1# ESP-MQTT MQTT over WSS Sample application
2(See the README.md file in the upper level 'examples' directory for more information about examples.)
3
4This example connects to the broker mqtt.eclipseprojects.io over secure websockets and as a demonstration subscribes/unsubscribes and send a message on certain topic.
5(Please note that the public broker is maintained by the community so may not be always available, for details please see this [disclaimer](https://iot.eclipse.org/getting-started/#sandboxes))
6
7It uses ESP-MQTT library which implements mqtt client to connect to mqtt broker.
8
9## How to use example
10
11### Hardware Required
12
13This example can be executed on any ESP32 board, the only required interface is WiFi and connection to internet.
14
15### Configure the project
16
17* Open the project configuration menu (`idf.py menuconfig`)
18* Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in [examples/protocols/README.md](../../README.md) for more details.
19* When using Make build system, set `Default serial port` under `Serial flasher config`.
20
21Note how to create a PEM certificate for mqtt.eclipseprojects.io:
22
23PEM certificate for this example could be extracted from an openssl `s_client` command connecting to mqtt.eclipseprojects.io.
24In case a host operating system has `openssl` and `sed` packages installed, one could execute the following command to download and save the root certificate to a file (Note for Windows users: Both Linux like environment or Windows native packages may be used).
25```
26echo "" | openssl s_client -showcerts -connect mqtt.eclipseprojects.io:443 | sed -n "1,/Root/d; /BEGIN/,/END/p" | openssl x509 -outform PEM >mqtt_eclipse_org.pem
27```
28Please note that this is not a general command for downloading a root certificate for an arbitrary host;
29this command works with mqtt.eclipseprojects.io as the site provides root certificate in the chain, which then could be extracted
30with text operation.
31
32### Build and Flash
33
34Build the project and flash it to the board, then run monitor tool to view serial output:
35
36```
37idf.py -p PORT flash monitor
38```
39
40(To exit the serial monitor, type ``Ctrl-]``.)
41
42See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
43
44## Example Output
45
46```
47I (3714) event: sta ip: 192.168.0.139, mask: 255.255.255.0, gw: 192.168.0.2
48I (3714) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
49I (3964) MQTT_CLIENT: Sending MQTT CONNECT message, type: 1, id: 0000
50I (4164) MQTTWSS_EXAMPLE: MQTT_EVENT_CONNECTED
51I (4174) MQTTWSS_EXAMPLE: sent publish successful, msg_id=41464
52I (4174) MQTTWSS_EXAMPLE: sent subscribe successful, msg_id=17886
53I (4174) MQTTWSS_EXAMPLE: sent subscribe successful, msg_id=42970
54I (4184) MQTTWSS_EXAMPLE: sent unsubscribe successful, msg_id=50241
55I (4314) MQTTWSS_EXAMPLE: MQTT_EVENT_PUBLISHED, msg_id=41464
56I (4484) MQTTWSS_EXAMPLE: MQTT_EVENT_SUBSCRIBED, msg_id=17886
57I (4484) MQTTWSS_EXAMPLE: sent publish successful, msg_id=0
58I (4684) MQTTWSS_EXAMPLE: MQTT_EVENT_SUBSCRIBED, msg_id=42970
59I (4684) MQTTWSS_EXAMPLE: sent publish successful, msg_id=0
60I (4884) MQTT_CLIENT: deliver_publish, message_length_read=19, message_length=19
61I (4884) MQTTWSS_EXAMPLE: MQTT_EVENT_DATA
62TOPIC=/topic/qos0
63DATA=data
64I (5194) MQTT_CLIENT: deliver_publish, message_length_read=19, message_length=19
65I (5194) MQTTWSS_EXAMPLE: MQTT_EVENT_DATA
66TOPIC=/topic/qos0
67DATA=data
68```
69
70
71
72