Ping Method

Send a PINGREQ message to the gateway to reset the Keep Alive interval and ensure the gateway's liveliness.

Syntax

• C++
• Objective-C
• C

ANSI (Cross Platform)
int Ping();

Unicode (Windows)
INT Ping();

- (void)ping;

#define MID_MQTTSN_PING 8

IPWORKSIOT_EXTERNAL int IPWORKSIOT_CALL IPWorksIoT_MQTTSN_Do(void *lpObj, int methid, int cparam, void *param[], int cbparam[], int64 *lpllVal);

Remarks

The client must send a PINGREQ message using this method during each KeepAliveInterval period. If the client does not send any message to the gateway during this period, it will be considered lost and will disconnect.

The client also uses this message to supervise the liveliness of the gateway to which they are connected. If a client does not receive a PINGRESP from the gateway even after multiple retransmissions of the PINGREQ message, it should first try to connect to another gateway before trying to re-connect to this gateway.

See KeepAliveInterval for more information.

For more detailed requirements regarding Keep Alive intervals and reconnection, refer to the MQTTSN specification.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)