EObject yourEObject;
DSemanticDiagram d;
Session s = SessionManager.INSTANCE.getSession(yourEObject);

//Then get the container mappings of the diagram and retreive the one you want :

ContainerMapping cm = null
ArrayList<ContainerMapping> al = new ArrayList<> (d.getDescription().getDefaultLayer().getContainerMappings());
		for (ContainerMapping containerMapping : al) {
			if(containerMapping.getName().equals("The name of the mapping of the view you want to create")) {
				cm = containerMapping;
			}
		}

//And then execute the creation of the view :

RecordingCommand cmd = new CreateDDiagramElementCommand(s.getTransactionalEditingDomain(), yourEObject, cm, d);
s.getTransactionalEditingDomain().getCommandStack().execute(cmd);

        DDiagramEditor editor = (DDiagramEditor) EclipseUIUtil.getActiveEditor();
        DSemanticDiagram diagram = (DSemanticDiagram) editor.getRepresentation();
        Session session = SessionManager.INSTANCE.getSession(newRelation);
        
        if (newRelation.getEnds().size() == 2) {
            EdgeMapping mapping = diagram.getDescription().getDefaultLayer().getEdgeMappings().stream()
                    .filter(m -> m.getName().equals("Relation"))
                    .findFirst()
                    .get();
            
            Concept concept1 = newRelation.getEnds().get(0).getRole().getConcept();
            Concept concept2 = newRelation.getEnds().get(1).getRole().getConcept();

            DNodeList source = (DNodeList) getDDiagramElement(concept1, diagram);
            DNodeList target = (DNodeList) getDDiagramElement(concept2, diagram);
            
            RecordingCommand cmd = new CreateDDiagramElementCommand(session.getTransactionalEditingDomain(), newRelation, mapping, source, target);
            session.getTransactionalEditingDomain().getCommandStack().execute(cmd);
        }

    private DDiagramElement getDDiagramElement(EObject obj, DDiagram diagram) {
        return new EObjectQuery(obj)
                .getInverseReferences(ViewpointPackage.Literals.DSEMANTIC_DECORATOR__TARGET)
                .stream()
                .map(el -> (DDiagramElement) el)
                .filter(el -> el.getParentDiagram() == diagram)
                .findFirst()
                .get();
    }