3. State Dynamics View

3.1. Event subscription state

The following model describes the state-behavior of an event subscription from a logical perspective.

Fig. 3.1 State diagram of event subscription state

Table 3.1 States

Name	Description
Not_available	The client and server are not connected. No event subscription or transmission is possible.
Available	The client and server are connected and the event is not subscribed. No event update will be received in this state.
Event_subscribed	The user is subscribed to the event. Event updates will be received in this state. However, the server has not acknowledged the subscription yet. Thus clients do not know if the server will send event updates.

Table 3.2 Triggers

Name	Description
Client_connector::subscribe_event()	The user calls Client_connector::subscribe_event() in order to subscribe to an event.
Client_connector::unsubscribe_event()	The user calls Client_connector::unsubscribe_event() in order to unsubscribe from an event.
Client_connector::Callbacks::on_service_state_change(Service_state::available)	SOCom calls the user callback Client_connector::Callbacks::on_service_state_change(Service_state::available).
Client_connector::Callbacks::on_service_state_change(!Service_state::available)	SOCom calls the user callback Client_connector::Callbacks::on_service_state_change() with a state different from Service_state::available.

3.2. Service state

The following model describes the state-behavior of a service instance as reported to an instance of type Client_connector by callback on_state_change().

Fig. 3.2 State diagram of service state

Table 3.3 States

Name	Description
Service_state::not_available	The service instance does not exist. No provided service instance within the service domain is known.
Service_state::available	The service instance exists, is connected and available. A provided service instance is known, identified and enabled. Thus the service instance can be used and service requests will be answered.

Table 3.4 Triggers

Name	Description
Runtime::make_server_connector()	Construction of Disabled_server_connector by API function Runtime::make_server_connector().
Disabled_server_connector::enable()	Disabling of Enabled_server_connector by API function Enabled_server_connector::disable().
~Disabled_server_connector()	Destruction of Disabled_server_connector().
~Enabled_server_connector()	Destruction of Enabled_server_connector().