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Golioth Client

The Golioth Client runs in its own thread and handles all communications with the Golioth Cloud. Your program must instantiate and start a Golioth Client, registering callbacks as needed.

Includes

#include <net/golioth/system_client.h>

Including the Golioth System Client header file makes the Golioth API functions available to your program.

Set up the Golioth Client

static struct golioth_client *client = GOLIOTH_SYSTEM_CLIENT_GET();

static K_SEM_DEFINE(connected, 0, 1);

Declare a pointer to a golioth_client struct which will be passed to each API function and instantiate it using the GOLIOTH_SYSTEM_CLIENT_GET() macro.

Here we also define an optional semaphore used to wait for a connection to be established before continuing program flow.

Starting the Golioth Client

Your program must start the Golioth Client by calling the golioth_system_client_start() function. The golioth_client struct created above is a singleton and does not need to be passed to the client start function.

void main(void)
{
client->on_connect = golioth_on_connect;
golioth_system_client_start();

k_sem_take(&connected, K_FOREVER);

while(true) {
;;
}
}

The optional on_connect callback is registered before starting the client.

As noted before, this example uses an optional semaphore that will block program execution until a connection with Golioth is established and the callback function increments the semaphore.

Callback function

It is often useful to run a function each time the Golioth Client connects (or reconnects) to the Golioth Cloud.

static void golioth_on_connect(struct golioth_client *client)
{
k_sem_give(&connected);
}

For this example we give an optional semaphore when a connection is established. Program flow can wait for this semaphore to indicate a connection to Golioth was successfully established.

Register other callbacks when the client connects

In the LightDB Observe part of this guide you'll see the Observe callback is registered inside of this golioth_on_connect callback. This way, "observed" endpoints will be updated each time a connection is established.

Summary

The best example of working with the Golioth Client is found in the Hello sample code.