client_connect_loop.c 3.2 KB

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  1. /* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
  2. * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
  3. /**
  4. * Client disconnect handling
  5. * --------------------------
  6. * This example shows you how to handle a client disconnect, e.g., if the server
  7. * is shut down while the client is connected. You just need to call connect
  8. * again and the client will automatically reconnect.
  9. *
  10. * This example is very similar to the tutorial_client_firststeps.c. */
  11. #include "open62541.h"
  12. #include <signal.h>
  13. UA_Boolean running = true;
  14. UA_Logger logger = UA_Log_Stdout;
  15. static void stopHandler(int sign) {
  16. UA_LOG_INFO(logger, UA_LOGCATEGORY_CLIENT, "Received Ctrl-C");
  17. running = 0;
  18. }
  19. int main(void) {
  20. signal(SIGINT, stopHandler); /* catches ctrl-c */
  21. UA_ClientConfig config = UA_ClientConfig_default;
  22. /* default timeout is 5 seconds. Set it to 1 second here for demo */
  23. config.timeout = 1000;
  24. UA_Client *client = UA_Client_new(config);
  25. /* Read the value attribute of the node. UA_Client_readValueAttribute is a
  26. * wrapper for the raw read service available as UA_Client_Service_read. */
  27. UA_Variant value; /* Variants can hold scalar values and arrays of any type */
  28. UA_Variant_init(&value);
  29. /* Endless loop reading the server time */
  30. while(running) {
  31. /* if already connected, this will return GOOD and do nothing */
  32. /* if the connection is closed/errored, the connection will be reset and then reconnected */
  33. /* Alternatively you can also use UA_Client_getState to get the current state */
  34. UA_StatusCode retval = UA_Client_connect(client, "opc.tcp://localhost:4840");
  35. if(retval != UA_STATUSCODE_GOOD) {
  36. UA_LOG_ERROR(logger, UA_LOGCATEGORY_CLIENT, "Not connected. Retrying to connect in 1 second");
  37. /* The connect may timeout after 1 second (see above) or it may fail immediately on network errors */
  38. /* E.g. name resolution errors or unreachable network. Thus there should be a small sleep here */
  39. UA_sleep_ms(1000);
  40. continue;
  41. }
  42. /* NodeId of the variable holding the current time */
  43. const UA_NodeId nodeId =
  44. UA_NODEID_NUMERIC(0, UA_NS0ID_SERVER_SERVERSTATUS_CURRENTTIME);
  45. retval = UA_Client_readValueAttribute(client, nodeId, &value);
  46. if(retval == UA_STATUSCODE_BADCONNECTIONCLOSED) {
  47. UA_LOG_ERROR(logger, UA_LOGCATEGORY_CLIENT, "Connection was closed. Reconnecting ...");
  48. continue;
  49. }
  50. if(retval == UA_STATUSCODE_GOOD &&
  51. UA_Variant_hasScalarType(&value, &UA_TYPES[UA_TYPES_DATETIME])) {
  52. UA_DateTime raw_date = *(UA_DateTime *) value.data;
  53. UA_DateTimeStruct dts = UA_DateTime_toStruct(raw_date);
  54. UA_LOG_INFO(logger, UA_LOGCATEGORY_USERLAND, "date is: %02u-%02u-%04u %02u:%02u:%02u.%03u",
  55. dts.day, dts.month, dts.year, dts.hour, dts.min, dts.sec, dts.milliSec);
  56. }
  57. UA_Variant_deleteMembers(&value);
  58. UA_sleep_ms(1000);
  59. };
  60. /* Clean up */
  61. UA_Variant_deleteMembers(&value);
  62. UA_Client_delete(client); /* Disconnects the client internally */
  63. return UA_STATUSCODE_GOOD;
  64. }