How to declare the Paho MQTT C++ in another c++ file? - c++

Question

Below is my project structure,
root#user-VirtualBox:/home/user/octane_etk_sample-6.0.0.240# ls
bin include paho.mqtt.c speedway_embedded_example.cpp
cap lib paho.mqtt.cpp VERSION
cap_description.in Makefile SCMREV
I have the paho.mqtt.cpp package inside the project directory i.e.,octane_etk_sample-6.0.0.240 and I have installed all the steps which is mentioned in https://github.com/eclipse/paho.mqtt.cpp.
Now, I have included the MQTTAsync header file in speedway_embedded_example.cpp as like below,
#include <iostream>
#include <string>
#include <algorithm>
#include <signal.h>
#include <stdio.h>
#include <cstdlib>
#include "ltkcpp.h"
#include "impinj_ltkcpp.h"
#include "time.h"
#include "/home/user/octane_etk_sample-6.0.0.240/paho.mqtt.c/src/MQTTAsync.h"
After including the header file, I am trying to establish the MQTT client connection inside the public class,
void
CMyApplication::printOneTagReportData (
CTagReportData * pTagReportData)
{
string address = "tcp://mqtt1.mindlogic.com:1883";
cout << "OK\n" << address;
mqtt::async_client cli(address, "", 120, "data-persist");
}
When I try to make a speedway_embedded_example file, I am getting below error,
root#user-VirtualBox:/home/mindlogic/octane_etk_sample-6.0.0.240# make
mkdir -p ./bin
g++ \
-m32 -Wno-write-strings \
-Iinclude \
speedway_embedded_example.cpp \
-Llib -lltkcpp_x86 -lltkcppimpinj_x86 -lxml2_x86 \
-L/usr/bin -ldl -lssl -lcrypto \
-o bin/speedwayr_x86
speedway_embedded_example.cpp: In member function ‘void CMyApplication::printOneTagReportData(LLRP::CTagReportData*)’:
speedway_embedded_example.cpp:1650:4: error: ‘mqtt’ has not been declared
mqtt::async_client cli(address, "", 120, "data-persist");
Will anyone help me out to establish a client connection in the above scenario?

Answer 1

You're including the C library, which doesn't have namespaces.
You (likely) want the C++ library.
https://github.com/eclipse/paho.mqtt.cpp
Or better yet, since you included the embedded tag, you may want to use
https://github.com/eclipse/paho.mqtt.embedded-c
which has embedded code for both C and C++. You should use the example code provided by the library you're using.