Channels

Each module declares and defines a channel using zbus macros. For example, in the src/modules/network/network.h file, the Network module declares the network_chan channel:

ZBUS_CHAN_DECLARE(network_chan);

The channel is defined in src/modules/network/network.c:

ZBUS_CHAN_DEFINE(network_chan,          /* Channel name, derived from module name */
         struct network_msg,    /* Message data type */
         NULL,                  /* Optional validator function */
         NULL,                  /* Optional pointer to user data */
         ZBUS_OBSERVERS_EMPTY,  /* Initial observers */
         ZBUS_MSG_INIT(.type = NETWORK_DISCONNECTED)); /* Message initialization */

The fields of the ZBUS_CHAN_DEFINE macro are populated in a similar way across modules:

• Channel name: The name of the channel, derived from the module name.
• Message data type: The data type used to hold message data. The name comes from the channel name.
• Validator function and User data: Not used.
• Initial observers: The initial observer list is empty. Observers are added in the relevant modules later.
• Message initialization: The initial value stored in the channel. Not used, and therefore set either to the module's disconnected message type or to ZBUS_MSG_INIT(0).