| /* This work is licensed under a Creative Commons CCZero 1.0 Universal License. |
| * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */ |
| |
| /** |
| * Building a Simple Client |
| * ------------------------ |
| * You should already have a basic server from the previous tutorials. open62541 |
| * provides both a server- and clientside API, so creating a client is as easy as |
| * creating a server. Copy the following into a file `myClient.c`: */ |
| |
| #include <open62541/client_config_default.h> |
| #include <open62541/client_highlevel.h> |
| #include <open62541/plugin/log_stdout.h> |
| |
| #include <stdlib.h> |
| |
| int main(void) { |
| UA_Client *client = UA_Client_new(); |
| UA_ClientConfig_setDefault(UA_Client_getConfig(client)); |
| UA_StatusCode retval = UA_Client_connect(client, "opc.tcp://localhost:4840"); |
| if(retval != UA_STATUSCODE_GOOD) { |
| UA_Client_delete(client); |
| return (int)retval; |
| } |
| |
| /* 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); |
| |
| /* NodeId of the variable holding the current time */ |
| const UA_NodeId nodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_SERVER_SERVERSTATUS_CURRENTTIME); |
| retval = UA_Client_readValueAttribute(client, nodeId, &value); |
| |
| if(retval == UA_STATUSCODE_GOOD && |
| UA_Variant_hasScalarType(&value, &UA_TYPES[UA_TYPES_DATETIME])) { |
| UA_DateTime raw_date = *(UA_DateTime *) value.data; |
| UA_DateTimeStruct dts = UA_DateTime_toStruct(raw_date); |
| UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "date is: %u-%u-%u %u:%u:%u.%03u\n", |
| dts.day, dts.month, dts.year, dts.hour, dts.min, dts.sec, dts.milliSec); |
| } |
| |
| /* Clean up */ |
| UA_Variant_clear(&value); |
| UA_Client_delete(client); /* Disconnects the client internally */ |
| return EXIT_SUCCESS; |
| } |
| |
| /** |
| * Compilation is similar to the server example. |
| * |
| * .. code-block:: bash |
| * |
| * $ gcc -std=c99 open62541.c myClient.c -o myClient |
| * |
| * In a MinGW environment, the Winsock library must be added. |
| * |
| * .. code-block:: bash |
| * |
| * $ gcc -std=c99 open62541.c myClient.c -lws2_32 -o myClient.exe |
| * |
| * Further tasks |
| * ^^^^^^^^^^^^^ |
| * |
| * - Try to connect to some other OPC UA server by changing |
| * ``opc.tcp://localhost:4840`` to an appropriate address (remember that the |
| * queried node is contained in any OPC UA server). |
| * |
| * - Try to set the value of the variable node (ns=1,i="the.answer") containing |
| * an ``Int32`` from the example server (which is built in |
| * :doc:`tutorial_server_firststeps`) using "UA_Client_write" function. The |
| * example server needs some more modifications, i.e., changing request types. |
| * The answer can be found in "examples/client.c". */ |