Robin De Semlyen

– Participated actively in the design of numerous services for the new Galaxy banking repository, from discovery to production: card lifecycle, authorization server, compensation, liquidation, account closure, outgoing banking mobility. – Actively participated in the design of numerous payment services across multiple squads and technical-functional domains, working within agile Scrumban methodology. – Provided direct support for SI architecture work, handling the design or formalization of several structural components. – Realized C4 container diagrams and flow diagrams for several payment services. – Identified, diagrammed, and implemented a Hexagonal Architecture. – Harmonized back-end architecture practices (evolution of common libraries and documentation, sharing Kafka Streams experience). – Implemented Kafka Stream services from scratch using joins, state stores, windowing, and custom processors. – Created and configured topics, and optimized Kafka clients based on technical-functional constraints. – Implemented exactly-once delivery guarantees and inbox & outbox patterns. – Kafka Streams: Implemented services using joins, multi-source aggregators, filtering, flagging, and windowing. – Kafka Connect: Configured Source and Sink JDBC connectors, classic and custom SMTs (Single Message Transformations). – Achieved complete and automated test coverage for the application, encompassing all distributed services (input and output topics, mock API, database, and GCS buckets) via JUnit and Cucumber. – Conception and implementation of numerous payment services enabling decoupling and resumption of card repository governance. – Seamless deployment of new card repository topics without service interruption. – Realization of a part of the SI architecture validated by Bforbank's Technical Directorate. – Presented and demonstrated results to the Galaxy program teams and relevant business teams (Engineering All-Hands).

– Contributed to the stabilization, security, and evolution of the group's transactional communication service, ensuring reliable and high-performance delivery of millions of daily messages globally. – Operated in an international context with communication entirely in English, within a team distributed between France and the Netherlands. – Actively participated in the technical and functional refinement of tickets, proposing and challenging solutions with a focus on achieving the most technically satisfying and cost-effective outcomes. – Achieved significant code coverage and security vulnerability reduction, increasing test coverage from 35% to 80% and removing over 500 critical security flaws. – Improved code quality and sustainability: Drastically reduced cyclomatic complexity, performed decoupling and extractions, applied SOLID principles and various design patterns (Validator, Matching, Template Method, Facade, Builder, Singleton). – Reorganized micro-services: Merged and eliminated micro-services, and standardized technologies used. – Created a common development environment to improve experience and speed through standardized setup via containerized and shared images. – Migrated to a more resilient message broker familiar to Decathlon Ops (ActiveMQ to Kafka). Added retry systems, circuit breakers, and provider fallbacks for high availability and resilience. – Developed a comprehensive observability service to track the lifecycle of communications and their performance indicators (webhooks, creation and export of tech and business metrics to Datadog). – Optimized performance through asynchronous multi-threaded parallelization of long and repetitive tasks. – Implemented multi-provider intelligence to optimize availability and cost, adding new Email and SMS providers, and new channels like Push Notification and Salesforce Journey Builder. – Enhanced UX by refining error handling, API feedback, adding features, and improving the back-office. – Led the final rush for the Olympic Games successfully without incident; conducted load tests and delivered functionalities ensuring resilience for the Olympics, as Decathlon was a main partner. – Increased user satisfaction and number of users, reducing RUN support allocation from 3 days/week to 0.5 days/week. – Presented and demonstrated results during three All Hands Engineering sessions, in English, to 200 engineers and business unit directors. – Conducted regular on-call duties for the project.

– Responsible for the white-label mobile application, designed and implemented critical user journeys from scratch, including a secure onboarding process (account creation, activation, KYC) and strong authentication mechanisms for sensitive functionalities. – Worked daily with the entire fintech team (3 backend developers, CTO, PM, Designer, Legal, and CEO), collaborating occasionally with Takima's React expert, following a rigorous agile methodology with two-week sprints. – Established the application's structure and flows (navigation, redirections, restrictions, and blocking state management). – Optimized performance using React Context, React Cache, and Tanstack Query. – Improved user experience with skeletons, loading states, and degraded modes. – Managed the deployment of various white-label LinkCy applications to production (App Store) and testing environments (TestFlight). – Onboarded new team members and provided daily technical support. – Contributed to the main API (Partner API), expanding full-stack engineering skills. – Successfully secured the mission for Takima through a convincing initial Proof of Concept (PoC) within a tight deadline. – Completed full development of a white-label BaaS mobile application, deployed in production and pre-production (TestFlight/Google Store) in 10 different versions. – Designed and implemented critical onboarding journeys (SCA, KYC, KYB) in compliance with banking regulations. – Ensured smooth onboarding and project handover.

– Participated in the Takima Master 3 training, understanding the importance of a solid transverse technical foundation, best practices, and mastering key market tools and frameworks. – Completed an demanding 9-week training structured around 13 milestones, focusing on full-stack marketplace development. – Covered Dev/DevOps topics: Git, TDD, Docker, Docker-compose, Gitlab CI/CD, Unit Tests. – Covered Backend Development: Java, Maven, REST, Spring, Spring MVC, Spring Data, Spring Boot, Hibernate, JPA, PostgreSQL, Flyway. – Covered Frontend Development: EcmaScript, React, Angular, bundlers. – Attended Master Classes on advanced web application architecture themes (databases, application servers, container orchestrators, security, various architecture types, performance). – Developed and deployed an 'amazon-like' REST API (marketplace) from scratch. – Implemented a CI/CD flow to pre-production and production environments. – Developed a Frontend SPA application based on the marketplace API. – Learned and applied software development best practices (SOLID, Clean code, TDD).