How to set the configuration properties for Mosquitto in c++? - c++

Question

I am writing mosquitto code for consuming the message after subscribing to a particular topic. Now I want to set different configuration for mosquitto like
autosave_interval 100
persistence true
persistence_location /var/lib/mosquitto/
persistence_file mosquitto.db
But I have no idea how to set this configuration in c++. I tried to google it but could not found any result. Plz, help. Below is c++ code for mosquito
myMosq.h
/*
* myMosq.h
*
* Created on: Jul 28, 2016
* Author: nilav
*/
#include <iostream>
#ifndef MYMOSQ_H_
#define MYMOSQ_H_
#include <mosquittopp.h>
#include <mosquitto.h>
using namespace std;
class myMosq : public mosqpp::mosquittopp
{
private:
const char * host;
const char * id;
const char * topic;
int port;
int keepalive;
void on_connect(int rc);
void on_message(const struct mosquitto_message *message);
void on_disconnect(int rc);
void on_subscribe(int mid, int qos_count, const int *granted_qos);
void on_publish(int mid);
void on_unsubscribe(int mid);
public:
myMosq(const char *id, const char * _topic, const char *host, int port);
~myMosq();
bool send_message(string responseMessage);
bool receive_message();
void writeToDatabase(string query);
};
#endif
myMosq.cpp
#include <cstdio>
#include <cstring>
#include <iostream>
#include "myMosq.h"
#include <mosquittopp.h>
#include "Configuration.h"
#include "Databases.h"
using namespace std;
Configuration configuration;
myMosq::myMosq(const char * _id,const char * _topic, const char * _host, int _port) : mosquittopp(_id)
{
mosqpp::lib_init(); // Mandatory initialization for mosquitto library
this->keepalive = 60; // Basic configuration setup for myMosq class
this->id = _id;
this->port = _port;
this->host = _host;
this->topic = _topic;
connect_async(host, // non blocking connection to broker request
port,
keepalive);
loop_start(); // Start thread managing connection / publish / subscribe
};
myMosq::~myMosq() {
loop_stop(); // Kill the thread
mosqpp::lib_cleanup(); // Mosquitto library cleanup
}
bool myMosq::receive_message()
{
int set = subscribe(NULL, configuration.subscriptionTopic.c_str(),2);
return set;
}
bool myMosq::send_message(string responseMessage) {
int ret = publish(NULL,configuration.producerTopic.c_str(),strlen(responseMessage.c_str()),responseMessage.c_str(),1,false);
return (ret = MOSQ_ERR_SUCCESS);
}
void myMosq::on_disconnect(int rc) {
std::cout << ">> myMosq - disconnection(" << rc << ")" << std::endl;
}
void myMosq::on_connect(int rc)
{
if ( rc == 0 ) {
std::cout << ">> myMosq - connected with server" << std::endl;
} else {
std::cout << ">> myMosq - Impossible to connect with server(" << rc << ")" << std::endl;
}
}
void myMosq::on_message(const struct mosquitto_message *message) {
char * pchar = (char*)(message->payload);
string str(pchar);
writeToDatabase(str);
}
void myMosq::on_subscribe(int mid, int qos_count, const int *granted_qos)
{
std::cout << ">> subscription succeeded (" << mid << ") " << std::endl;
}
void myMosq::on_publish(int mid) {
std::cout << ">> myMosq - Message (" << mid << ") succeed to be published " << std::endl;
}
void myMosq::writeToDatabase(string query) {
Databases* database = new Databases(configuration.db,
configuration.dbPort, configuration.username, configuration.password,
configuration.schema);
database->writeDatabase(query);
if(database->responseMessage == "") {
database->responseMessage = "SUCCESS";
}
this->send_message(database->responseMessage);
}
void myMosq::on_unsubscribe(int mid) {
cout<<"unscubscribed";
};

Answer 1

The options you are seeing are for mosquitto broker which acts almost like a server.
Mosquitto C++ library is a client library and those options(e.g. autosave_interval) are not valid for a client. Regarding persistance, mosquitto C/C++ client library doesn't offer file persistance currently.