a sample of my work

I develop solutions using python, web and graph technologies. I created more than 50 projects as work contracts, being responsible to deliver a fully working final product. I also work as a freelancer, where I help organisations in various roles.

If you need help with your project, you can contact me.


Projects I work on now or have worked on in the recent past.

Commercial projects

Gothaer Systems (via jobactive) needed a prototype (PoC) for a metadata management system in a graph database. I developed the prototype, unifying data from different sources and providing a unified data model. The prototype was made using python, flask, neo4j and htmx, basically my preferred web stack.

Univention (via abcona), is the creator of the Univention Corporate Server (UCS), a linux based operating system. UCS has a strong focus on integrated identity management. This is also used to manage schools and school environments. Within this subproject UCS@school I consult on the architecture of new components, security aspects, and implementation.

Bundesagentur für Arbeit (via Tria Consulting). The german Federal Employment Office runs a knowledge management system based on plone within its IT-Team. My task there is to do general consulting on knowledge management, implementation of ideas and improvements, and overview of the system.

Deutsche Bahn DB Systel GmbH (via Hays). Planning and implementation of an enterprise wide information management system. I was involved in lots of areas in those 2.5 years: requirements gathering, cost calculation, architecture, data models, security, entity resolution, crypto, simulation, graph databases and technologies, neo4j, exchange with scientists, general research, and last, but not least, implementation of PoCs.

www.westaflex.com is one of the projects I have been working on with yhun, and is also one of my oldest. My involved with this wonderful customer has been in creating all technical aspects from their very first web page up to the current state, including content management systems, shopping systems, on-the-fly pdf customisation, a semantic-web like and lately, a redo of the website using plone. Right now we are deploying a custom intranet system with a specific emphasis on knowledge management. Ongoing for more than 20 years.

Open source projects

zeitsiegel is a website around the idea that one can show the existence of information using a hash and a bank transfer. This can be used for IP protection, but also to show that knowledge existed before a nda was signed.

GraphUI is a web application for editing property graphs. At the moment it supports neo4j as a backend, but other backends will follow. It also has some conventions that allow semantic graph editing.

auditd-tools is a small python utility around auditd events, which allows handling of those events for purposes like fulltext search.

opencoin.org is about creating virtual cash. This means electronic payments, for small amounts and anonymous transfers. Pretty much like real cash, just electronically.

Older projects

noscenda.de is a standalone product for knowledge management. Its purpose is to allow members of an organization to share information, files, create appointments and have simple group chat functionality. The system is based on plone.

openideo is a website for global collaboration on (social) challenges, developed by the people at ideo. People can put up inspirations, share concepts and evaluate them together. My involvement is to help with technical aspects of the backend, using the bfg/pyramid framework. (via largeblue)

wikipedia needed an extension for mediawiki, the software behind wikipedia, to allow the flagging of some pages as being 'stable'. The purpose is to reduce vandalism. The extension is finished, it’s now live on the german wikipedia site. My role was seeding the development, and interfacing with the non-tech people. I wrote the first approach in PHP, but luckily very knowledgeable members of the community stepped in and took on most of the development work (thanks especially to VoiceOfAll). Ah, the power of open source.

unicef (via the hub) are getting a knowledge management system for one of their subprojects for emergency workers around the globe. The main focus is usability and user-awareness-of-each other. The system is developed using Zope, and within the time I work together with Tom on designing the backend architecture and implementing it, but also helping the UI people to get the functionality into the front end.

samsung experience via imagination is Samsung's flagship store in new york. Beyond their technology gems you can also use a couple of kiosk terminals to get information, book tours etc. These terminals use a custom CMS on the backend side. This CMS is used for providing new content to the terminals, taking requests and information from them and allowing administration of everything. This CMS is developed from scratch by me, using PHP.

directionless enquiries is a community callcenter. The idea is to have the community equivalent of a directory service, a place where you can call in to have your question about directions, locations or topics answered by a volunteer. The volunteers are connected using VoIP. The project is in the early development state, with me being responsible for the asterisk server, which is managing all the phones and voip issues, and also provides conferencing. This is in partnership with The People Speak, who besides being great people, are also the originators of the concept. Open Source.

copycan is about creating a model for an alternative compensation system for content producers. Content these days only knows two states it can be copied, or it can't. Once the first copy is out, all the copies are out. Digital content is not a scarce resource. Following the example of blender, we are looking into establishing an escrow service which allows producers to collect money for their work before they open it to the public.

yhun is where you can find most of the work I did with Frank Linnenschmidt. He is my designer of choice, and I am fortunate enough to have worked with him for nearly ten years now. This is the place to look for most of my past projects. The portfolio there is full of references to projects, where I have done all the technical work. This involved lots of php, mysql, apache, but lately mostly python, zope and plone

dissconnected.net is a community website, build on plone. The goal of this project are 'active sustainable communities'. Based on plone we create a system that helps citizens to become more active members of their community. The system will help organizing groups, activities, events, mailing lists, local trade, allows use of alternative currencies etc. My role is in the conceptual and technical development. Open Source.

cts is a community trading system, with a strong support for alternative/new money. It allows people to trade their goods and services in the currencies that groups in the system have set up. The project is open source, sponsored by The Open University and done in cooperation with the Open Coop. Within the team of people I am mainly responsible for the work on the zope backend.

www.findmybook.de is a metasearch engine. If you query for a book title, up to 30 databases are queried in parallel and real time to deliver the best (and hopefully cheapest) results to you. The whole technical backend is designed and developed by me. Lots of php involved, with a strong emphasis on screen scraping and a custom system for the parallel query processing.

mute is a great magazine, based in London, running in paper form for many years now, and in the transition to a print on demand version. Together with kpi I am helping with the process, which involves lots of coding work on drupal related stuff. Security, taxonomy, navigational structure and general php work, but finally also work on the pdf creation.

www.gfu.net is a training company, based in Cologne, catering the needs of larger corporations and governmental organisations. I worked there as a trainer for PHP, Apache and MySQL, but also for HTML, Javascript and CSS.