Amazon S3 Experts in Hamburg

traigo is VTG's digital rail logistics and fleet management platform. It processes large volumes of telemetry, mileage, geofence, sensor and wagon-movement events in near real time and provides operational services for rail logistics customers across Europe.

As part of Team Customer Selfcare, I worked on the design, implementation, optimisation and operation of large-scale backend services and event-driven processing pipelines — covering both feature development and operational ownership of business-critical production systems. I also regularly acted as first responder for production incidents, data inconsistencies and performance investigations across multiple distributed services.

• Design and implementation of event-driven backend services.
• Migration and replacement of legacy processing pipelines.
• Development of replay / rebuild mechanisms for large event datasets.
• High-throughput asynchronous event processing on SNS / SQS.
• Database and query optimisation for PostgreSQL and DynamoDB.
• Design of scalable read / write models and aggregation pipelines.
• Production troubleshooting and operational support.
• Performance tuning and infrastructure scaling.
• Design and stabilisation of integration and system tests.
• Technical concepts, architecture documentation, and cross-team collaboration.
• Support the further development of existing GitLab CI/CD pipelines

Geofence & Wagon Stay Processing

• Algorithm to detect vehicles within geofences (entry, exit, dwell time).
• Event sourcing with guaranteed chronological order within the affected time window.
• Refactored geofence event and wagon-stay processing logic for performance.
• Resolved race conditions and event-ordering problems in distributed services; server-side filtering, aggregation and optimised query pipelines.
• Repair and replay tooling for corrupted or inconsistent movement data.

Fleet Metadata & Mileage

• Modernised the service; migrated storage from DynamoDB to PostgreSQL to improve traceability and accelerate new features.
• Scalable mileage aggregation and replay mechanisms.
• Read / write models and optimised queries for high-volume mileage calculations.

Sensor & Telematics Integration

• Integrated telemetry and sensor processing pipelines.
• Snapshot and state-calculation logic for sensor systems.
• APIs and persistence models for wagon sensor data; data-quality improvements.
• Further development of a service using gRPC for intra-service communication.

Movement Segment Processing & Routing

• Migrated services to new movement-segment event streams.
• Built replay and rebuild tooling for segment correction.
• Optimised throughput and reliability for high-volume event processing.

Condition Monitoring & Wagon Analytics

• APIs and backend services for wagon condition monitoring.
• Brake-wear prediction processing and wagon analytics functionality.
• PostgreSQL views and optimised query models for operational dashboards.

Operational Reliability - First Responder

• Investigated production incidents and distributed-system failures; DLQ analysis, replay and operational recovery.
• Tuned database performance and AWS infrastructure under production load.
• Improved observability, monitoring and operational tooling.
• Supported rollout strategies, monitoring and post-deployment stabilisation.

• Environment: AWS, Ruby on Rails, GraphQL, React Native
• Penetration test for Backend, Android-App and iOS-App

• Owning RAG, LLM-System, ML-ops-Pipelines for various startups in Insurance, Banking, Energy (KRITIS)

• Poliks – State Police System for information, communication, and case management and other state variants (ViVa, Bravo, customs)
• Developed a test framework for test automation to replace an existing proprietary test client for new developments, focusing on easy maintenance and simple extensibility for new technologies
• Designed the architecture
• Implemented the architecture
• Created a proof of concept by migrating existing test cases into the new test framework
• Platform: C#, .NET, Jira, XRay, Confluence, Playwright, Selenium, UI Automation, Appium, HTML, Git, VMWare, Windows 11, Linux

• Strategic consulting on marketing funds (WKZ) and retail media, focusing on monetization opportunities and data-driven business models
• Conducting a portfolio analysis of existing WKZ measures to assess the revenue and ROI impact of WKZ investments on supplier performance
• Potential analysis of digital WKZ products and initiatives to identify growth and efficiency levers
• Preparing and presenting the results to management and deriving a strategic move-forward plan
• Designing and facilitating several executive workshops to develop a holistic retail media vision and transformation roadmap
• Defining and prioritizing retail media business cases for data-driven evaluation of investment options
• Developing a technical target architecture considering heterogeneous ERP infrastructures and designing an integrated loyalty program
• Designing change management, including impact analysis on organizational structures and processes
• Creating and presenting C-level decision templates
• Establishing a clear retail media governance structure and technical foundation for data-driven marketing
• Developing a roadmap for implementation in 2026

• Further development of a finance layer for subscription and one-time purchase billing and accounting.
• Technologies: Kotlin, AWS (SQS, S3, ElastiCache, Aurora), React, TypeScript, Coroutines, IntelliJ IDEA, Spring (Boot, Data, WebFlux), JUnit, Testcontainers, Cucumber, Liquibase, PostgreSQL, Webservices (REST), R2DBC, OpenAPI 3, Gradle, GIT, Docker, Netty, GitHub Actions, Jira/Confluence, arc42

• Electronic logbook app developed for research centers to maintain their investigations.
• Emphasizes user-driven organization of communication: experiment groups can configure information structure and notifications, while principal investigators maintain full access control.
• Real-time integration with the facility’s metadata catalogue, control system Karabo, and data analysis tool enables the automatic logging of key events, complemented by manual entries as needed.

• Contributed to the development of the Rubix editorial system
• Implemented various microservices based on Java, AWS S3, AWS SQS, AWS SNS, and Spring Boot, deployed to AWS ECS and AWS Fargate
• Designed and developed AWS Lambdas using TypeScript
• Used PostgreSQL in an AWS RDS Aurora cluster and AWS DynamoDB
• Implemented continuous deployment with GitLab pipelines
• Built an Infrastructure as Code environment with AWS CDK
• Set up and maintained a monitoring platform using AWS CloudWatch
• Developed various frontend components with Vue.js
• Designed the microservice architecture applying Domain Driven Design and GraphQL interfaces

• Operation and further development of the inventory system for booksellers (Quimus). It is an in-house development by Libri that is sold to customers as Software as a Service. The software is developed in an agile way by two developer teams (about 5 developers each). The software consists of around 25 Java microservices that mainly communicate via messaging and share a common Angular frontend. The application runs on Kubernetes in AWS.
• Technologies used: Java 17 & 21, Spring Boot 2 & 3, Hibernate, MySQL, Spring Cloud AWS, Lombok, AWS SQS, AWS SNS, AWS RDS, AWS S3, DynamoDB, Kubernetes, Docker, OpenSearch, Hibernate Search, Liquibase, Gradle, Terraform, Helm, GitLab CI, Keycloak OAuth2, TypeScript, Angular
• My focus until December 2023: Connecting additional POS systems to the inventory system. Connecting the data warehouse for report display. Extending existing features (goods receipts, invoicing, item management, ...). Operations and DevOps tasks.
• Focus from January 2024: Extracting the product search from the inventory system into a global service to use in other applications. Integrating the product search into the booksellers' online shops (also run by Libri). Importing and providing digital items in the product search.

• Migration of Oracle databases from on-premise to the AWS Cloud
• Support for technical Oracle solutions and cloud database infrastructures (IaaS and PaaS) RDS vs. EC2, sizing for performance
• Creation and maintenance of DR/HA (Disaster Recovery/High Availability) and backup and recovery policies and procedures (multi-region backup)
• Support for Oracle license selection, Enterprise → Standard migration
• Monitoring database instances
• Implementation and maintenance of database security (wallet, SSL)
• Patch management and version control
• Automated installation and configuration of Oracle databases using Terraform and Ansible

• Languages: PHP7/8 (Shopware 5 & 6), Vue.js, Docker, Oracle, Apache, MongoDB (NoSQL)
• Infrastructure: ScaleCommerce (e-commerce cluster, container-based)
• Team: 3
• Development methodology: Kanban (Jira/Confluence)
• Planning and development of various client projects in an agency environment

• Build data pipelines for raw and curated data layers using AWS S3, Glue, Athena, and Lake Formation
• Establish CI/CD using GitHub Actions or GitLab CI with CodePipeline
• Prototype models into demo APIs packaged with Docker, versioned with Git, added basic tests with pytest, and assist deployments on AWS SageMaker Endpoint
• Perform exploratory data analysis and feature engineering with pandas and PySpark; track experiments in MLflow or Weights and Biases
• Design and execute A/B tests to optimize user engagement and drive data-informed decisions