Groovy Experts

Project goal: Carrying out system tests and validating industrial communication and control systems, including requirements definition and verification.

Responsibilities:

• Test planning, test execution
• Test strategy, test cases, and test specifications
• Requirements analysis
• Ensuring traceability between requirements, test cases, and defects
• Carrying out regression and integration tests
• Defect analysis
• Simulation and validation
• NetSniffer Wireshark
• Supporting test automation (Python, CI/CD)
• Reporting
• Stakeholder coordination and agile collaboration (Scrum / SAFe / Kanban)
• V-Model
• CI/CD automation with Python, Groovy, and frameworks (Selenium, PyTest)

Technologies:: CAN, Modbus, Ethernet, PLC, PROFINET, Codebeamer ALM, Scrum, SAFe, MS Teams, Git, CI/CD with GitLab CI and TeamCity, Windows Batch, FAS, Wireshark, Python, Enterprise Architect (EA), AI tools (e.g. ChatGPT, Microsoft Copilot), VS Code, Tia Portal, SCL, Python (Selenium, PyTest)

• Building a data integration platform for high, medium, and low voltage assets for contextual analysis of time series with master data from the SCADA control system (IEC 60870 104), INIS, and SAP.
• Responsibility for the architecture and implementation of the solution, as well as sparring partner for the Product Owner.
• Use of Kotlin, Spring Boot, Maven, TimescaleDB, PostgreSQL, liquibase, Elements IoT, Docker, Kubernetes, Grafana, Python, jupyter, and various API gateways.

• Developed cloud-native enterprise applications on SAP Business Technology Platform using Node.js, SAP UI5, and RESTful APIs, delivering solutions across training management, procurement, employee information, and logistics domains
• Served as the primary developer for the maintenance, enhancement, and production support of three enterprise applications, delivering new features, resolving production issues, and coordinating releases with business stakeholders
• Experienced in leveraging AI-assisted development tools such as Microsoft Copilot to accelerate feature development, generate code, prototype solutions, and support application migration and modernization
• Designed backend services, domain models, and SAP Fiori/UI5 interfaces, implementing business workflows, role-based access control, validations, scheduling, reporting, and data import/export capabilities
• Designed and integrated enterprise services with SAP SuccessFactors, SailPoint, ERP systems, and external Learning Management APIs, including automated synchronization for 11,000+ user data
• Designed and implemented AMQP-based event-driven services processing up to 500 RFID parcel scan events per day for a logistics application
• Managed deployments and application operations using CI/CD pipelines, SAP Solution Manager, SAP BTP Cockpit, Kibana, and cloud monitoring tools, performing root-cause analysis and resolving production incidents
• Managed application dependencies by resolving npm package version conflicts and remediating critical and high-severity security vulnerabilities, ensuring production compliance and application stability
• Collaborated with architects, business users, SAP governance teams, and distributed Agile teams throughout technical design, code reviews, sprint planning, documentation, and software delivery

• Training AI models, evaluating images and text UI/UX, turning the provided data into insights through OpenAI Feather as part of the machine learning workflow

Technologies: OpenAI Feather

• Architected the Yatta Integration Layer – a config-driven integration platform on Java 25, Spring Boot 4 (WebFlux), Temporal, gRPC and Kafka, enabling new third-party integrations (e.g. AVS fulfillment) via declarative JSON configs with zero code changes.
• Designed and implemented Tink integration with 0Auth IBAN verification to enhance fraud prevention and account validation workflows with Adyen payByBank.
• Architected and implemented an OpenFGA-based authorization model for centralized management of users, groups, and fine-grained access control in the vendor portal.
• Architected and led delivery of the Yatta API Gateway platform using GraphQL Federation, providing a unified enterprise API layer across distributed microservices with centralized authentication, authorization and request orchestration.
• Replaced NGINX + NLB with Istio service mesh and AWS ALB; rolled out WAF, OAuth (Cognito), IP whitelisting and RBAC across environments.
• Migrated CDC from Confluent Cloud connectors to a self-hosted Kafka Connect + Debezium stack, reducing operational cost by ~80% across multiple environments.
• Implemented the Transactional Outbox pattern with Debezium for reliable, exactly-once event publishing to Kafka with Avro and Schema Registry.
• Migrated dunning/payment-recovery workflows from Airflow to Temporal, achieving 99.9% reliability for settlement handling.
• Optimised Apache Airflow with deferrable sensors to handle 1000+ concurrent DAG runs without scaling the worker pool.
• Refactored a monolithic Terraform codebase into 3 modular projects, cutting deployment time by ~45%.
• Stood up full observability with OpenTelemetry, Tempo, Prometheus and Loki; automated dev/staging/prod with ArgoCD, Image Updater and Helm.
• Collaborated with product, operations and engineering stakeholders to define scalable platform architecture and integration standards aligned with long-term business and operational goals.

Development and evolutionary further development of a highly available, cloud-native microservice and integration architecture for dealer and retail processes in the Porsche Car Configurator.

Responsibilities

• Development of Java-/Kotlin-based backend, API, and integration components (Spring Boot)
• Integration of internal and external systems via REST/OpenAPI, GraphQL, Apache Kafka, and AWS SQS (synchronous and asynchronous)
• Implementation of stable, high-performance communication and data flows in a cloud-native platform architecture
• Processing of structured data formats (JSON, Protobuf, GraphQL schemas) based on existing API patterns
• Performance optimization of distributed microservices with reduced response times and higher operational stability
• Technical tests (unit, integration, and API tests) as well as error analysis in production-like environments
• AWS Infrastructure as Code with Terraform and AWS CDK
• CI/CD automation (build, test, and deployment pipelines) with GitHub Actions
• AI-supported feature implementation (GitHub Copilot Agent)

Label: Kotlin, Java 25, Spring Boot 4, Protobuf, TypeScript, AWS, Terraform, CDK, Apache Kafka, AWS SQS, REST/OpenAPI, GraphQL, JSON, PostgreSQL, Docker, GitHub Actions, Maven, Gradle, JUnit, Mockito, Testcontainers

• Further development and operation of a central backend service for providing vehicle inventory for international Mercedes-Benz online shops
• Further development of a reservation service for vehicles as part of the checkout process
• Design and implementation of a highly scalable end-to-end test architecture with a focus on maintainability, reusability, and a high number of automated test cases
• Development of a multi-layer test infrastructure with a strict separation of test logic and access layers
• Development of an initialization and caching architecture to significantly speed up local and CI/CD-based test runs
• Development of an AI-supported review architecture for automated evaluation and quality assurance of end-to-end tests
• Development of a dashboard for consolidated display of a vehicle context across multiple backend systems, including AI-generated summaries and compact case analyses
• Integration and further development of connections to various reservation systems via Apache Kafka and REST
• Design of new microservices and support with architecture decisions
• Risk analysis and design of microservice migrations
• Technologies: Java, Spring, Spring Boot, Gradle, Maven, Apache Kafka, REST, OpenAPI, Swagger, Github, Confluence, CI/CD, Microservices, AI, LLMs

• Developing the infrastructure and improving existing infrastructure: Jenkins, Gitlab Pipeline, OpenShift, Docker, Helm Chart, Kubernetes, Artifactory, CodePipeline, CodeArtifact, Python
• Documenting solutions in Jira/Confluence
• Supporting other colleagues in different technical areas

• The goal of BIENE is to provide a uniform program for tax collection for all states.

• In tax collection, the aim is to collect the assessed taxes. This includes handling due dates, documenting incoming and outgoing payments, triggering reminders or refunds. Statute of limitations and payment reminders also play an important role. All payment transactions with banks and accounting are mapped in BIENE.

• Setting up the architecture and coordinating the provisioning of development and test environments at the Hanover location

• Installing and configuring environments on Linux servers (Apache Kafka, PostgreSQL)

• Interface tasks: coordinating and aligning the integration of software products from other departments and their test data

• Upgrading application server, JDK, Maven project structure

• Environment coordination and build management

• Implementing external interfaces

• Implementing business requirements

• Designing and implementing RESTful APIs and OpenAPI specifications

• Designing and implementing microservice architecture

• Setting up and maintaining CI/CD pipelines

• Deploying applications on OpenShift

• Creating technical documentation and diagrams

• Working with SQL databases (Oracle and PostgreSQL)

• Setting up authentication and authorization for the application and users

• Containerizing the application (automated deployment via CI/CD pipeline)

• Developed model-based software for hydrogen tank control units using MATLAB/Simulink, aligned with ISO 26262 functional safety requirements
• Performed system integration and software verification across MIL and HIL environments using dSPACE and Vector tools
• Defined software architecture (SADS) with interface specifications for CAN, analog, and digital communication protocols
• Generated production-ready embedded C code using Simulink Embedded Coder; created and maintained A2L calibration files with CANape
• Designed and executed MIL/HIL test cases ensuring full coverage of functional and safety requirements
• Implemented CODESYS PLC applications on IFM ecomatController; applied CAN and Modbus TCP/IP communication protocols
• Contributed to HMI/UI development using Qt/C++ on Linux (Qt Creator)
• Applied agile Kanban workflow with Git-based version control (Bitbucket)

Tools: MATLAB, Simulink, CANape, CANalyzer, PCAN-View, Embedded Coder, CODESYS, TTC2038/PXROS, Codebeamer, Jira, Git

• Conducting and evaluating web analyses
• Creating and editing tags and scripts in the area of tag management as well as banners and other client-side web elements in the area of consent management
• Technologies used in development: Tealium, JavaScript, IntelliJ, Git, Android Studio, Selenium, Appium, Adobe Analytics, Power Automate, Power App

Project: Tax Exemption Order Application

The client has an existing application for creating and maintaining tax exemption orders for end customers; design and implementation of a comparable application for internal employees.

• Design and implementation of microservices and the UI for the business area "tax exemption orders" using Domain Driven Design as well as Spring Boot and Angular.
• Implementation of reactive, non-reactive, and asynchronous APIs (Spring REST, WebFlux, GraphQL).
• Development of the Angular application, including state management using Signals, RxJS Observables, and subscriptions.
• Securing the API and the application using OAuth2, JWT, and OpenID Connect.
• Configuration and setup of CI/CD pipelines with Jenkins.
• Collaboration with cross-functional teams and conducting code reviews.

Environment: Java, Spring Boot, Angular 18 & 19 (standalone, signals), RxJs, Bootstrap CSS, Vitesting, OpenShift, Istio, microservices, Kafka, Dynatrace, Jenkins, GitLab, Graylog, Sonar, Oauth2, OracleDB

• Developed and deployed microservices in Kotlin and Spring Boot, integrated AWS Secrets Manager to secure credentials and decreased network calls using Spring cache.
• Refactored Kafka consumer using Spring Kafka with semaphore-based backpressure to cap records and keep heap memory stable under spikes; switched to batch upserts to cut down on database invocations; added Testcontainers integration tests for Kafka and database to pave the way for future changes.
• Automated the financial reconciliation workflow in Spring Boot (Kotlin) using Spring Scheduler, transactional boundaries, JPA/Hibernate on MySQL, and Flyway migrations, saving the accounts team 16+ hours per week.
• Designed and dockerized payments end-to-end test framework in Robot (Python) with reusable keyword libraries and profiles; integrated with GitLab CI (JaCoCo XML and HTML reports) to accelerate releases and lift code coverage to 80%.
• Implemented end-to-end observability on Datadog by instrumenting services with Datadog APM, correlating metrics and logs, provisioning dashboards, and creating monitors with burn-rate alerts and anomalies to harden reliability and give stakeholders clear visibility.

• Architected, developed, and maintained scalable backend services using modern Java (17/21), Kotlin, and Spring Boot for high-traffic, performance-critical platforms.
• Served as a technical leader for complex initiatives, taking features from inception through deployment, and implementing runtime validation layers using advanced LLM APIs with secure guardrails.
• Optimized PostgreSQL schemas and query efficiency at scale, drastically reducing data retrieval latencies and ensuring cross-service transactional consistency.
• Spearheaded continuous improvement in development processes, designing comprehensive unit and integration testing frameworks that drove test coverage from 50% to over 90% via JUnit, Spock, and Mockito.
• Partnered extensively with cross-functional product and data squads to define API boundaries, design interfaces, and ensure rapid, high-confidence CI/CD release cycles.