From 26f938772b29c8c42de9c6596b4b4a99c3e2cbb4 Mon Sep 17 00:00:00 2001
From: Peter M. Groen <pgroen@msimini64.osdev.nl>
Date: Mon, 14 Feb 2022 14:02:06 +0100
Subject: [PATCH] Added examples.

---
 README.md | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 112 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index e240307..39c934b 100644
--- a/README.md
+++ b/README.md
@@ -41,4 +41,115 @@ later the "pub" part. If all went well, you should see two screens in sync runni
    Open terminal 2
    $ bin/test_mqtt_pub
    ```
-Screen 2 is sending, Screen 1 is receiving.
\ No newline at end of file
+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;
+}
+```
+
+Now it will be very easy to send and receive messages from a broker without the hassle of administration.
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