@@ -799,12 +799,14 @@ The idea of the approach is to define a general mechanism based on a mapping lan
Figure 7.2-1 shows two oneM2M resource structures, e.g. two \<container\> resources with \<contentInstance\> resources and one \<semanticDescriptor\> resource each. The \<contentInstance\> resources encapsulate information as provided by the source, e.g. a device or IPE. The <semanticDescriptor> resources contain the mapping that describes how the value can be extracted, the value of which NGSI-LD property it represents, to which NGSI-LD Entity the property belongs and what type the Entity has. The resulting information is depicted on right side of Figure 7.2-1 and this information can be accessed through the NGSI-LD API.
The extraction of values is not limited to \<contentInstance\> resources, but includes all resource types that can contain information, e.g. \<flexContainer\> or even \<semanticDescriptor\>.
**Figure 7.2-1: Core Mca and NGSI-LD provide complementary functionality**
Figure 7.2.2 shows an example. The content instances contain values in different formats. On the left side, an integer is contained, in the middle, it is an XML structure.
The semantic descriptor of ResourceA contains mapping information, i.e. that the infomration is about an Entity with the identifer Room123, which is of type Room, has a property called indoorTemperature whose value is to be extracted from the <contentInstance> resource and that has a unit as meta information that indicates that the temperature is given in Celsius. The mapping information in the semantic descriptor of ResourceB indicates that the information belongs to the same entity, but in this case the property is called occupancy and the information has to be extracted from the XML. The extraction examples only serve illustration purposes here, the actual format specifying how to extract information still has to be specified, taking into account suitable existing standards.
Figure 7.2.2 shows an example. The content instances contain values in different formats. On the left side, the content instances under Resource A contain integers, in the middle, under Resource B, the content instances each contain an XML structure.
The semantic descriptor of ResourceA contains mapping information, i.e. that the infomration is about an Entity with the identifer Room123, which is of type Room, has a property called indoorTemperature, whose value is to be extracted from the <contentInstance> resource, and that has a unit as meta information that indicates that the temperature is given in Celsius. The mapping information in the semantic descriptor of ResourceB indicates that the information belongs to the same entity, but in this case the property is called occupancy and the information has to be extracted from the XML. The extraction examples only serve illustration purposes here, the actual format specifying how to extract information still has to be specified, taking into account suitable existing standards.
On the right of Figure 7.2.2 the resulting NGSI-LD entity is represented that can be accessed using the NGSI-LD API.
