client.cpp

#include <open62541/client.h>
#include <open62541/client_highlevel.h>
#include <open62541/client_config_default.h>

int main()
{
    /* Create a client and connect */
    UA_Client *client = UA_Client_new();
    UA_ClientConfig_setDefault(UA_Client_getConfig(client));
    UA_StatusCode status = UA_Client_connect(client, "opc.tcp://localhost:4840");
    if (status != UA_STATUSCODE_GOOD) {
        UA_Client_delete(client);
        return status;
    }

    /* Read the value attribute of the node. UA_Client_readValueAttribute is a
     * wrapper for the raw read service available as UA_Client_Service_read. */
    UA_Variant value;/* Variants can hold scalar values and arrays of any type */
    UA_Variant_init(&value);
    status = UA_Client_readValueAttribute(client, UA_NODEID_STRING(1, "the.answer"), &value);
    if (status == UA_STATUSCODE_GOOD &&
        UA_Variant_hasScalarType(&value, &UA_TYPES[UA_TYPES_INT32])) { printf("the value is: %i\n", *static_cast<UA_Int32 *>(value.data)); }

    /* Clean up */
    UA_Variant_clear(&value);
    UA_Client_delete(client);/* Disconnects the client internally */
    return status == UA_STATUSCODE_GOOD ? EXIT_SUCCESS : EXIT_FAILURE;
}