mqttasync_sendmessage函数作为一个用于发送消息的异步函数,在内部实现上需要考虑建立网络连接、封装MQTT协议格式、保证数据完整性和可靠性、处理错误和超时等方面的问题。通过理解其内部实现原理,我们可以更好地了解该函数在实际应用中的行为和功能,并能够更好地优化和调试相关代码。 3. 理论说明: 3.1 消息传递模型及原...
1. 使用多线程:为了提高发送效率,mqttasync_sendmessage使用了多线程来执行发送任务,避免了阻塞主线程。 2. 消息分片:对于大消息,mqttasync_sendmessage采用了分片技术来减少网络传输的数据量,提高了传输效率。 3. QoS机制:mqttasync_sendmessage支持不同的QoS等级,可以根据需要选择合适的QoS等级来保证消息的送达率。
MQTTAsync_send() : MQTTAsync.h MQTTAsync_sendMessage() : MQTTAsync.h MQTTAsync_setAfterPersistenceRead() : MQTTAsync.h MQTTAsync_setBeforePersistenceWrite() : MQTTAsync.h MQTTAsync_setCallbacks() : MQTTAsync.h MQTTAsync_setConnected() : MQTTAsync.h MQTTAsync_setConnectionLostCallback() :...
I checked MQTTProtocol_keepalive in MQTTProtocolClient.c, when network is OK, this function will send send ping, but when network is not OK, this function will not send ping and not check the ping result, because if (Socket_noPendingWrites(client->net.socket)) { // when network is OK...
qos = 2; MQTTAsync_sendMessage(client, topic.c_str(), &pubmsg, nullptr); } int main() { MQTTAsync client; MQTTAsync_create(&client, "tcp://localhost:1883", "PeriodicPublisher", MQTTCLIENT_PERSISTENCE_NONE, NULL); MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;...
topic, MQTTAsync_responseOptions* response); 785 786 805 DLLExport int MQTTAsync_send(MQTTAsync handle,char*destinationName, int payloadlen, void* payload, int qos, int retained, 806 MQTTAsync_responseOptions* response); 807 808 824 int MQTTAsync_sendMessage(MQTTAsync hand...
the LWT message to the LWT topic on * behalf of the client. This allows otherclients (subscribedto the LWT topic) * to be made aware that the client hasdisconnected. To enable the LWT * function for a specific client, a validpointer to an MQTTAsyncwillOptions * structure...
Jan 22 04:46:26 (none) local4.notice mqtt[407]: MQTT Trace : 3, 20210122 044626.524 (1995869824) (0)< MQTTAsync_isConnected:3646 (1) Jan 22 04:46:26 (none) local4.notice mqtt[407]: MQTT Trace : 3, 20210122 044626.524 (1995869824) (0)> MQTTAsync_sendMessage:4038 ...