MQTT - Publishing multiple message aynschronously sample to same topic

[testing...@gmail.com]

Hi,

I have put my hands on to MQTT recently and trying samples to achieve my use case.

Use case : Publish messages received from another module in asynchronously as and when it receives to the same topic (something like message will be in queue and client has to read from it).

I have gone through the sample in 'http://www.eclipse.org/paho/files/mqttdoc/Casync/publish.html' and few others as well. When trying to convert this example to handle multiple messages I had few problems on managing the callbacks within loops. Lets say after establishing connection, it calls 'OnConnect' callback where we send message and again it inturn calls another 'OnSend' callback.

Problem is I tried putting a infinite loop in 'OnConnect' and send multiple messages but in that case when will it call 'OnSend' as it lies completely here.

Following is the code snippet

void onConnect(void* context, MQTTAsync_successData* response)
{ 
 MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
 MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
 int rc;

 opts.onSuccess = onSend;
 opts.context = client;
 pubmsg.payload = PAYLOAD;
 pubmsg.payloadlen = strlen(PAYLOAD);

 pubmsg.qos = QOS;
 pubmsg.retained = 0;
 deliveredtoken = 0;

 int count = 0;
 int messageCnt = 10;

 while (count != messageCnt)
 {
  count++;
  std::string message = "Telemetry Data #MSG_";
  std::ostringstream outputString;
  outputString << count;
  message += outputString.str();

  pubmsg.payload = malloc(message.size() + 1);
  strcpy_s((char *)pubmsg.payload, message.size() + 1, message.c_str());
  pubmsg.payloadlen = message.length();

  if ((rc = MQTTAsync_sendMessage(client, TOPIC, &pubmsg, &opts)) != MQTTASYNC_SUCCESS)
  {
   printf("Failed to start sendMessage, return code %d\n", rc);
   exit(-1);
  }
 }
}

void onSend(void* context, MQTTAsync_successData* response)

{

MQTTAsync client = (MQTTAsync)context;

MQTTAsync_disconnectOptions opts = MQTTAsync_disconnectOptions_initializer;

int rc;

printf("Message with token value %d delivery confirmed\n", response->token);

}

OnSend callback never called until this while loop exits and in practical it may be infinite loop so in that case how I will identify the successfully delivered are not

Hence request someone to provide some samples for handling multiple messages publish.

Thanks in advance.

Regards,

Senthamizh Chezhian