This refers to the following ideas:
- The means for devices to expose their capabilities and services
- The means to search for and bind to such services (local and remote)
- The means to exchange events across devices and services
- The means to coordinate the operation of one or more devices
In the context of the Web it seems natural to apply Semantic Web technologies like ontologies for descriptions and rules for reasoning about devices and services. This can exploit servers that act as brokers and which manage access control and trust relationships (see trust models).
For unmanaged services, the control events can be routed peer to peer between the devices involved, see events and protocol bindings. Sometimes it is necessary to manage access to services, e.g. to provide fair use, or to ensure the correct operation of services. In such situations events may be routed through a server that acts as a coordinator.
Rich metadata for devices and services describe the data model, properties and events the service supports. This may go as far as defining how the behavior changes according to which state the device/service is in. Such metadata can play a number of roles
- Finding an appropriate match to a service request
- Determining whether access should be granted
- Enabling high level authoring tools
Ontologies provide a way to describe a device or service in a way that abstracts away for the syntax used to access and process the metadata.
Device coordination may be layered on existing mechanisms, e.g. UPnP.