# DI-CAN Net discover and redundancy

# Application usage of the Net subsystem

The application needs to configure and execute the Net subsystem
 in a defined way to use the discover and redundancy functionality.

@image html images/di_can_net_app_interaction.svg

In the list below the important parts necessary for the application
 are summed:

* @ref can_net_callbacks
* @ref can_net_node_events
* Set the self node role to [FOLLOWER](@ref DI_CAN_NET_NODE_ROLE_FOLLOWER) when ready with
  @ref di\_can\_net\_self\_set\_node\_role.
* Periodic execute @ref di\_can\_net\_execute must be called periodicly from the application
  * Discovers the network (@ref di/can/net/discover.h)
  * Executes the follower/leader statemachine
   * @ref di_can_net_discover_fsm_follower
   * @ref di_can_net_discover_fsm_leader

# Message callbacks {#can_net_callbacks}

The application needs to register a few @ref di_can_callback message callbacks
 or else they are not processed by the Net subsystem. As depicted in the list below:

* @ref DI_CAN_NET_CALLBACK_HEARTBEAT_PUBLISH_ITEM
* @ref DI_CAN_NET_DISCOVER_CALLBACK_REQUEST_ITEM
* @ref DI_CAN_NET_DISCOVER_CALLBACK_REPLY_ITEM

# Register for all node events {#can_net_node_events}

The application is able to register a callback for all events triggered
 from all nodes with @ref di\_can\_net\_node\_set\_event\_callback.

@warning The application should be aware in the callback the Net context is locked!
         And only certian functions may be used or else a deadlock will occur.

All the available events are decribed in the @ref di\_can\_net\_node\_events enum.

Some functions can be used inside the application defined callback:

* @ref di_can_net_node_is_self
* @ref di_can_net_node_is_same_type_as_self