Internet of Things Architecture

Physical Entities, are modelled on this level. Virtual entities and services are
linked together using associations. Services provide access to information
about the corresponding Physical Entities through the resources, to which the
services are associated. The Virtual Entity service specification allows the
specification of the relation between a Virtual Entity and a service. Notice that
the service is part of the association. For example, a room and a temperature
service may be related through the relation (e.g., modelled as an attribute)
indoorTemperature. The association would contain the virtual identifier of the
room, the type of room, the relation indoorTermperature, and the identifier of the
service.

The following use cases are depicted in Figure 131.

 Look up associations for Virtual Entity and Virtual Entity service

specification.

o This use case is initiated by a user of the system, i.e. a hHuman User

or an active digital artefact like a software agent. The user wants to

look up associations that associate the identifier of the Virtual Entity

with a service providing specific information or allowing executing an

actuation affecting the corresponding Physical Entity.

o The assumption is that the user already knows the identifier of the

Virtual Entity.

o In this use case, the Virtual Entity Resolution looks up the

associations corresponding to the identifier and filters them according

to the Virtual Entity service specification. As a result, the user

receives associations containing identifiers of relevant services.

o If the look-up is successful, the user gets the associations containing

the identifiers of the relevant services whose description can then be

looked up through the IoT Service Resolution.

 Subscribe to look-up of Associations based on VE Identifier and VE

Service Specification

o The use case is initiated by a user of the system, i.e., a hHuman User

or an Active Digital Artefact. The user wants to be asynchronously

notified about Associations between the Virtual Entity identified by the

VE Identifier and services fitting the VE Service Specification. A new

notification will be sent whenever a new fitting association becomes

available, is removed or there is a change to an Association that was

previously sent.

o The assumption is that the user already knows the VE Identifier of the

Virtual Entity.

o In this use case, the VE Resolution asynchronously notifies the

subscribing user about fitting Associations and sends a new

notification whenever a new fitting Association has become available,