MODDALS guides domain experts and ontology engineers to design the layered structure of reusable and usable ontologies. The output of this process is an informal model with the ontology layers and the knowledge they include at a conceptual level. To define the layered ontology structure, MODDALS applies the main activities and design principles from previous reusable and usable ontology design methodologies.
In contrast to these methodologies, MODDALS takes as reference already implemented ontologies to systematically (1) identify the ontology common and variant domain knowledge and (2) classify it into different abstraction layers. The knowledge of the ontologies developed for specific application types is usually defined through the collaboration between domain experts and application stakeholders, who translate their knowledge into the ontology. In MODDALS, this knowledge is exploited by domain experts and ontology engineers to classify the domain knowledge when designing the layered structure. Therefore, they do not need to analyse the knowledge requirements of different applications and to define and classify the ontology domain knowledge from scratch, facilitating the design of the layered ontology structure.
MODDALS encompasses four main steps. These steps involve the collaboration between domain experts and ontology engineers and are conducted sequentially. In addition, MODDALS takes as reference already developed ontologies to classify the domain knowledge into different abstraction layers. Therefore, before applying the MODDALS steps, a preliminary step is required: analysis and classification of existing ontologies. In this step, domain experts conduct a state of the art of the existing ontologies and the applications they support in the domain concerned. Once the exiting ontologies have been selected and analysed, the methodology itself is implemented
The following are MODDALS steps:
- Step 1: Definition of ontology layers: domain experts define the ontology layers that classify the domain knowledge and the kind of knowledge they include.
- Step 2: Domain knowledge hierarchy creation: both domain experts and ontology engineers collaborate to define the ontology knowledge.
- Step 3: Knowledge classification: ontology engineers classify the knowledge defined in Step 2 into each abstraction layer.
- Step 4: Layer knowledge structuring: The last step is to define how the knowledge of each layer defined in step 1 is structured into ontology modules.
A detailed information about MODDALS can be found at https://innoweb.mondragon.edu/ontologies/MODDALS/resources/description.pdf.