7.6 Content-related Semantic Resource Discovery and Semantic Query

This clause describes the functionality supporting content-related semantic resource discovery and semantic query operations, where the SPARQL query statements pertain also to data content stored in <contentInstance> resources. For example:

• A semantic resource discovery with the content constraint: "Return URIs of sensors whose current temperature is greater than 20".
• A semantic query with the content constraint: "Return the locations of sensors whose current temperature is greater than 20".

These examples show that semantic resource discovery and semantic query need semantic representations of actual content which enable a variety of entities in a system, including:

• Semantic-capable data creators who can directly describe its data in a semantic form such as RDF triples;

• Semantic-incapable data creators who only can produce raw data stored as opaque content in the content attribute of the <contentInstance> resource and rely on other entities to add semantic annotations to the raw data;

• Semantic-capable data consumers who have the semantic resource discovery and/or semantic query capability;

• Semantic-incapable data consumers who only can retrieve raw data contents stored in the <contentInstance> resource through pre-configurations.

In order to enable this capability, any information that is originally stored in the content attribute of a <contentInstance> resource can also be represented as RDF triples and stored in certain <semanticDescriptor> resources (see [1] clause 9.6.7 for details). The opaque data in the content attribute of a <contentInstance> supports functionality for semantic-incapable data creators and consumers. The semantic formats are provided to enable semantic-capable data creators and consumers and their semantic functionality.