A model defines the basic functionality of a node. A node may include multiple models. A model defines the required states , the messages that act upon those states , and any associated behavior.
A mesh application is specified using a client-server architecture communicating with a publish-subscribe paradigm. Due to the nature of mesh networks and the recognition that the configuration of behavior is performed by a Configuration Client, an application is not defined in a single end-to-end specification such as a profile. Instead, an application is defined in a client model, a server model, and a control model.
This specification defines three types of model: server models, client models, and control models:
• Server model: A server model is composed of one or more states spanning one or more elements. The server model defines a set of mandatory messages that it can transmit or receive, the behavior required of the element when it transmits and receives such messages, and any additional behavior that occurs after messages are transmitted or received.
• Client model: A client model defines a set of messages (both mandatory and optional) that a client uses to request, change, or consume corresponding server states, as defined by a server model. The client model does not have state.
• Control model: A control model may contain client model functionality to communicate with other server models and server model functionality to communicate with other client models. A control model may also contain control logic, which is a set of rules and behaviors that coordinate the interactions between other models that the control model connects to.
Figure 2.5 illustrates how the element-model structure of the device in Figure 2.4 might be implementedin a composite device. The element-model structure of the device is described by the Composition Data that is read by a Configuration Client after provisioning, using the Configuration Server model and the Configuration Client model .
