Client is not subcribing in Paho C

[shakti gupta]

Hi,

     I am beginner in MQTT. i am using eclipse paho C. i am facing some problem in a sample program. Please have a look into code. i have pasted code and output of publisher and subscriber below. In subscriber, it show some corrupted string and then it lost connection. Please help me to find mistake.

sample_publisher.c

#include "stdio.h"

#include "stdlib.h"

#include "string.h"

#include "MQTTClient.h"

#define ADDRESS    "tcp://m2m.eclipse.org:1883"

#define CLIENTID    "ExampleClientPub"

#define TOPIC       "MQTT Examples"

#define PAYLOAD     "Hellooooooo"

#define QOS         1

#define TIMEOUT     10000L

int main(int argc, char* argv[])

{

    MQTTClient client;

    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;

    MQTTClient_message pubmsg = MQTTClient_message_initializer;

    MQTTClient_deliveryToken token;

    int rc;

    int status;

    char* str="HELLO";

    MQTTClient_create(&client, ADDRESS, CLIENTID,

        MQTTCLIENT_PERSISTENCE_NONE, NULL);

    conn_opts.keepAliveInterval = 20;

    conn_opts.cleansession = 1;

    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)

    {

        printf("Failed to connect, return code %d\n", rc);

        exit(-1);

    }

    pubmsg.payload = (void*)str;

    pubmsg.payloadlen = strlen(str);

    pubmsg.qos = QOS;

    pubmsg.retained = 0;

    printf("lenght is %d", pubmsg.payloadlen);

    status=MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token);

    printf("status is %d \n",status);

    printf("Waiting for up to %d seconds for publication of %s\n"

            "on topic %s for client with ClientID: %s\n",

            (int)(TIMEOUT/1000), PAYLOAD, TOPIC, CLIENTID);

    rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);

    printf("Message with delivery token %d delivered\n", token);

    MQTTClient_disconnect(client, 10000);

    MQTTClient_destroy(&client);

    return rc;

}

Output of Sample_publish

./sample_publish 

lenght is 5status is 0 

Waiting for up to 10 seconds for publication of Hellooooooo

on topic MQTT Examples for client with ClientID: ExampleClientPub

Message with delivery token 1 delivered

Sample_subscribe.c

/*

 * sample_subscribe.c

 *

 *  Created on: 22-Sep-2016

 *      Author: shakti

 */

#include "stdio.h"

#include "stdlib.h"

#include "string.h"

#include "MQTTClient.h"

#include "sample_subscribe.h"

#define ADDRESS    "tcp://m2m.eclipse.org:1883"

#define CLIENTID    "ExampleClientPub"

#define TOPIC       "MQTT Examples"

#define PAYLOAD     "Hellooooooo"

#define QOS         1

#define TIMEOUT     10000L

int main(int argc, char* argv[])

{

MQTTClient client;

MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;

int rc;

int ch;

//a. Create an instance of MQTT client

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

//b. Prepare connection options

conn_opts.keepAliveInterval = 20;

conn_opts.cleansession = 1;

MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered);

//c. Connect to broker with the connection options

if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)

{

printf("Failed to connect, return code %d\n", rc);

exit(-1);

}

//d. Subscribe interested topics.

printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n"

"Press Q<Enter> to quit\n\n", TOPIC, CLIENTID, QOS);

MQTTClient_subscribe(client, TOPIC, QOS);

do

{

ch = getchar();

} while(ch!='Q' && ch != 'q');

//MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered);

//e. Disconnect to broker

MQTTClient_disconnect(client, 10000);

//f. Release resources

MQTTClient_destroy(&client);

return rc;

}

Sample_subscribe.h

#ifndef SAMPLES_SAMPLE_SUBSCRIBE_H_

#define SAMPLES_SAMPLE_SUBSCRIBE_H_

volatile MQTTClient_deliveryToken deliveredtoken;

void delivered(void *context, MQTTClient_deliveryToken dt)

{

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

deliveredtoken = dt;

}

int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message* message)

{

int i;

char* payloadptr;

printf("Message arrived\n");

printf(" topic: %s\n", topicName);

printf(" message: ");

printf("address of message is %u \n",message);

payloadptr = (char*)message->payload;

printf("11111 \n");

printf("message is.... %s",payloadptr);

for(i=0; i<message->payloadlen; i++)

{

printf("2222 \n");

putchar(*payloadptr++);

printf("33333 \n");

}

putchar('\n');

if(message!=NULL)

{

printf("555 \n");

MQTTClient_freeMessage(&message);

printf("666 \n");

}

//free(topicName);

printf("4444 \n");

return 1;

}

void connlost(void *context, char *cause)

{

printf("\nConnection lost\n");

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

}

#endif /* SAMPLES_SAMPLE_SUBSCRIBE_H_ */

Output of sample_subscribe

./sample_subscribe 

Subscribing to topic MQTT Examples

for client ExampleClientPub using QoS1

Press Q<Enter> to quit

Message arrived

 topic: MQTT Examples

 message: address of message is 2281704372 

11111 

message is.... crashedket.c2222 

c33333 

2222 

r33333 

2222 

a33333 

2222 

s33333 

2222 

h33333 

2222 

e33333 

2222 

d33333 

555 

666 

4444 

Connection lost

cause (null)

Thank You.

Shakti Gupta