client_connectivitycheck_loop.c

/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
 * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */

#include <open62541/client.h>
#include <open62541/client_config_default.h>
#include <open62541/plugin/log_stdout.h>

#include <signal.h>
#include <stdlib.h>

UA_Boolean running = true;

static void stopHandler(int sign) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "Received Ctrl-C");
    running = 0;
}

static void
inactivityCallback (UA_Client *client) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "Server Inactivity");
}

int main(void) {
    signal(SIGINT, stopHandler); /* catches ctrl-c */

    UA_Client *client = UA_Client_new();
    UA_ClientConfig *cc = UA_Client_getConfig(client);
    UA_ClientConfig_setDefault(cc);

    cc->inactivityCallback = inactivityCallback; /* Set stateCallback */
    cc->connectivityCheckInterval = 2000; /* Perform a connectivity check every 2 seconds */

    /* Endless loop runAsync */
    while (running) {
        /* if already connected, this will return GOOD and do nothing */
        /* if the connection is closed/errored, the connection will be reset and then reconnected */
        /* Alternatively you can also use UA_Client_getState to get the current state */
        UA_StatusCode retval = UA_Client_connect(client, "opc.tcp://localhost:4840");
        if(retval != UA_STATUSCODE_GOOD) {
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                         "Not connected. Retrying to connect in 1 second");
            /* The connect may timeout after 1 second (see above) or it may fail immediately on network errors */
            /* E.g. name resolution errors or unreachable network. Thus there should be a small sleep here */
            UA_sleep_ms(1000);
            continue;
        }

        UA_Client_run_iterate(client, 1000);
    };

    /* Clean up */
    UA_Client_delete(client); /* Disconnects the client internally */
    return EXIT_SUCCESS;
}