Connection Hooks

C

C

The full example code can be found on our GitHub.

Connection Hooks

Connections hooks are useful for when you want to add additional control to the connection lifecycle in the atSDK. This means you as the developer can implement things like automatically reconnecting when connections drop (example below).

Usage

1. Enable hooks in your context's atserver_connection

Since not every connection uses hooks, you must explicitly enable it.

atclient_connection_hooks_enable(&(atclient->atserver_connection));

2. Write a void* function

Write a function that we would like our atclient connection to run at certain times during the program.

void *pre_write_hook(atclient_connection_hook_params *params)
{
    atlogger_log(TAG, ATLOGGER_LOGGING_LEVEL_INFO, "pre_write_hook called\n");
    return NULL;
}

3. Set the hook

For example, we can set the ATCLIENT_CONNECTION_HOOK_TYPE_PRE_WRITE hook to run our function pre_write_hook before we write any data to our atServer connection.

atclient_connection_hooks_set(&(atclient->atserver_connection), ATCLIENT_CONNECTION_HOOK_TYPE_PRE_WRITE, pre_write_hook))

Examples

Print something before we write to the atServer

The full example code can be found on our GitHub.

#include <atclient/atclient.h>
#include <atclient/atclient_utils.h>
#include <atclient/connection_hooks.h>
#include <atclient/constants.h>
#include <atclient/notify.h>
#include <atlogger/atlogger.h>
#include <stdlib.h>

#define TAG "5a-hooks"

#define ATSIGN "@soccer0"

void *pre_write_hook(atclient_connection_hook_params *params)
{
    atlogger_log(TAG, ATLOGGER_LOGGING_LEVEL_INFO, "pre_write_hook called\n");
    return NULL;
}

int setup_hooks(atclient *atclient)
{
    int exit_code;

    if ((exit_code = atclient_connection_hooks_enable(&(atclient->atserver_connection))) != 0)
    {
        return exit_code;
    }

    if ((exit_code = atclient_connection_hooks_set(&(atclient->atserver_connection), ATCLIENT_CONNECTION_HOOK_TYPE_PRE_WRITE, pre_write_hook)) != 0)
    {
        return exit_code;
    }

    exit_code = 0;
    return exit_code;
}

int main()
{
    int exit_code = -1;

    atlogger_set_logging_level(ATLOGGER_LOGGING_LEVEL_DEBUG);

    char *atserver_host = NULL;
    int atserver_port = 0;

    atclient_atkeys atkeys;
    atclient_atkeys_init(&atkeys);

    atclient atclient1;
    atclient_init(&atclient1);

    atclient_atkey atkey;
    atclient_atkey_init(&atkey);

    atclient_notify_params notify_params;
    atclient_notify_params_init(&notify_params);

    if ((exit_code = atclient_utils_find_atserver_address(ATCLIENT_ATDIRECTORY_PRODUCTION_HOST, ATCLIENT_ATDIRECTORY_PRODUCTION_PORT, ATSIGN, &atserver_host, &atserver_port)) != 0)
    {
        goto exit;
    }

    if ((exit_code = atclient_utils_populate_atkeys_from_homedir(&atkeys, ATSIGN)) != 0)
    {
        goto exit;
    }

    if ((exit_code = atclient_pkam_authenticate(&atclient1, atserver_host, atserver_port, &atkeys, ATSIGN)) != 0)
    {
        goto exit;
    }

    /*
     * Set up hooks so that we can run code before our connection writes to the atServer.
     */
    if ((exit_code = setup_hooks(&atclient1)) != 0)
    {
        goto exit;
    }
    atlogger_log(TAG, ATLOGGER_LOGGING_LEVEL_INFO, "Hooks set up successfully.\n");

    /*
     * Now at this point, it's business as normal.
     * For the sake of this example, we're going to send a notification.
     * Since we set up a pre write hook, it will log a message before we send any data to the atServer.
     */
    if ((exit_code = atclient_atkey_create_shared_key(&atkey, "phone", ATSIGN, "@soccer99", "c_demos")) != 0)
    {
        goto exit;
    }

    if ((exit_code = atclient_notify_params_set_atkey(&notify_params, &atkey)) != 0)
    {
        goto exit;
    }

    const char *value = "Hello! This is a notification!";
    if ((exit_code = atclient_notify_params_set_value(&notify_params, value)) != 0)
    {
        goto exit;
    }

    if ((exit_code = atclient_notify(&atclient1, &notify_params, NULL)) != 0)
    {
        goto exit;
    }

    exit_code = 0;
exit:
{
    free(atserver_host);
    atclient_atkeys_free(&atkeys);
    atclient_free(&atclient1);
    atclient_atkey_free(&atkey);
    atclient_notify_params_free(&notify_params);
    return exit_code;
}
}

Automatically reconnect when the connection drops

// TODO