Vaadin Experts in Germany

• Further development of the existing e-commerce platform based on SAP Commerce (Hybris) to meet the growing demands of digital commerce.
• Ensuring the scalability and performance of the backend, so the platform remained stable and efficient even under heavy user load.
• Development and integration of new OCC REST APIs and services for modular extensions and flexible adjustments, to implement new features quickly.
• Optimization of data flows and interfaces, which significantly improved platform efficiency and system performance.
• Ensuring a maintainable and scalable code base by using Clean Code principles, proven design patterns, and a future-proof architecture.
• Reduction of errors through extensive testing with JUnit, Mockito, and load tests with Gatling, supported by the introduction of automated test processes.
• Improved system performance through targeted refactoring measures and efficient database queries, especially to handle peak loads.
• Use of modern cloud and monitoring tools such as Kubernetes, Google Cloud Platform (GCP), and Grafana to ensure a stable and monitored infrastructure.
• Clear improvement in efficiency, scalability, and reliability of the platform, which now meets the demands of a dynamic and growing e-commerce market.

• 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)

• Extension of OSGi modules in a complex communication solution
• Debugging communication with Wireshark and remotely in the JENS test environment
• Migration of tests from TestNG to JUnit 5 with Mockito and AssertJ
• Updating vulnerable dependencies and improving code quality
• Changes to the Vaadin frontend
• Increasing test coverage

• Set up GUI test framework for testers and developers to easily create GUI tests
• Implemented automated GUI tests with QF-Test for stock trading software and PDF file comparisons
• Created comparison runs between different versions

Used technologies: QF-Test, Java, Jython

• New development of the vehicle planning and delivery system (FAPS)

• As part of the modernization of a central backend application, the existing monolithic COBOL-based system was replaced by a service-oriented architecture with Spring Boot. The goal of the project is to make the digital mapping of vehicle planning and delivery future-proof and scalable.

• Work on the technical architecture and interface design

• Development of a service based on Spring Boot for migrating existing data into a new data model

• Development of REST APIs and the related service layer

• Development of middleware for integrating the new backend into an existing client

• Creation of unit and end-to-end tests

• Adaptation of build pipelines

• Developer training for customer staff (Java, Azure DevOps, general support)

• Support for testers and other project members

• Upgrade of the Spring Boot version (& Hibernate)

• Creation of documentation

• Java 8 and 17, Spring Boot, Spring JPA, Hibernate, Optimistic Locking (entity versioning), JUnit, Cucumber, PostgreSQL, Azure Cloud, Microservices, Azure Storage, Azure DevOps, Azure Kubernetes Service, RESTful web services, JSON, Scrum, Confluence, ArchUnit

The Helaba ATLAS project aims to modernize core systems and make them future-proof. As part of the subproject, the existing legacy system for international payments is being replaced by a modern web-based application.

• Analysis of functional and technical requirements
• Analysis and optimization of business processes
• Process modeling
• Preparation and facilitation of workshops
• Defining project scope and prioritizing requirements
• Business process management (analysis, modeling, and optimization)
• Specification of user stories
• Designing business and authorization concepts
• Testing and acceptance
• Designing mockups in Figma
• Creating the UI/UX style guide for web applications Approach: Scrum (agile) Technologies: Jira, Confluence, MS Teams, Conceptboard, Java, Vaadin, Figma

• Development of a microservice application for calculating postings on accounts

• Development of backend components with Java or JEE, Quarkus, Kafka, Rest API

• Development of the test component with mocking frameworks (Mockito)

• Development of integration test components

• Creation of OpenAPI specification format

• Configuration of CI/CD pipeline

• Development of frontend components with React

• Design, further development and optimization of system structures

• Code review

• Java Corretto 21, JEE, Quarkus, Golang

• Reactive programming with Spring WebFlux, Project Reactor

• Git, Azure DevOps for CI/CD pipeline, YAML, Json Swagger UI, Postman, Rest OpenAPI, Kafka Streams, Kafka Connect, Log4J

• Microservices, Jira, Confluence, MySQL, Docker, Kubernetes (deployment via Helm charts)

• Spring Security, OAuth 2, JWT, Sonarqube

• IntelliJ, Maven, logging framework Splunk, Agile method Scrum, Nexus, Vaadin V24, build tool Vite

• React, React.JS, Node.js, Jess/JavaScript, Tailwind CSS, Agile method Scrum, accessibility BITV, Playwright

• Develop infrastructure and enhance existing infrastructure: Jenkins, GitLab Pipeline, OpenShift, Docker, Helm Chart, Kubernetes, Artifactory, CodePipeline, CodeArtifact, Python
• Document solutions in Jira/Confluence
• Support other colleagues in various technical areas

• Technology update
• Microsoft Azure certification

• Overall technical responsibility for innovative SAP Customer Checkout solutions at leading clients such as Aramark, Consortium Gastronomie, Feinkost Käfer, TSG Hoffenheim, and VfB Stuttgart. Full support from requirements analysis to implementation and support.

• Successful conception and development of the NDS SmartPOS platform ("Läufer App"):

• Designed the software architecture and implemented it according to Modern Android Development principles.

• Led a small development team (1 Android expert, 1 working student) with a 50% in-house development share.

• Integrated various payment SDKs (S-Payment S-POS, VR Payment, CCV), enabling clients to achieve significant cost savings by reusing existing contracts.

• Successfully rolled out to multiple major clients, resulting in demonstrably increased efficiency of sales staff.

• Independently developed and successfully implemented critical infrastructure components:

• Reporting server (SQL, JasperReports): Measurable reduction in accounting effort by eliminating daily manual transfers into the ERP system.

• ZVT plugin: Solely implemented the serial protocol with Java/Netty over TCP/IP, saving several thousand euros per location and successfully deployed in multiple Bundesliga stadiums.

• Completely in-house development of specialized plugins and server applications for custom functionality extensions of SAP Customer Checkout:

• Waiter Teams Plugin: Allows waiters to work and settle bills in teams.

• SQL reporting: Realized from conception to full documentation independently.

• RFID payment solution for employee cards: Responsible for the complete development cycle.

• Integration with reservation services: Designed seamless connections to Luca and other services, implemented together with a team member.

• Direct technical on-site support for clients, including rapid troubleshooting in real-time environments with high transaction volumes and close coordination with stakeholders to continuously improve the systems based on practical experience.

• Design, development and maintenance of a web application as a policy management system based on a JEE backend and a Vaadin-based UI
• Design and development of interfaces
• Integration of databases
• Design and development of unit and integration tests
• Conceptual coordination with the client
• Technologies and methods: JEE, Vaadin, EJB, Innovator, Hibernate, REST, JMS, SQL, MQ, Maven, Selenium, Arquillian, Mockito, JUnit, Log4j, OOA, OOD, Scrum, Kanban, JavaScript, HTML, CSS, Jenkins, Jenkins Pipelines, Git, GitLab, Subversion, Jira, Confluence, DB2, WebLogic

• Project Livebash (2021-12-01–2023-12-31)

• Development and design of the core system

• Code reviews

• Developer management

• CI/CD

• Client communication

• Leading epics

• Speaking at conferences

• Managing the production system

• Interviewing project developers

• Outcome: production system

• Technologies and tools: Java 11, Java 17, Kotlin, Spring Boot, TeamCity, Gradle, AWS DynamoDB, JUnit, Mockito, Docker, Docker Compose, AWS SQS, AWS EC2, AWS S3, AWS MediaLive, Ethereum, Postman

• Project Robinhood (2024-01-01–2024-05-31)

• Customization and development of product features for specific clients

• Interviews with project developers

• Technologies and tools: Java 17, Java RX, Kotlin, Spring Boot, TeamCity, Gradle, JUnit, Mockito, Docker, Docker Compose, PostgreSQL

• Projects Sway, Tickmill, Pepperstone, UCapital (2024-06-01–present)

• Customization and development of product features for specific clients

• Bug fixes

• Porting tickets from the product

• Feature development

• Technologies and tools: Java 17, Java RX, Kotlin, Spring Boot, TeamCity, Gradle, JUnit, Mockito, Docker, Docker Compose, PostgreSQL

• Visualization, search, and maintenance of various types of master data, providing them via a REST API, and implementing a variety of import and export formats.

• Implementation, architecture, project management.

• Technologies and tools: Angular (Signals, Signal Store, swagger-codegen, standalone components), Java, PostgreSQL, ActiveMQ, JavaScript, Spring Boot (Spring Core, Spring MVC, Spring Data/JPA via Hibernate, Spring Security, Spring Modulith), JUnit, Flyway, QueryDSL, GraphQL, REST API, Node, npm, Maven, SonarQube, GitLab CI/CD pipelines, Docker, Nexus, OpenAPI + Swagger UI, Keycloak, OAuth2, OpenID Connect, IntelliJ IDEA, Jira, Confluence.