e0b1fe64
 Peter M. Groen
Fixed script.
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Just check your package manager for the correct package-name.
# Tutorial
* Clone this repository :
```
git clone http://gitlab.osdev.nl/open_source/mqtt-cpp.git
```
* Change to the repo and run the submodules script :
```
$ cd mqtt-cpp
$ scripts/setup_submodules -i
```
This will add the cmake directory and versioning.
* Create a build directory and start the build.
```
$ mkdir build
$ cd build
$ cmake ../
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e0b1fe64
Peter M. Groen
Fixed script.
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```
And you're all set. In build/bin there are two examples, test_mqtt_pu and test_mqtt_sub. Have a broker running,
like mosquitto or flashmq capable of accepting anonymous connections. Start the "sub" part and couple of moments
later the "pub" part. If all went well, you should see two screens in sync running.
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26f93877
Peter M. Groen
Added examples.
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Screen 2 is sending, Screen 1 is receiving.
# Using the library.
Using mqtt-cpp is pretty straight forward. No real magic is happening. Beware of the fact that the library uses the namespace :
```
osdev::components::mqtt
```
## Publishing..
To create a publisher, a simple member needs to be created.
Header :
```
#pragma once
// std
#include <memory>
#include <string>
// osdev::components::mqtt
#include "mqttclient.h"
#include "compat-c++14.h"
class Publisher
{
public:
Publisher(const std::string &client_id);
virtual ~Publisher() {}
void connect( const std::string &hostname, int portnumber = 1883, const std::string &username = std::string(), const std::string &password = std::string() );
void publish( const std::string &message_topic, const std::string &message_payload );
private:
osdev::components::mqtt::MqttClient m_mqtt_client;
};
```
Implementation
```
// osdev::components::mqtt
// #include "token.h"
// mqtt_tests
#include "publisher.h"
Publisher::Publisher(const std::string &client_id)
: m_mqtt_client( client_id )
{
}
void Publisher::connect( const std::string &hostname, int portnumber, const std::string &username, const std::string &password )
{
m_mqtt_client.connect( hostname, portnumber, osdev::components::mqtt::Credentials( username, password ) );
std::cout << "Client state : " << m_mqtt_client.state() << std::endl;
}
void Publisher::publish( const std::string &message_topic, const std::string &message_payload )
{
osdev::components::mqtt::MqttMessage message( message_topic, true, false, message_payload );
std::cout << "[Publisher::publish] - Publising message : " << message_payload << " to topic : " << message_topic << std::endl;
osdev::components::mqtt::Token t_result = m_mqtt_client.publish( message, 0 );
}
```
## Subscribing
TO create a subscriber, a bit more work is involved. A subscription is dependant on a callback in which the data is handled to your liking. It is necessary to inherit from MqttSubscriberBase and override the "receive_data" method.
subscriber.h
```
#pragma once
// std
#include <string>
// mqtt-cpp
#include "mqttsubscriberbase.h"
class Subscriber : public MqttSubscriberBase
{
public:
Subscriber( const std::string &client_id );
virtual ~Subscriber() {}
protected:
void receive_data( const std::string &message_topic, const std::string &message_payload );
};
```
In the receive_data, the logic will be implemented to handle, decode and store the payload.
```
#include "subscriber.h"
#include <iostream>
Subscriber::Subscriber( const std::string &client_id )
: MqttSubscriberBase( client_id )
{
}
void Subscriber::receive_data( const std::string &message_topic, const std::string &message_payload )
{
std::cout << "[Subscriber::receive_data] - Received message : " << message_payload << " from topic : " << message_topic << std::endl;
}
```
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