File content as of revision 4:5b78021768e2:

#include "mbed.h"
#include "EthernetInterface.h"
#include "platform/mbed_thread.h"
#include <MQTTClientMbedOs.h>

// Blinking rate in milliseconds
#define BLINKING_RATE_MS 500
DigitalOut led(LED1);

int arrivedcount = 0;
TCPSocket socket;
MQTTClient client(&socket);
MQTT::Message message;


char* topic_pub = "PMK-server-topic-pub";
char* topic_sub = "PMK-client-temperature";

const char *sec2str(nsapi_security_t sec)
{
    switch (sec) {
        case NSAPI_SECURITY_NONE:
            return "None";
        case NSAPI_SECURITY_WEP:
            return "WEP";
        case NSAPI_SECURITY_WPA:
            return "WPA";
        case NSAPI_SECURITY_WPA2:
            return "WPA2";
        case NSAPI_SECURITY_WPA_WPA2:
            return "WPA/WPA2";
        case NSAPI_SECURITY_UNKNOWN:
        default:
            return "Unknown";
    }
}

void messageArrived(MQTT::MessageData& md)
{
    MQTT::Message &message = md.message;
    printf("Message arrived: qos %d, retained %d, dup %d, packetid %d\r\n", message.qos, message.retained, message.dup, message.id);
    printf("Payload %.*s\r\n", message.payloadlen, (char*)message.payload);
    ++arrivedcount;
}

int main()
{   
    printf("PMK2021 Ethernet MQTT example\r\n");
    
    const char* hostname = "broker.mqttdashboard.com";
    int port = 1883;    
    // Network interface
    EthernetInterface net;    
    // Bring up the ethernet interface    
    net.connect();

    // Show the network address
    const char *ip = net.get_ip_address();
    printf("IP address is: %s\r\n", ip ? ip : "No IP");        
    
    //client = MQTTClient::(&socket);
    socket.open(&net);
    socket.connect(hostname, port);
    
    int rc=0;
    
    MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
    data.MQTTVersion = 3;
    data.clientID.cstring = "PMK-server";
    //data.username.cstring = "testuser";
    //data.password.cstring = "testpassword";
    if ((rc = client.connect(data)) != 0)
        printf("rc from MQTT connect is %d\r\n", rc);

    if ((rc = client.subscribe(topic_sub, MQTT::QOS2, messageArrived)) != 0)
        printf("rc from MQTT subscribe is %d\r\n", rc);
 

    while (true) {
        led = !led;
        thread_sleep_for(BLINKING_RATE_MS);
        printf("Server Yielding   "); 
        client.yield(1000);
        printf(" -> Yielded\r\n"); 
        
    }
}