File content as of revision 3:5e31b4687aad:

/*
  MQTTClient.h - A simple client for MQTT.
  Nicholas O'Leary
  http://knolleary.net

  Ported to mbed by Zoltan Hudak <hudakz@outlook.com>
*/
#ifndef MQTTClient_h
#define MQTTClient_h

#include "mbed.h"
#include "TcpClient.h"

#define MQTT_MAX_PACKET_SIZE   256  // MQTT_MAX_PACKET_SIZE : Maximum packet size
#define MQTT_KEEPALIVE          15  // MQTT_KEEPALIVE : keepAlive interval in Seconds
#define MQTTPROTOCOLVERSION      3
#define MQTTCONNECT         1 << 4  // Client request to connect to Server
#define MQTTCONNACK         2 << 4  // Connect Acknowledgment
#define MQTTPUBLISH         3 << 4  // Publish message
#define MQTTPUBACK          4 << 4  // Publish Acknowledgment
#define MQTTPUBREC          5 << 4  // Publish Received (assured delivery part 1)
#define MQTTPUBREL          6 << 4  // Publish Release (assured delivery part 2)
#define MQTTPUBCOMP         7 << 4  // Publish Complete (assured delivery part 3)
#define MQTTSUBSCRIBE       8 << 4  // Client Subscribe request
#define MQTTSUBACK          9 << 4  // Subscribe Acknowledgment
#define MQTTUNSUBSCRIBE     10<< 4  // Client Unsubscribe request
#define MQTTUNSUBACK        11<< 4  // Unsubscribe Acknowledgment
#define MQTTPINGREQ         12<< 4  // PING Request
#define MQTTPINGRESP        13<< 4  // PING Response
#define MQTTDISCONNECT      14<< 4  // Client is Disconnecting
#define MQTTReserved        15<< 4  // Reserved
#define MQTTQOS0            (0<< 1)
#define MQTTQOS1            (1<< 1)
#define MQTTQOS2            (2<< 1)

class   MQTTClient
{
    TcpClient*      _client;
    uint8_t         _buffer[MQTT_MAX_PACKET_SIZE];
    uint16_t        _nextMsgId;
    unsigned long   _lastOutActivity;
    unsigned long   _lastInActivity;
    bool            _pingOutstanding;
    IpAddress       _ip;
    char*           _domain;
    uint16_t        _port;
    Stream*         _stream;

    void            (*_onMessage) (char*, uint8_t*, unsigned int);
    uint16_t        _readPacket(uint8_t* );
    uint8_t         _readByte(void);
    bool            _write(uint8_t header, uint8_t* buf, uint16_t length);
    uint16_t        _writeString(const char* string, uint8_t* buf, uint16_t pos);
public:
    MQTTClient(void);
    MQTTClient(IpAddress& , uint16_t, void (* ) (char*, uint8_t*, unsigned int), TcpClient& client);
    MQTTClient(IpAddress& , uint16_t, void (* ) (char*, uint8_t*, unsigned int), TcpClient& client, Stream& );
    MQTTClient(const char* , uint16_t, void (* ) (char*, uint8_t*, unsigned int), TcpClient& client);
    MQTTClient(const char* , uint16_t, void (* ) (char*, uint8_t*, unsigned int), TcpClient& client, Stream& );
    bool    connect(const char* );
    bool    connect(const char* , const char* , const char* );
    bool    connect(const char* , const char* , uint8_t, uint8_t, const char* );
    bool    connect(const char* , const char* , const char* , const char* , uint8_t, uint8_t, const char* );
    void    disconnect(void);
    bool    publish(const char* , const char* );
    bool    publish(const char* , uint8_t* , unsigned int);
    bool    publish(const char* , uint8_t* , unsigned int, bool);
    bool    subscribe(const char* );
    bool    subscribe(const char* , uint8_t qos);
    bool    unsubscribe(const char* );
    bool    loop(void);
    bool    connected(void);
};
#endif