Rene is available for hire

Rene Hartmann

Verified Expert in Engineering

Software Developer

Location

Edderitz, Saxony-Anhalt, Germany

Toptal Member Since

February 21, 2022

Rene is a goal-driven agile developer with 15+ years of experience designing and implementing successful, scalable, and performing Java-based solutions. He is keen on writing clean and maintainable code and is mainly interested in working with high-performance, scalable, low-latency distributed applications. Rene believes efficient working processes, mentoring, and teamwork are crucial for successfully developing and deploying solutions.

Distributed Systems Java Spring XML SQL Microservices Kubernetes Full-stack DevOps Engineer GitOps Linux JavaScript Git Jira GitHub Camunda Cloud Foundry

Portfolio

ING Group

Java, Spring Boot, Red Hat OpenShift, Jira, Azure DevOps, Kubernetes, Helm...

MediaMarktSaturn Retail Group

Spring Boot, Java 11, Git, Google Cloud Platform (GCP)...

Credit Suisse

Spring Boot, Hadoop, Git, Java, Jira, SQL, Distributed Systems

Experience

Java - 20 years Git - 10 years Spring - 10 years Scrum - 10 years Spring Boot - 6 years Docker - 4 years React - 4 years Google Kubernetes Engine (GKE) - 2 years

Availability

Part-time

Preferred Environment

Linux

The most amazing...

...web application I've build is a global trading management app.

Work Experience

Java DevOps Engineer

2022 - PRESENT

ING Group

Developed CI and deployment pipelines and related microservices.
Created a UI to deploy the company's apps into OpenShift clusters.
Set up a gateway to make services available to consumers running in different OpenShift clusters.

Technologies: Java, Spring Boot, Red Hat OpenShift, Jira, Azure DevOps, Kubernetes, Helm, Apache Kafka, Microservices, Spring Cloud Gateway, Client-server Model, SQL, Camunda BPM, Distributed Systems

Senior Java Developer

2021 - 2022

MediaMarktSaturn Retail Group

Created and maintained a Spring Boot-based service to orchestrate the shipment process of online orders during the company's critical checkout process.
Integrated the service into the company-wide microservice architecture and deployed it to the Google Cloud Platform with Kubernetes.
Persisted shipment data in PostgreSQL and MongoDB and integrated other services via REST and Pub/Sub.

Technologies: Spring Boot, Java 11, Git, Google Cloud Platform (GCP), Google Kubernetes Engine (GKE), PostgreSQL, MongoDB, Gatling, Postman, IntelliJ IDEA, Scrum, Docker, Jira, GitHub, GitOps, DevOps Engineer, SQL, Distributed Systems

Senior Java Developer

2019 - 2021

Credit Suisse

Consolidated the bank's risk data in a central system. Processed data stored in a Hadoop cluster using an in-house cloud platform and data pipeline architecture.
Designed and developed REST services that enable data extraction to client systems for further analysis.
Developed a distributed architecture using Spring Boot components to scale the extraction process compliant with the applications' service level agreements.

Technologies: Spring Boot, Hadoop, Git, Java, Jira, SQL, Distributed Systems

Senior Java Developer

2014 - 2019

UBS

Developed a data distribution application for instrument and client data, amongst all trading applications in the front-office equities IT department. Implemented Java core multithreaded and GC-free low-latency applications.
Implemented a Spring Boot-based web service for data collection and distribution. Developed T-SQL stored procedures for data persistence.
Developed the front end with HTML5, Bootstrap, jQuery, and React. Deployed Spring Boot services to CloudFoundry.

Technologies: React, Microsoft SQL Server, Cloud Foundry, Bootstrap, jQuery, Spring Boot, Java, Jira, Team Leadership, GitHub, HTML, JavaScript, Full-stack, XML, UML, SQL, Distributed Systems

Senior Java Developer

2013 - 2014

Wiley

Designed and implemented new shared OSGi bundles to extend CMS capabilities and connect to RESTful web services.
Executed the performance tuning of the back-end mapping components to achieve higher throughput and lower the required CPU time with YourKit, Profiler, JMeter, and VisualVM.
Identified and solved permanent generation memory errors caused by hot deployments within the OSGi container.

Technologies: DotCMS, Spring, Java, Jira, Team Leadership, Management, HTML, JavaScript, Full-stack, SQL, Distributed Systems, RabbitMQ

Senior Java Developer

2000 - 2011

IBM

Implemented Java core multithreaded front-end and back-end components with several interfaces to other systems based on REST, web services, messaging, and email.
Designed and developed a dynamic authorization component to let the customer change the application's behavior on an ad-hoc basis.
Developed a thread pool to distribute performance-intensive asynchronous workloads to several concurrent working threads.

Technologies: Java, IBM Db2, JEE, Hibernate, Spring, Jira, Team Leadership, HTML, JavaScript, Full-stack, Web Services Description Language (WSDL), Distributed Systems

Experience

Git Lock

https://github.com/hartrene/git-lock

I've worked on the Git Lock project, a Shell-based server and client to support the central locking of any files stored in Git. It was written to address some project needs related to simultaneously preventing changes on Excel binary files from several developers.

Education

2007 - 2011

Master of Science Degree in Computer Science

Darmstadt University of Applied Sciences - Darmstadt, Germany

Certifications

JANUARY 2019 - PRESENT

Java 8 OCP Certificate

Sun Microsystems

JANUARY 2008 - PRESENT

Sun Java 1.6 Certified Programmer

Sun Microsystems

JANUARY 2004 - PRESENT

Sun Java 1.4 Certified Programmer

Sun Microsystems

Skills

Libraries/APIs

React, jQuery, Node.js

Tools

Git, Jira, GitHub, Camunda BPM, Shell, Google Kubernetes Engine (GKE), Gatling, Postman, IntelliJ IDEA, Helm, RabbitMQ

Frameworks

Spring, Spring Boot, Hibernate, Bootstrap, Hadoop, Ruby on Rails (RoR)

Platforms

Kubernetes, Linux, DotCMS, JEE, Google Cloud Platform (GCP), Docker, Amazon Web Services (AWS), Red Hat OpenShift, Apache Kafka

Languages

Java, XML, SQL, HTML, JavaScript, UML, Web Services Description Language (WSDL), Java 11

Paradigms

Microservices, REST, Scrum, Management, Azure DevOps

Storage

Microsoft SQL Server, IBM Db2, PostgreSQL, MongoDB

Other

Distributed Systems, Team Leadership, Full-stack, GitOps, DevOps Engineer, Client-server Model, Cloud Foundry, Spring Cloud Gateway, Quarkus

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