File content as of revision 1:49fb5754df16:

// In this example an MQTT client is created using an ENC28J60
// It is publishing a simple 'example/hello' message 'Hello World.'
// and subscribes to 'outdoor/temperature' messages
// UIPEthernet library is used to drive the ENC28J60
#include "mbed.h"
#include <UIPEthernet.h>
#include <UIPClient.h>
#include <MQTTClient.h>
#include <string>

using namespace std;

// UIPEthernet is the name of a global instance of UIPEthernetClass.
// Do not change the name! It is used within the UIPEthernet library.
// Adapt the SPI pin names to your mbed platform/board if not present yet.
#if defined(TARGET_LPC1768)
UIPEthernetClass UIPEthernet(p11, p12, p13, p8); // mosi, miso, sck, cs
#elif defined(TARGET_LPC1114)
UIPEthernetClass UIPEthernet(dp2, dp1, dp6, dp25); // mosi, miso, sck, cs
#elif defined(TARGET_LPC11U68)
UIPEthernetClass UIPEthernet(P0_9, P0_8, P1_29, P0_2); // mosi, miso, sck, cs
#elif defined (TARGET_NUCLEO_F103RB)
UIPEthernetClass UIPEthernet(PB_5, PB_4, PB_3, PB_6); // mosi, miso, sck, cs
#endif

//Serial pc(PA_9, PA_10);
Serial pc(USBTX, USBRX);


// Make sure that the MAC number is unique within the connected network.
const uint8_t    MY_MAC[6] = {0x00,0x01,0x02,0x03,0x04,0x05};
// IP address must be unique and compatible with your network too. Change as appropriate.
const IPAddress  MY_IP(192,168,1,181);
char             message_buff[100];
IPAddress        serverIP(192,168,1,30);     // MQTT server (e.g. 'mosquitto' running on a Ubuntu PC or Raspberry Pi)
EthernetClient   ethernetClient;
void             onMqttMessage(char* topic, uint8_t* payload, unsigned int length);
MQTTClient       mqttClient(serverIP, 1883, onMqttMessage, ethernetClient);

int main()
{
    const int   MAX_COUNT = 5;
    int         i = 0;
    bool        connected = false;
    char*       payload = "Hello World.";
    time_t      t = 0;
    time_t      lastTime = t;

    // initialize the ethernet device
    UIPEthernet.begin(MY_MAC, MY_IP);
//    IPAddress localIP = UIPEthernet.localIP();
//    pc.printf("IP = ");
//    for(uint8_t i = 0; i < 3; i++)
//        pc.printf("%d.", localIP[i]);
//    pc.printf("%d\r\n", localIP[3]);
    pc.printf("Connecting to MQTT server ..\r\n");
    do {
        wait(1.0);
        connected = mqttClient.connect("myMQTTHelloClient");
    } while(!connected && (i < MAX_COUNT));

    if(connected) {
        pc.printf("MQTT Server connected.\r\n");
        mqttClient.subscribe("outdoor/temperature");
        pc.printf("Subscribed to: outdoor/temperature\r\n");
    } else {
        pc.printf("Failed to connect to MQTT server.\r\n");
    }

    while(1) {
        t = time(NULL);
        if(t > (lastTime + 5)) {
            lastTime = t;
            if(connected) {
                mqttClient.publish("example/hello", payload);
                pc.printf("Published: example/hello\r\n");
            }

        }
        mqttClient.loop();  // MQTT client loop processing
    }
}

void onMqttMessage(char* topic, uint8_t* payload, unsigned int length)
{
    int i = 0;

    pc.printf("Message arrived:\r\n");
    pc.printf("  Topic: %s\r\n", topic);
    pc.printf("  Length: %d\r\n", length);

    // create character buffer with ending null terminator (string)
    for(i = 0; i < length; i++) {
        message_buff[i] = payload[i];
    }

    message_buff[i] = '\0';
    pc.printf("  Payload: %s\r\n", message_buff);
}