MQTT Client API
MQTT Client API provides sequential API built on top of MQTT Client.
1/*
2 * MQTT client API example with ESP device to test server.
3 * It utilizes sequential mode without callbacks in one user thread
4 *
5 * Once device is connected to network,
6 * it will try to connect to mosquitto test server and start the MQTT.
7 *
8 * If successfully connected, it will publish data to "lwesp_mqtt_topic" topic every x seconds.
9 *
10 * To check if data are sent, you can use mqtt-spy PC software to inspect
11 * test.mosquitto.org server and subscribe to publishing topic
12 */
13
14#include "mqtt_client_api.h"
15#include "lwesp/apps/lwesp_mqtt_client_api.h"
16#include "lwesp/lwesp_mem.h"
17
18/**
19 * \brief Connection information for MQTT CONNECT packet
20 */
21static const lwesp_mqtt_client_info_t mqtt_client_info = {
22 .keep_alive = 10,
23
24 /* Server login data */
25 .user = "8a215f70-a644-11e8-ac49-e932ed599553",
26 .pass = "26aa943f702e5e780f015cd048a91e8fb54cca28",
27
28 /* Device identifier address */
29 .id = "869f5a20-af9c-11e9-b01f-db5cf74e7fb7",
30};
31
32static char mqtt_topic_str[256]; /*!< Topic string */
33static char mqtt_topic_data[256]; /*!< Data string */
34
35/**
36 * \brief Generate random number and write it to string
37 * It utilizes simple pseudo random generator, super simple one
38 * \param[out] str: Output string with new number
39 */
40static void
41prv_generate_random(char* str) {
42 static uint32_t random_beg = 0x8916;
43 random_beg = random_beg * 0x00123455 + 0x85654321;
44 sprintf(str, "%u", (unsigned)((random_beg >> 8) & 0xFFFF));
45}
46
47/**
48 * \brief MQTT client API thread
49 * \param[in] arg: User argument
50 */
51void
52lwesp_mqtt_client_api_thread(void const* arg) {
53 lwesp_mqtt_client_api_p client;
54 lwesp_mqtt_conn_status_t conn_status;
55 lwesp_mqtt_client_api_buf_p buf;
56 lwespr_t res;
57 char random_str[10];
58
59 LWESP_UNUSED(arg);
60
61 /* Create new MQTT API */
62 if ((client = lwesp_mqtt_client_api_new(256, 128)) == NULL) {
63 goto terminate;
64 }
65
66 while (1) {
67 /* Make a connection */
68 printf("Joining MQTT server\r\n");
69
70 /* Try to join */
71 conn_status = lwesp_mqtt_client_api_connect(client, "mqtt.mydevices.com", 1883, &mqtt_client_info);
72 if (conn_status == LWESP_MQTT_CONN_STATUS_ACCEPTED) {
73 printf("Connected and accepted!\r\n");
74 printf("Client is ready to subscribe and publish to new messages\r\n");
75 } else {
76 printf("Connect API response: %d\r\n", (int)conn_status);
77 lwesp_delay(5000);
78 continue;
79 }
80
81 /* Subscribe to topics */
82 sprintf(mqtt_topic_str, "v1/%s/things/%s/cmd/#", mqtt_client_info.user, mqtt_client_info.id);
83 if (lwesp_mqtt_client_api_subscribe(client, mqtt_topic_str, LWESP_MQTT_QOS_AT_LEAST_ONCE) == lwespOK) {
84 printf("Subscribed to topic\r\n");
85 } else {
86 printf("Problem subscribing to topic!\r\n");
87 }
88
89 while (1) {
90 /* Receive MQTT packet with 1000ms timeout */
91 if ((res = lwesp_mqtt_client_api_receive(client, &buf, 5000)) == lwespOK) {
92 if (buf != NULL) {
93 printf("Publish received!\r\n");
94 printf("Topic: %s, payload: %s\r\n", buf->topic, buf->payload);
95 lwesp_mqtt_client_api_buf_free(buf);
96 buf = NULL;
97 }
98 } else if (res == lwespCLOSED) {
99 printf("MQTT connection closed!\r\n");
100 break;
101 } else if (res == lwespTIMEOUT) {
102 printf("Timeout on MQTT receive function. Manually publishing.\r\n");
103
104 /* Publish data on channel 1 */
105 prv_generate_random(random_str);
106 sprintf(mqtt_topic_str, "v1/%s/things/%s/data/1", mqtt_client_info.user, mqtt_client_info.id);
107 sprintf(mqtt_topic_data, "temp,c=%s", random_str);
108 lwesp_mqtt_client_api_publish(client, mqtt_topic_str, mqtt_topic_data, strlen(mqtt_topic_data),
109 LWESP_MQTT_QOS_AT_LEAST_ONCE, 0);
110 }
111 }
112 //goto terminate;
113 }
114
115terminate:
116 lwesp_mqtt_client_api_delete(client);
117 printf("MQTT client thread terminate\r\n");
118 lwesp_sys_thread_terminate(NULL);
119}
- group LWESP_APP_MQTT_CLIENT_API
Sequential, single thread MQTT client API.
Typedefs
-
typedef struct lwesp_mqtt_client_api_buf *lwesp_mqtt_client_api_buf_p
Pointer to lwesp_mqtt_client_api_buf_t structure.
Functions
-
lwesp_mqtt_client_api_p lwesp_mqtt_client_api_new(size_t tx_buff_len, size_t rx_buff_len)
Create new MQTT client API.
- Parameters
tx_buff_len – [in] Maximal TX buffer for maximal packet length
rx_buff_len – [in] Maximal RX buffer
- Returns
Client handle on success,
NULL
otherwise
-
void lwesp_mqtt_client_api_delete(lwesp_mqtt_client_api_p client)
Delete client from memory.
- Parameters
client – [in] MQTT API client handle
-
lwesp_mqtt_conn_status_t lwesp_mqtt_client_api_connect(lwesp_mqtt_client_api_p client, const char *host, lwesp_port_t port, const lwesp_mqtt_client_info_t *info)
Connect to MQTT broker.
- Parameters
client – [in] MQTT API client handle
host – [in] TCP host
port – [in] TCP port
info – [in] MQTT client info
- Returns
LWESP_MQTT_CONN_STATUS_ACCEPTED on success, member of lwesp_mqtt_conn_status_t otherwise
-
lwespr_t lwesp_mqtt_client_api_subscribe(lwesp_mqtt_client_api_p client, const char *topic, lwesp_mqtt_qos_t qos)
Subscribe to topic.
- Parameters
client – [in] MQTT API client handle
topic – [in] Topic to subscribe on
qos – [in] Quality of service. This parameter can be a value of lwesp_mqtt_qos_t
- Returns
-
lwespr_t lwesp_mqtt_client_api_unsubscribe(lwesp_mqtt_client_api_p client, const char *topic)
Unsubscribe from topic.
-
lwespr_t lwesp_mqtt_client_api_publish(lwesp_mqtt_client_api_p client, const char *topic, const void *data, size_t btw, lwesp_mqtt_qos_t qos, uint8_t retain)
Publish new packet to MQTT network.
- Parameters
client – [in] MQTT API client handle
topic – [in] Topic to publish on
data – [in] Data to send
btw – [in] Number of bytes to send for data parameter
qos – [in] Quality of service. This parameter can be a value of lwesp_mqtt_qos_t
retain – [in] Set to
1
for retain flag,0
otherwise
- Returns
-
uint8_t lwesp_mqtt_client_api_is_connected(lwesp_mqtt_client_api_p client)
Check if client MQTT connection is active.
- Parameters
client – [in] MQTT API client handle
- Returns
1
on success,0
otherwise
-
lwespr_t lwesp_mqtt_client_api_receive(lwesp_mqtt_client_api_p client, lwesp_mqtt_client_api_buf_p *p, uint32_t timeout)
Receive next packet in specific timeout time.
Note
This function can be called from separate thread than the rest of API function, which allows you to handle receive data separated with custom timeout
- Parameters
client – [in] MQTT API client handle
p – [in] Pointer to output buffer
timeout – [in] Maximal time to wait before function returns timeout
- Returns
lwespOK on success, lwespCLOSED if MQTT is closed, lwespTIMEOUT on timeout
-
void lwesp_mqtt_client_api_buf_free(lwesp_mqtt_client_api_buf_p p)
Free buffer memory after usage.
- Parameters
p – [in] Buffer to free
-
struct lwesp_mqtt_client_api_buf_t
- #include <lwesp_mqtt_client_api.h>
MQTT API RX buffer.
-
typedef struct lwesp_mqtt_client_api_buf *lwesp_mqtt_client_api_buf_p