Abstract: The JValue Open Data Service (ODS) is an open source application, founded and developed by the professorship of Open Source Software of the Friedrich Alexander Universität Erlangen Nürnberg (FAU). The application aims to become the go-to place for developers and data scientists around the world when building applications by using Open Data. The JValue ODS’ business model consists of collecting data from various different Open Data APIs, apply processing and cleansing and offering the improved version of the data back to the user. At the time of writing the thesis, the ODS only offers a rudimentary auto generated REST Interface for accessing the resulting data which does not fulfill the various requirements of its targeted user base. Therefore, this thesis aims to offer a solution on how a responsive and clean user API could be implemented using GraphQL as query language. As the ODS itself is a collection of many different docker native micro-services, the relevant functionality for providing the APIs is developed using the same core principles.
In order to grant the user the ability to fetch the raw data, each creation of a new pipeline, which configures the result of the attached data endpoint and a customizable transformation script, can be further configured to generate a read only GraphQL endpoint on the basis of the underlying PostgreSQL schema. This API is capable of filtering and combining all the fields of the collected data. To give the users, who are more knowledgeable in the domain they are working in, the possibility to add business logic to this data a node.js template project is provided. After implementing the desired functionality and hosting it on their preferred hosting solution, the users can register their custom endpoint through the JValue ODS Web Interface which are then validated and merged with the existing schema.
Keywords: GraphQL, JValue ODS, open data
PDF: Bachelor Thesis
Reference: Kai Malte von Rönne. GraphQL-based Generic and Domain Specific Query Interfaces for the JValue ODS. Bachelor Thesis. Friedrich-Alexander-Universität Erlangen-Nürnberg: 2020.