[paho-dev] MQTTClient or MQTTAsync ?

[rajath ramesh <rajathishere@xxxxxxxxx>]

Hi ,

I was going through samples for asynchronous publication and came across below 2 examples

1. MQTTClient -  http://www.eclipse.org/paho/files/mqttdoc/Cclient/pubasync.html

As per reading adding setCallbacks will make the client asynchronous

2. MQTTAsync - (attaching file - ) I does almost the same except 

while(deliveredtoken != token); ( as in 1 )

Difference between 1 and 2 is waiting for the delivery of the published messaged only ?

I wanted to have clear understanding how 1 and 2 are different.

What are advantages of using MQTTAsync instead of MQTTClient (using setCallbacks) for asynchronous publication.

--
cheerz,
Rajath

/*******************************************************************************
 * Copyright (c) 2012, 2013 IBM Corp.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v1.0 which accompany this distribution. 
 *
 * The Eclipse Public License is available at 
 *   http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Ian Craggs - initial contribution
 *******************************************************************************/

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "MQTTAsync.h"

#if defined(WIN32)
#include "windows.h"
#endif
#define ADDRESS     "tcp://m2m.eclipse.org:1883"
#define CLIENTID    "ExampleClientPub"
#define TOPIC       "MQTT Examples"
#define PAYLOAD     "Hello World!"
#define QOS         1
#define TIMEOUT     10000L

volatile MQTTAsync_token deliveredtoken;

int finished = 0;

void connlost(void *context, char *cause)
{
	MQTTAsync client = (MQTTAsync)context;
	MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
	int rc;

	printf("\nConnection lost\n");
	printf("     cause: %s\n", cause);

	printf("Reconnecting\n");
	conn_opts.keepAliveInterval = 20;
	conn_opts.cleansession = 1;
	if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
	{
		printf("Failed to start connect, return code %d\n", rc);
 		finished = 1;
	}
}


void onDisconnect(void* context, MQTTAsync_successData* response)
{
	printf("Successful disconnection\n");
	finished = 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);

	opts.onSuccess = onDisconnect;
	opts.context = client;

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


void onConnectFailure(void* context, MQTTAsync_failureData* response)
{
	printf("Connect failed, rc %d\n", response ? response->code : 0);
	finished = 1;
}


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

	printf("Successful connection\n");
	
	opts.onSuccess = onSend;
	opts.context = client;

	pubmsg.payload = PAYLOAD;
	pubmsg.payloadlen = strlen(PAYLOAD);
	pubmsg.qos = QOS;
	pubmsg.retained = 0;
	deliveredtoken = 0;

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


int main(int argc, char* argv[])
{
	MQTTAsync client;
	MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
	MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
	//MQTTAsync_token token;
	int rc;

	MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);

	MQTTAsync_setCallbacks(client, NULL, connlost, NULL, NULL);

	conn_opts.keepAliveInterval = 20;
	conn_opts.cleansession = 1;
	conn_opts.onSuccess = onConnect;
	conn_opts.onFailure = onConnectFailure;
	conn_opts.context = client;
	if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
	{
		printf("Failed to start connect, return code %d\n", rc);
		exit(-1);	
	}

	printf("Waiting for publication of %s\n"
         "on topic %s for client with ClientID: %s\n",
         PAYLOAD, TOPIC, CLIENTID);
	while (!finished)
		#if defined(WIN32)
			Sleep(100);
		#else
			usleep(10000L);
		#endif

	MQTTAsync_destroy(&client);
 	return rc;
}