GONG: an open source Ontology Based System Engineering toolset

System engineers can develop models, requirements, simulations, interfaces and testing tools. This diversity between projects and project phases lead to a variety of engineering tools. Suite of "narrow spectrum" tools and formats lead to irritations when data need to go from one tool to another and from one stakeholder to another.Each of those Model Based System Engineering tools relies on a fixed data model. Thanks to Ernadote’s Onthology Based System Engineering (OBSE), system engineer do not depend anymore on the fixed data model: they are free to develop their own model on top of modeling commercial tool (currently MEGA and Cameo). Agility is key and with Ernadote’s tooling, adding a concept to the ontology takes less than 1 minute. This is useful because since ontology’s model evolve many times over the exploration of the problem space.To go OBSE without MEGA/CAMEO and do simulation, system engineers must go traditional software development: system engineer develops the requirements for a bespoke application and software developers translate the requirements into a full stack application with a conceptual model, a supporting database, controllers and front end. This approach is not suitable when exploring a problem space because, with an "agile" approach, adding a class or an association takes many days / hours even if the application has a lifespan of a few months at best and seldomly deals with large dataset.This paper presents gong, an open source OBSE framework, where adding or refactoring a concept takes less than a minute and whose complexity is low enough to enable a nonprofessional engineer to develop applications. Gong has been used for developing OBSE tools in four real use cases: merging complex data sets, two simulations and a planning tool with complex constraints.