Semantic modeling with Drupal 8

The focus of the WissKI project was to combine the implementation of the common data storage of the Semantic Web in the form of triples with the functionality of Drupal. An approach like Semantic Mediawiki would be obvious: All individuals correspond to their own websites and all relations correspond to data fields. If one tries to implement this directly with Drupal, individuals in Drupal correspond to entities, concepts to bundles, and relations to fields.

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Due to the strong requirements of ISO 21127 for a complex data graph, WissKI implements an even more complex approach. The integral component of the system is the so-called "Pathbuilder". It supports the system administrator in creating "paths" through ontology. A path is a concatenation of n concepts and n-1 relations between the concepts. When storing data using a path, an individual is first created for each concept. The resulting individuals are then connected to each other by the relations according to the specifications of the path. At the end of such a path in WissKI there is always a relation to a primitive data type in which the actual input is stored. For the storage of several inputs about the same subject paths can be combined in so-called groups. The group defines the common part of all paths belonging to it. The trivial case (groups and paths of length 1) corresponds directly to the implementation of OWL described above. However, it also allows the implementation of more complex models, such as those prescribed by CIDOC CRM. For the implementation in Drupal, the pathbuilder forms an intermediate layer between the triplestore with the data stored there in triples on one side and Drupal with the data storage on the basis of entity types, bundles, entities and fields on the other side. It creates a mapping of groups and subgroups in Pathbuilder to bundles and referenced bundles in Drupal and paths to data fields. This mechanism hides the full complexity of the Semantic Web approach and CIDOC CRM from the actual user, who only has to fill out forms.
The system offers the possibility to load any OWL based ontology. When creating paths based on ontology, the system can assist the administrator by calculating the concepts and relations possible for each step (based on domain and range).