Sebastian Wahn - Backend Engineer

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Gemmrigheim, Germany

Experience

Jun 2023 - Feb 2024

9 months

Part of the development and maintenance of a NodeJS-based backend application delivering Key Performance Indicator (KPI) information to clients.
The application extracts KPIs from the database, refines and aggregates them within the system.
Enabled authenticated frontend applications to request data via REST and display responses through intuitive diagrams and charts.
Established a robust unit and integration tests pipeline.
Conducted strategic refactoring to enhance testability and simplify the system in adherence to the KISS principle.
Implemented new features in an agile environment.

Sep 2021 - Mar 2023

1 year 7 months

Developed and maintained a Vehicle Information System importing streaming vehicle data via Kafka and refining it via business logic to avoid persisting unnecessary data.
Sent refined datasets to a third-party application which created vehicle images and saved them back into the system.
Developed a new streaming integration from Kafka to replace the previous long polling solution.
Addressed technical challenges of persisting streaming data without flooding the third-party application due to faster consumption and slower image processing.

Jan 2021 - Sep 2021

9 months

Developed an Online Car Configurator allowing users to customize a vehicle via a web frontend with real-time visualization.
Designed and developed microservices in NodeJS/TypeScript using the NestJS framework.
Implemented a rule engine to determine the validity of user-provided options based on configurable rules written in Boolean algebra from a third-party application.
Imported and evaluated the third-party application’s rule set within the rule engine to validate or invalidate configurations.

Jan 2020 - Present

6 years 1 month

Developed a website and backend service to manage HDRi backgrounds, enabling access to an asset library with search, purchase, and download functionality.
Built a cloud-native platform in AWS using Lambda functions for all functionality.
Implemented an import pipeline to move, rename, and process asset files, extract keywords from EXIF/IPTC metadata, generate thumbnails, and create entries in DynamoDB.
Implemented subscription handling via the Stripe API and consumed events to handle error cases and ensure reliability.

Aug 2019 - Dec 2019

5 months

Conducted business process analysis to identify missing but required information in tooling and interdepartmental communications.
Created detailed business process descriptions using BPM diagrams.

Jul 2016 - Jun 2019

3 years

Architected and developed a cloud-native platform to generate high-quality imagery in the web browser using pre-generated 3D assets and VRay rendering in AWS.
Implemented web sockets to stream preview images to users’ browsers.
Utilized AWS application load balancers and EC2 instances with on-demand scaling to handle variable user load.
Batched high-quality image generation in a queue processed by dynamic EC2 instance pools.

Nov 2015 - Jun 2016

8 months

Developed REST microservices in NodeJS for a vehicle inventory system to display vehicle counts and metadata for site administrators.
Integrated external APIs and implemented webhooks for external consumers.

Oct 2013 - Oct 2015

2 years 1 month

Developed and maintained PHP-based e-commerce applications.
Created a product information management system in C# with REST APIs and an AngularJS frontend.
Developed a newsletter layout tool using NodeJS and Electron, enabling users to set up newsletters by dragging and dropping UI components.