Group items tagged

SKOS is expressed with Resource Description Framework (RDF), the fundamental language of the Semantic Web.

DITA has a natural fit with SKOS in solutions where DITA topics are classified with subjects that are expressed in SKOS for runtime processing.

Formal subjects are often defined by glossary topics or other topics that already exist within the published information set.

Even if you don't include the subject definitions in your published information, you can use your standard content tools for your subject definitions. For instance, you can author the subject definitions with your XML editor, and archive and version the subject definitions along with your content in your content management or version control system.

Subject classification is as much a part of the information architecture of your content as the navigational organization.

The DITA topic specifies the subject with a specialized section element that includes the following kinds of information:Default labels, including synonyms and denotative imagesNotes on the definition and on the scope of coverage for the subjectListing 1 shows an example of the definition for the Configuring subject:

Because the meaning of a formal topic should never vary based on its use, these fields should be part of the topic.

You can have multiple schemes for the same subjects. For instance, different audiences might be interested in a different subset of the taxonomy.This approach of imposing alternative organizational structures on subjects fits well with the standard use of DITA maps for separating context from content, allowing different organizations to be imposed on the same content. That is, the scheme can be considered a special kind of context for subject definition topics.

Schemes can use non-DITA subject definitions (such as publicly-defined SKOS, OWL, or TopicMaps subjects). You cite the public identifier of the subject with the subjectdef element and identify the subject definition format with the format attribute. This allows you to incorporate publicly-defined subjects into your schemes, or to integrate a formal ontology maintained by your organization with concepts that are specific to your content.

To classify content, another map specialization associates formal subjects with topics (see Figure 4).

Inside the topicref element that references and contains references to the classified content, you nest a topicsubject element to specify the subjects of the content. You can identify a primary subject with the href attribute of the topicsubject element, which also contains subjectref elements for the secondary subjects. If no subject is primary, the topicsubject element should be a container without the href attribute.

In the same way that subject schemes can cite public non-DITA subjects, you can classify DITA content with SKOS, OWL, or TopicMaps subjects by citing the public URI identifiers with the subjectref element and setting the format attribute.

The central circle represents a conceptual topic (such as Security), which:Has a broader relationship to a subject (perhaps System Concerns) within a schemeIs classified by two other subjects (perhaps the Background type and the Novice User role)Contributes to the classification of one topic (such as Web Security)Occupies the second position in a navigation sequence (perhaps under a Glossary heading)

Because subjects are defined by special topics, you can include the subject definition in the content and use it for classification. For instance, the subject topic for Security can both classify content about security and describe security within the Web site or help system content. Figure 5 illustrates this scenario:

Because the classification map is distinct from the scheme map, you can apply multiple schemes to the same classification without requiring changes to the classification. To combine the scheme and classification maps for a deliverable, a higher-level map can refer to both maps using a DITA map reference (see Figure 6).

You might process a single map to generate both an HTML representation of the content and a SKOS representation of the subjects and classification.

On the minus side, HTML content models have evolved well past the internal models that DITA assimilated in 1999, which causes these limitations: Web authors often organize content in patterns that DITA’s content model won’t allow. You can’t always author in DITA “as if it were HTML.” HTML5 has added elements for which there are no equivalent base forms in DITA. Normally, domain specialization in DITA can help rectify this mismatch, but because HTML5 is a “Living Standard” and can add or drop elements as it evolves, an ongoing tension remains between the two formats. Entering values for DITA’s various metadata structures is perhaps harder than it should be for light editing environments.