My contribution: development, testing, documentation.
Nov 2021 - Mar 2022
5 months
Lead Developer
Bayer CropScience
Further development of a mobile application and its backends for farmers. The app calculates amounts and application cycles of fertilizers and fungicides depending on crop types and regions.
Analysis of the existing solution and the backlog.
In the backend: replacing a monolith, implementing microservices.
In the frontend: adjusting the user interface based on product owner requirements.
Implementing a Kafka client.
Expanding unit tests.
Bug fixing.
Handing over the project to a development team, supporting the team, and documentation.
My contribution: architecture, analysis, requirements analysis, testing, documentation, supporting the team in taking over development, leading, coaching.
Jun 2021 - Dec 2021
7 months
Lead Developer
ostermann.de
Project and implementation of an interface (microservice architecture) between the existing inventory management system and a new version of it. The interface had to compare the imported data and create a migration report.
Analysis of the data formats provided by the existing inventory management system as a database table.
Designing the ORM models.
Designing and implementing a converter that imports the data and exports it to the new inventory system.
My contribution: architecture, analysis, configuration, consulting, testing, documentation.
Feb 2020 - Present
5 years 10 months
Internal/private project: smart home with Arduino and Raspberry Pi
Developing a central server and multiple clients for a smart home system.
Used as a sandbox for new technologies: architecture, development, deployment, and testing of clients, servers, and frontends in a heterogeneous environment with event-driven architecture.
My contribution: architecture, requirements analysis, development, testing, TDD, BDD, deployment, maintenance, DevOps, Terraform, Docker, Kubernetes, setting up and maintaining pipelines for testing and roll-out.
Feb 2020 - Sep 2022
2 years 8 months
Hanover, Germany
Lead Developer
Lower Saxony Central Police Directorate
Upgrading a legacy system (managing internal resources, applications, events, data transfer and backup, reports) from PHP 5 to PHP 7.
Static analysis of the codebase. Identifying parts of the code that need refactoring.
Refactoring.
Implementing a new database interface, adjusting external interfaces.
Designing and implementing objects to replace existing logic.
Removing global variables.
Unit tests, integration tests and bug fixing.
Security identification management via a REST API.
Personal contribution: architecture, analysis, requirements analysis, upgrading a legacy system from PHP5 to PHP7, refactoring, tests, TDD (test driven development), middleware implementation, migration, documentation.
Dec 2019 - Jan 2020
2 months
Backend development of a retail platform
aboutyou.com
Analyzing weaknesses in the transaction system, designing countermeasures.
Developing a module to calculate delivery time based on order data, shipping addresses and carriers.
Personal contribution: analysis, refactoring, development, middleware implementation, scrum coaching.
Sep 2018 - Dec 2018
4 months
Development of a retail reward management platform
skon.de
Developing a price and reward calculator that is accessed as a REST server.
Implementing unit tests.
Technologies: PHP7 (PHP7.2), MySQL, JavaScript, Angular, Typescript, Bootstrap, PHPStorm, REST, JSON, XML, OAuth2, SCRUM, Git, Bitbucket, Docker, Kubernetes, an internal framework built on Symfony 4, Twig, PHPDoc.
Personal contribution: analysis, refactoring, development.
Sep 2018 - Nov 2018
3 months
Lead Developer
agrora.market
Developing a platform for agricultural trading. A prototype had to be turned into a live version in a short time. Platform users post their buy/sell offers for agricultural products (grains, oilseeds, etc.). Customers negotiate terms online and close deals.
Architecture and development of the platform, both frontend and backend.
Developing a REST client for exchange server APIs.
Personal contribution: architecture, requirements analysis, refactoring, development, tests, unit tests, UX tests, setting up CI/CD pipelines, scrum coaching.
Sep 2018 - Oct 2018
2 months
Co-development, refactoring and bug fixing of the existing backend system for shop billing
mobilcom-debitel
Migration of the code base from Delphi 5 to Delphi Berlin.
Development of modules for price calculation, inventory calculation and data/database interface synchronization between the central server and individual shops.
My contribution: development, code reviews, analysis, refactoring (from monolith to microservices), legacy code enhancement, tests, unit tests, UX tests, debugging.
Oct 2016 - Aug 2017
11 months
Backend Developer
AirBerlin
Member of a backend developer team. Development, refactoring, optimization of a new version of the booking/tracking system for airports (shopping, booking, payment).
Very intensive use of SCRUM/SAFe.
Development of interfaces to external systems: Amadeus, Comarch, Sixt.
Server-side programming of interfaces for the frontend.
Import/export/recalc of passenger loyalty program cards using batch programming and cron jobs.
Security identification management via a REST API interface.
My contribution: architecture, development, code reviews, analysis, refactoring, legacy code migration, tests, unit tests, performance and load tests, Selenium, debugging, 3rd level support.
Apr 2015 - Sep 2016
1 year 6 months
Lead Developer
rieber.de
Development of an intelligent food flow system according to HACCP rules.
The backend services of the system are accessible through a browser cockpit (for desktop clients) and iOS/Android apps (for mobile clients).
The current version of the cockpit is being refactored with AngularJS using responsive design.
Another group of services are the asynchronous calls to various sensors that report the temperatures of the thermoports (isothermal containers used to transport dishes).
A Symfony controller provides a REST interface.
The data is transmitted in either XML or JSON format.
Frontend adjustments and new features with HTML, CSS, JavaScript.
Co-development of a price comparison platform and a booking portal for long-distance bus travel in an international team (Germany, Brazil, Poland, Turkey).
Reading price lists from various bus companies and operators via their REST and SOAP interfaces.
Development of new features, debugging, code reviews.
My contribution: code reviews, analysis, refactoring, legacy code migration, tests.
Jan 2014 - May 2014
5 months
Karlsruhe, Germany
Backend Developer
Flagbit.de
A billing system for energy supply, electricity and gas market (quantum.de + municipal utilities).
Entering factors relevant to the price lists and reading the price series (prices were determined for specific time ranges – such as months – in 15-minute steps) was done through a REST interface.
The documentation for the interface was created with swagger.io.
Defining reports with YAML scripts, engine in PHP5; graphically mapping the structure of modules, module families and sub-assemblies and the process flows.
Implementation of a PDF generator.
Implementation of a REST client to transfer the generated files to a DMS server (Document Management System).
My contribution: SCRUM member, architecture and implementation of the backend, testing.
Feb 2009 - Mar 2010
1 year 2 months
Workflow system project for a laboratory
Workflow system project for a laboratory conducting tests for the construction industry.
Technologies: OOD, UML.
My contribution: architecture.
Mar 2007 - Mar 2010
3 years 1 month
Szczecin, Poland
Project lead
espol.pl
Collaborated in a team on the project, implementation, and maintenance of a web-based billing system for triple-play services (approx. 20,000 customers).
Generating quotes, contracts, and invoices (Internet, IPTV, VOD, VoIP), importing bank statements, creating configuration files for access servers and access points, report generator, access and shaping control via RADIUS, topology mapping.
My contribution: concept, architecture, implementation, testing, maintenance, project management.
Jan 2006 - Dec 2007
2 years
Consultant
Institute of Paleobiology
Advised on building a database of animal species.
Integrated existing archives and built a new one.
It was essential to create an architecture that ensures the knowledge base stays readable and usable over decades.
This involved a continuous migration feature for new file and database formats.
Technologies: DMS, various file system archives, MediaWiki, migration scripts.
My contribution: concept, architecture, consulting.
Jan 2006 - Dec 2006
1 year
Development of a content management framework based on IIS/ISAPI
Technologies: Delphi, Pascal, IIS.
My contribution: development, testing.
Jan 2006 - Dec 2006
1 year
Szczecin, Poland
Porting the system for general practitioners to PHP5
Ported the general practitioners' system to PHP5: patient registry, calendar backend, digital patient record, report generator.
As part of a reorganization of general practice in Poland, private clinics were established. Previously, the clinics were managed by municipalities.
In my city (Szczecin, population approx. 400,000) I took the archived patient registry from a mainframe, converted it, split it, and stored it in the databases of the new private clinics.
Then came the data cleansing process, partly automated, partly manual.
Development of a 3-layer application for an optical workshop
Project includes: data modeling, implementation of stored procedures in an SQL database, development of the user interface, development of the application server, development of the transfer protocol.
Development of a mail tool for an existing WWW framework under IIS
The tool stores the emails coming from the framework in its own database (Interbase), sends them in mail actions, logs events and creates reports on mail actions (successfully completed, aborted), and searches for repeated emails.
Then development of an admin panel in PHP4 (gaining first experience with web scripting languages like PHP).
Scheduling visits, managing the patient base, digital patient records, diagnoses, medications, creating all necessary documents, reports for health insurance companies.
Development of an innovative editor for the digital patient record based on the WONCA ICPC principle.
The system was developed during this time and installed, rolled out, and maintained in several medical practices.
Own contribution: architecture, implementation, tests.
Jan 1997 - Dec 1998
2 years
Backend part for an online shop
Control of all processes from receiving a customer order, through full inventory management, orders to suppliers, FIFO concept, generating documents such as stock lists, invoices, shipping labels for couriers, delivery notes, etc.
Own contribution: project management, implementation.
Jan 1992 - Dec 1995
4 years
Dortmund, Germany
Developer
Quantum
Development of tool modules (C programming language) for inventory management systems.
Mainly a report generator as an interpretable BASIC-like language for generating report sheets in the existing inventory management system and a management information system.