Development of a Windows application
Role: Founder & CTO
Customer: on request
Tasks:
Development of a Windows application
Development of the backend software
Skills:
Java, JRun, Oracle DB, Visual C++
practical computer science
algorithms and data structures
database systems
1997 ? 1999
Amazon.com
Intern and Graduate Student
Diploma thesis at Amazon.com in Seattle, USA
Profile
When systems grow from thousands to millions (or billions) of users and transactions, they often reach their scalability limits
Even experienced developers find it challenging to eliminate the resulting performance bottlenecks. Constant demands for new features and limited time don?t leave room for building the skills required to design architecture and code for massive growth
This is where I have my field of expertise ? as a developer and coach
Having over two decades of experience in scalable Java enterprise applications ? from monoliths to complex microservice architectures ? and with a focus on advanced topics such as concurrency, reflection, the Java memory model, and garbage collection ? I will support and coach your teams to push them beyond their limits
With my background as founder and CTO of several start-ups and SMEs, I always strive to understand requirements from a business perspective As a team lead and freelancer, I have led and supported large corporate teams working on enterprise-level applications
This Is What I Can Do For You
Development
I will help you find solutions where others are stuck
I work with your developer teams, supporting them in solving performance and scalability issues
If you wish, I get a picture of your developers? skills in pair programming and prepare coaching and training tailored to your organization
Coaching
I will coach your teams individually and on target
In one-on-one sessions or small groups, I analyze your teams? strengths and weaknesses in light of your company?s tasks
Together we turn the weaknesses into strengths
Optionally, I prepare training courses for your entire organization
Courses
I will bring your employees up to date on the latest Java technology
Let me teach your teams how to work efficiently with streams and lambdas and how to do concurrency the right way
I?ll train your teams on the new language features released every six months, allowing them to code even faster
Choose from my courses, or let me design customized training for your teams
Main Areas of Expertise
Advanced Java
New language features (currently Java 16: Pattern Matching for instanceof, Records)
Streams, Lambdas
Collections framework incl. queues, deques, concurrent collections
Advanced topics: Concurrency, Performance, Reflection, Java Memory Model, Garbage Collection
Microservices and Enterprise Applications
Java EE / Jakarta EE / MicroProfile (Glassfish, Payara, Quarkus)
Spring Framework (Spring Boot, Spring Cloud, Spring Data)
Providing and connecting to REST APIs (+ GraphQL)
Integration with RDBMs such as MySQL, PostgreSQL with JPA, Hibernate, Panache, EclipseLink
Code Quality
Clean code (SOLID principle)
Design patterns
Test-driven development (JUnit, TestNG, AssertJ, Hamcrest, Mockito, RestAssured, WireMock, Testcontainers, Cucumber)
Static code analysis with PMD, FindBugs / SpotBugs, Checkstyle, SonarQube / SonarCloud / SonarLint, sshgit, Trivy
I?m Passionate About
complex problem solving with attention to detail.
surprising other developers with new approaches to solutions, inspiring and enabling them to create elegant, intuitive, efficient, and maintainable code themselves.
the continuous expansion of my boundaries, knowledge, and skills ? also in other areas of life like entrepreneurship, marketing, productivity, health, and personality development