open62541/examples/client_subscription_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. */

/**
 * Client disconnect handling
 * --------------------------
 * This example shows you how to handle a client disconnect, e.g., if the server
 * is shut down while the client is connected. You just need to call connect
 * again and the client will automatically reconnect.
 *
 * This example is very similar to the tutorial_client_firststeps.c. */

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

#include "common.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
handler_currentTimeChanged(UA_Client *client, UA_UInt32 subId, void *subContext,
                           UA_UInt32 monId, void *monContext, UA_DataValue *value) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "currentTime has changed!");
    if(UA_Variant_hasScalarType(&value->value, &UA_TYPES[UA_TYPES_DATETIME])) {
        UA_DateTime raw_date = *(UA_DateTime *) value->value.data;
        UA_DateTimeStruct dts = UA_DateTime_toStruct(raw_date);
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "date is: %02u-%02u-%04u %02u:%02u:%02u.%03u",
                    dts.day, dts.month, dts.year, dts.hour, dts.min, dts.sec, dts.milliSec);
    }
}

static void
deleteSubscriptionCallback(UA_Client *client, UA_UInt32 subscriptionId, void *subscriptionContext) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                "Subscription Id %u was deleted", subscriptionId);
}

static void
subscriptionInactivityCallback (UA_Client *client, UA_UInt32 subId, void *subContext) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "Inactivity for subscription %u", subId);
}

static void
monCallback(UA_Client *client, void *userdata,
            UA_UInt32 requestId, UA_CreateMonitoredItemsResponse *r) {
    if(0 < r->resultsSize && r->results[0].statusCode == UA_STATUSCODE_GOOD) {
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Monitoring UA_NS0ID_SERVER_SERVERSTATUS_CURRENTTIME', id %u",
                    r->results[0].monitoredItemId);
    }
}

static void
createSubscriptionCallback(UA_Client *client, void *userdata,
                           UA_UInt32 requestId, UA_CreateSubscriptionResponse *r) {
    if (r->subscriptionId == 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                     "response->subscriptionId == 0, %u", r->subscriptionId);
    } else if (r->responseHeader.serviceResult != UA_STATUSCODE_GOOD) {
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Create subscription failed, serviceResult %u",
                    r->responseHeader.serviceResult);
    } else {
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
            "Create subscription succeeded, id %u", r->subscriptionId);

        /* Add a MonitoredItem */
        UA_NodeId currentTime =
            UA_NODEID_NUMERIC(0, UA_NS0ID_SERVER_SERVERSTATUS_CURRENTTIME);
        UA_CreateMonitoredItemsRequest req;
        UA_CreateMonitoredItemsRequest_init(&req);
        UA_MonitoredItemCreateRequest monRequest =
            UA_MonitoredItemCreateRequest_default(currentTime);
        req.itemsToCreate = &monRequest;
        req.itemsToCreateSize = 1;
        req.subscriptionId = r->subscriptionId;

        UA_Client_DataChangeNotificationCallback dataChangeNotificationCallback[1] = { handler_currentTimeChanged };
        UA_StatusCode retval =
            UA_Client_MonitoredItems_createDataChanges_async(client, req, NULL,
                                                             dataChangeNotificationCallback, NULL,
                                                             monCallback, NULL, NULL);
        if (retval != UA_STATUSCODE_GOOD)
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                "UA_Client_MonitoredItems_createDataChanges_async ", UA_StatusCode_name(retval));
    }
}

static void
stateCallback(UA_Client *client, UA_SecureChannelState channelState,
              UA_SessionState sessionState, UA_StatusCode recoveryStatus) {
    switch(channelState) {
    case UA_SECURECHANNELSTATE_CLOSED:
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "The client is disconnected");
        break;
    case UA_SECURECHANNELSTATE_HEL_SENT:
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "Waiting for ack");
        break;
    case UA_SECURECHANNELSTATE_OPN_SENT:
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "Waiting for OPN Response");
        break;
    case UA_SECURECHANNELSTATE_OPEN:
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "A SecureChannel to the server is open");
        break;
    default:
        break;
    }

    switch(sessionState) {
    case UA_SESSIONSTATE_ACTIVATED: {
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "A session with the server is activated");
        /* A new session was created. We need to create the subscription. */
        /* Create a subscription */
        UA_CreateSubscriptionRequest request = UA_CreateSubscriptionRequest_default();
        UA_StatusCode retval = 
            UA_Client_Subscriptions_create_async(client, request, NULL, NULL, deleteSubscriptionCallback, 
                                                 createSubscriptionCallback, NULL, NULL);
        if (retval != UA_STATUSCODE_GOOD)
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                "UA_Client_Subscriptions_create_async ", UA_StatusCode_name(retval));
        }
        break;
    case UA_SESSIONSTATE_CLOSED:
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "Session disconnected");
        break;
    default:
        break;
    }
}

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);

    /* Set stateCallback */
    cc->stateCallback = stateCallback;
    cc->subscriptionInactivityCallback = subscriptionInactivityCallback;

    /* 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 */
            sleep_ms(1000);
            continue;
        }

        UA_Client_run_iterate(client, 1000);
    };

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