The PID Graph in FREYA (additional project report)

This report describes the work done by FREYA work package 2 (WP2) on the PID Graph, one of the pillars of the FREYA project. It summarizes the early work on identifying user stories, describes the decisions about which technical architecture to implement, the work on launching a pre-release version of PID Graph core infrastructure in May 2019 in the form of a GraphQL API, and the work on refining this API until the launch of a production grade version in May 2020. This work has not been reported in detail elsewhere.