trusty (3) libmosquitto.3.gz

NAME

       libmosquitto - MQTT version 3.1 client library

DESCRIPTION

       This  is  an  overview  of  how  to  use  libmosquitto to create MQTT aware client programs. There may be
       separate man pages on each of the functions described here in the future. There  are  also  bindings  for
       libmosquitto for C++ and Python. They are not documented here.

       This is fairly incomplete, please see mosquitto.h for a better description of the functions.

STATUS

       The  libmosquitto  api  is  currently  regarded  as  experimental  and  unstable and may change in future
       releases.

LIBMOSQUITTO SYMBOL NAMES

       All public functions in libmosquitto have the prefix "mosquitto_". Any other  functions  defined  in  the
       source  code  are to be treated as private functions and may change between any release. Do not use these
       functions!

FUNCTIONS

   LIBRARY VERSION
       unsigned long mosquitto_lib_version (int *major, int *minor, int *revision);

       Obtain version information about the library. If any of major, minor or revision are not NULL  they  will
       return  the  corresponding version numbers. The return value is an integer representation of the complete
       version number (e.g. 9000 for 0.9) that can be used for comparisons.

   LIBRARY INITIALISATION AND CLEANUP
       int mosquitto_lib_init (void);
       int mosquitto_lib_cleanup (void);

   CLIENT CONSTRUCTOR/DESTRUCTOR
       struct mosquitto *mosquitto_new (const char *id, void *obj);
       void mosquitto_destroy (struct mosquitto *mosq);

   LOGGING
       int mosquitto_log_init (struct mosquitto *mosq, int priorities, int destinations);

       Configure the logging settings for this client. Returns 0 on success, 1 on error.

       Set priorities by ORing any of the items in the following list:

       • MOSQ_LOG_INFO

       • MOSQ_LOG_NOTICE

       • MOSQ_LOG_WARNING

       • MOSQ_LOG_ERROR

       • MOSQ_LOG_DEBUG

       Set destinations by ORing any of the items in the following list:

       • MOSQ_LOG_NONE

       • MOSQ_LOG_STDOUT

       • MOSQ_LOG_STDERR

   WILLS
       int mosquitto_will_set (struct mosquitto *mosq, bool will, const char *topic, uint32_t payloadlen, const
                              uint8_t *payload, int qos, bool retain);

   CONNECT/DISCONNECT
       void mosquitto_connect (struct mosquitto *mosq, const char *host, int port, int keepalive, bool
                              clean_session);
       void mosquitto_reconnect (struct mosquitto *mosq);
       int mosquitto_disconnect (struct mosquitto *mosq);

   PUBLISH
       int mosquitto_publish (struct mosquitto *mosq, uint16_t *mid, const char *topic, uint32_t payloadlen,
                             const uint8_t *payload, int qos, bool retain);

   SUBSCRIBE/UNSUBSCRIBE
       int mosquitto_subscribe (struct mosquitto *mosq, uint16_t *mid, const char *sub, int qos);
       int mosquitto_unsubscribe (struct mosquitto *mosq, uint16_t *mid, const char *sub);

   NETWORK LOOP
       int mosquitto_loop (struct mosquitto *mosq, int timeout);
       int mosquitto_loop_read (struct mosquitto *mosq);
       int mosquitto_loop_write (struct mosquitto *mosq);
       int mosquitto_loop_misc (struct mosquitto *mosq);
       int mosquitto_socket (struct mosquitto *mosq);

   CALLBACKS
       See mosquitto.h

EXAMPLES

       #include <mosquitto.h>

       void my_message_callback(void *obj, struct mosquitto_message *message)
       {
            if(message->payloadlen){
                 printf("%s %s\n", message->topic, message->payload);
            }else{
                 printf("%s (null)\n", message->topic);
            }
            fflush(stdout);
       }

       void my_connect_callback(void *obj, int result)
       {
            struct mosquitto *mosq = obj;

            int i;
            if(!result){
                 mosquitto_subscribe(mosq, topics[i], topic_qos);
            }else{
                 fprintf(stderr, "Connect failed\n");
            }
       }

       void my_subscribe_callback(void *obj, uint16_t mid, int qos_count, const uint8_t *granted_qos)
       {
            int i;

            printf("Subscribed (mid: %d): %d", mid, granted_qos[0]);
            for(i=1; i<qos_count; i++){
                 printf(", %d", granted_qos[i]);
            }
            printf("\n");
       }

       int main(int argc, char *argv[])
       {
            char id[30];
            int i;
            char *host = "localhost";
            int port = 1883;
            int keepalive = 60;
            bool clean_session = true;
            struct mosquitto *mosq = NULL;

            mosq = mosquitto_new(id, NULL);
            if(!mosq){
                 fprintf(stderr, "Error: Out of memory.\n");
                 return 1;
            }
            mosquitto_log_init(mosq, MOSQ_LOG_DEBUG | MOSQ_LOG_ERR | MOSQ_LOG_WARNING
                      | MOSQ_LOG_NOTICE | MOSQ_LOG_INFO, MOSQ_LOG_STDERR);

            mosquitto_connect_callback_set(mosq, my_connect_callback);
            mosquitto_message_callback_set(mosq, my_message_callback);
            mosquitto_subscribe_callback_set(mosq, my_subscribe_callback);

            if(mosquitto_connect(mosq, host, port, keepalive, clean_session)){
                 fprintf(stderr, "Unable to connect.\n");
                 return 1;
            }

            while(!mosquitto_loop(mosq, -1)){
            }
            mosquitto_destroy(mosq);
            return 0;
       }

SEE ALSO

       mosquitto(8) mqtt(7)

AUTHOR

       Roger Light <roger@atchoo.org>

                                                 5 February 2012                                 libmosquitto(3)