resources will be set up to store intermediate results that feed into Service
Composition or complex event processing.
The Service Composition FC resolves services that are composed of IoT
Services and other services in order to create services with extended
functionality. The Functional Component has two main functions: (1) support
flexible service compositions and (2) increase quality of information.
To support flexible service compositions, the Service Composition FC must
provide dynamic resolution of complex services, composed of other services.
These combinable services are chosen based on their availability and the
access rights of the requesting user.
Quality of information can be increased by combining information from several
sources. For example, an average value –with an intrinsically lower uncertainty-
can be calculated based on the information accessed through several
resources.
The Service Choreography FC offers a broker that handles Publish/Subscribe
communication between services. One service can offer it‘s capabilities at the
FC and the broker function makes sure a client interested in the offer will find
the service with the desired capabilities.
Also service consumers can put service requests onto the Choreography FC
while a suitable service is not available at the time when the request was
issued. The service consumer will get notified as soon as a service became
available that fulfils the service request issued before.
4.2.2.4 Virtual Entity
The Virtual Entity FG (see Figure 35 ) contains functions for interacting with the
IoT System on the basis of VEs, as well as functionalities for discovering and
looking up services that can provide information about VEs, or which allow the
interaction with VEs. Furthermore, it contains all the functionality needed for
managing associations, as well as dynamically finding new associations and
monitoring their validity.
The Virtual Entity FG consists of three Functional Components:
VE Resolution; VE & IoT Service Monitoring; VE Service.