A zero-friction collaborative knowledge management tool for complex problem-solving. Developed in-house and cofunded by Townmaking. Uses an entity–attribute–value model approach to capture facts in a loosely defined domain. Uses spatial layout, visual representation and ad-hoc relations to infer meaning and build knowledge. Knowledge can be presented and shared in readable form, referencing the underlying facts.

This effort is the rehabilitation of an earlier knowledge management tool and uses some legacy front-end technology like AngularJS. It is being transitioned to a newer stack that uses Typescript, Modern Javascript and HTMX. The visual aspects are built using the Phaser 3 game engine.

The backend is developed using Scala and the Play Framework.

I am responsible for all cloud infrastructure, development, deployment and monitoring.

Played a key role in building and designing a modern all-in-one shipping service. I worked in close collaboration with C-level operatives, product owners and a senior team of developers to help DHL eCommerce become a market leader.

Being part of the DevOps team, we delivered fast and often using CI/CD, offering many new capabilities to both businesses and consumers. We had a very short feedback loop, with stakeholders having direct access to our teams.

Services were built using a microservices architecture and a variety of technologies, including ZIO, Play Framework, Scala, Scala 3, Akka, Kafka and Cassandra. We applied an event-driven architecture where real-time feedback was required. Event sourcing was used to provide a consistent view of shipment data based on chaotic events.

I was responsible for many services, including:

• Label generation
• Capabilities and product lifecycle management
• Customs
• Customer management
• Printing
• Shipment management

I also contributed to many other services, including:

• Shipment tracking
• Notifications
• Service point applications
• Locker integration
• Customer APIs

We used active monitoring to prevent issues and ensure availability.

RIPEstat is a large-scale information service and the open data platform of the RIPE NCC.

I was responsible for developing data sets to obtain real-time insight in the state of the internet, while also allowing arbitrary time-series. The data is stored using HBase in a large-scale Hadoop cluster.

Responsible for the systems design, architecture, implementation and operations for a collaboration software application with a small team. Using CQRS and event sourcing to maintain a platform-neutral journal with complete history of system interactions based on Akka Persistence, Protobuf and Cassandra. Building real-time projections using Kafka with Akka Streams and best-of-breed technologies. Implemented a front-end based on game mechanics using Typescript, Phaser and AngularJS.

Reimplement the Whois database, adding functionality and fixing long-standing issues. Replacing query, update and near real-time mirroring applications. Building a legacy proxy to support the transition. Implemented using reactive non-blocking IO based on Netty.

Developing a DRM system for a large publisher. Automated functional testing using Geb and Spock. Added new features to the existing application using CQRS and event sourcing with the Axon framework.

I was responsible for single-handily integrating a variety of applications to reliably allow remote monitoring of cardiac arrhythmia by healthcare professionals.

Building a new white-label web portal for Randstad companies for job searchers, employees and HR professionals using JSF, ADF, Oracle Rich Client. Consume and transform services data using Oracle ESB and BPM.

I worked with the solutions division of GX WebManager in Amsterdam to provide consulting to their customers and help them with the implementation of custom functionality and adopting best practices. I helped various clients improving the quality and predictability of their software development processes.

As a lead developer I was responsible for the architecture and implementation of a white label international job site. This job site provided the default option to modernize and unify international Randstad brands and was successfully adopted in multiple countries.

Our agile team delivered new functionality on a weekly basis. We used a domain driven approach. With object relational mapping we managed to implement a rich domain model while keeping database access efficient. One of the key features was job search, where users could define advanced queries and filter down using a multi-faceted search, which was very novel at the time.

Static content and layouts were maintained in a CMS and interwoven with application sections in our back-end.

Holiday portal for searching and booking a diversity of accommodations. I was responsible for the software architecture and implementation to build a white-label application that allowed various accommodation types, like campsites, bungalows and hotels.

Implementing the website and back-office for the Dutch state lottery.

Implementing a new business system to support a new good-driven logistics process.