Beaglebone Black/Mosquitto

Install from git

1. apt-get update # Better safe than sorry
2. apt-get install libssl-dev
3. apt-get install docbook docbook-xml docbook-xsl
4. apt-get install xsltproc
5. apt-get install libsystemd-dev
6. apt install libcjson1 libcjson-dev
7. cd
8. git clone https://github.com/eclipse/mosquitto.git
9. cd mosquitto
10. vi config.mk – set WITH_SYSTEMD:=yes
11. make all
12. make install
13. adduser –system mosquitto # Bemærk det er ”-”-”system
14. ln /usr/local/lib/libmosquitto.so.1 /usr/lib/arm-linux-gnueabihf/
15. Da vi er på debian en systemd implementation øsnker vi at installere service under systemd
    1. cp /home/debian/mosquitto/service/systemd/mosquitto.service.simple /etc/systemd/system/mosquitto.service
    2. ln /usr/local/sbin/mosquitto /usr/sbin/
    3. > /etc/mosquitto/mosquitto.conf # Opret tom config fil (se eksempel fil)
    4. systemctl enable mosquitto.service
    5. service mosquitto start
    6. service mosquitto status
    7. Genstart og se den er startet automatisk
    8. Check grundlæggende installation
    9. mosquitto –v # i en terminal (Brooker)
    10. mosquitto_sub -h localhost –t "temperatur/sommerhus/stue" # i anden terminal (client/subscriber) brug evt -d for debug (Se alle feltet)
    11. mosquitto_pub -h localhost -t "temperatur/sommerhus/stue" -m "24" # i tredje terminal (client/publisher)

Example

• MQTT Broker: 188.177.229.190

//Author: heth@mercantec.dk
//Date..: 19. nov 2020
//Ver...: 0.2 beta
//
//Modification:
//   01/04/2022 - Simplified: Only one mosquitto struct used in main()
//
//INFORMATION
//Mosquitto docementation:
//   - https://mosquitto.org/documentation/
//   - https://github.com/eclipse/mosquitto (Se under exanples)
//Compile with : gcc mqtt_ex1.c -lmosquitto -o mqtt_ex1

int number;

void on_connect1(struct mosquitto *mosq, void *obj, int result)
{
    int rc = MOSQ_ERR_SUCCESS;

    if(!result){
        mosquitto_subscribe(mosq, NULL, "henrik/cputemp/fahrenheit", 0);
    }else{
        fprintf(stderr, "%s\n", mosquitto_connack_string(result));
    }
}

void on_message1(struct mosquitto *mosq, void *obj, const struct mosquitto_message *message)
{
    struct mosquitto *mosq2 = (struct mosquitto *)obj;
        char *txtpoi, *txtpoi2;
        printf("struct mosquitto_message contains:\n");
        printf("  mid (int).............: %i\n", message->mid );
        printf("  topic (* char)........: %s\n", message->topic );
        printf("  payload (* void)......: %p", message->payload );
        txtpoi = malloc(message->payloadlen + 1);
        if ( txtpoi == 0 ) {
                fprintf( stderr, "Malloc error\n");
        } else {
                strncpy(txtpoi, message->payload, message->payloadlen);
                txtpoi[message->payloadlen] = 0;
                printf("  Message: [%s]\n", txtpoi);
        }
        printf("  payloadlen (int)......: %i\n", message->payloadlen );
        printf("  qos (int).............: %i\n", message->qos );
        printf("  retain (int)..........: %i\n", message->retain );

        txtpoi2 = malloc( message->payloadlen + 20);
        sprintf(txtpoi2, "#%i:%s", number, txtpoi);
        number++;

        mosquitto_publish(mosq, NULL, "user/henrik/english", strlen(txtpoi2), txtpoi2,  message->qos, message->retain);
        free(txtpoi2);
        free(txtpoi);
}

int main(int argc, char *argv[])
{
    struct mosquitto *mosq1;
    int version[3];
    number = 1; // Init mesage number

    mosquitto_lib_init();
    mosquitto_lib_version(&version[0],&version[1],&version[2]);
    printf("Mosquitto library version. %i.%i.%i\n", version[0], version[1], version[2]);

    mosq1 = mosquitto_new(NULL, true, NULL);

    mosquitto_connect_callback_set(mosq1, on_connect1);
    mosquitto_message_callback_set(mosq1, on_message1);

    mosquitto_connect(mosq1, "188.177.229.190", 1883, 60);  // Replace localhost with IP address of broker


    mosquitto_loop_forever(mosq1, -1, 1);

    mosquitto_destroy(mosq1);

    mosquitto_lib_cleanup();

    return 0;
}