Last Will and Testament using PubSubClient.h and AWS IoT, ESP8266

Other Hardware Home Automation
1

I am using PubSubClient.h to connect with AWS IoT and it worked fine with shadow topics with the following line

while (!virtual_thing.connect(virtual_thing_name.c_str())){
}

when I tried to do the same for Last Will and Testament topic with the following line , it failed with -4 MQTT state

while (!virtual_thing.connect(virtual_thing_name.c_str(), NULL, NULL, "theEndTopic", 1, true, "offline")){
}

exactly, where is the issue lying ??

2

error 4 in MQTT usually relates to "Connection Refused: Bad username or password" but are you getting this from the PubSubClient library or from the server?

3

WiFiClientSecure espClient;
PubSubClient virtual_thing(espClient);

this works

espClient.setTrustAnchors(&cert);
  espClient.setClientRSACert(&client_crt, &key);
  virtual_thing.setServer(MQTT_HOST, MQTT_PORT);
  virtual_thing.setCallback(parse);
  virtual_thing.setBufferSize(2048);
  virtual_thing.setKeepAlive(120);

  //const char* mqttUsername = NULL;
  //const char* mqttPassword = NULL;

  const char* willTopic = "/last/will/topic";
  uint8_t willQoS = 1;
  bool willRetain = true;
  const char* willMessage = "Offline";
  bool cleanSession = true;

  while (!virtual_thing.connect(virtual_thing_name.c_str())){
  //while (!virtual_thing.connect(virtual_thing_name.c_str(),NULL,NULL,willTopic,willQoS,willRetain,willMessage,cleanSession)) {       
    Serial.print(virtual_thing.state());    
    Serial.print(".");
    delay(1000);
  }

this too works

  espClient.setTrustAnchors(&cert);
  espClient.setClientRSACert(&client_crt, &key);
  virtual_thing.setServer(MQTT_HOST, MQTT_PORT);
  virtual_thing.setCallback(parse);
  virtual_thing.setBufferSize(2048);
  virtual_thing.setKeepAlive(120);

  //const char* mqttUsername = NULL;
  //const char* mqttPassword = NULL;

  const char* willTopic = "/last/will/topic";
  uint8_t willQoS = 1;
  bool willRetain = true;
  const char* willMessage = "Offline";
  bool cleanSession = true;

  //while (!virtual_thing.connect(virtual_thing_name.c_str())){
  while (!virtual_thing.connect(virtual_thing_name.c_str(),NULL,NULL/*,willTopic,willQoS,willRetain,willMessage,cleanSession*/)) {       
    Serial.print(virtual_thing.state());    
    Serial.print(".");
    delay(1000);
  }

but this is not working

  espClient.setTrustAnchors(&cert);
  espClient.setClientRSACert(&client_crt, &key);
  virtual_thing.setServer(MQTT_HOST, MQTT_PORT);
  virtual_thing.setCallback(parse);
  virtual_thing.setBufferSize(2048);
  virtual_thing.setKeepAlive(120);

  //const char* mqttUsername = NULL;
  //const char* mqttPassword = NULL;

  const char* willTopic = "/last/will/topic";
  uint8_t willQoS = 1;
  bool willRetain = true;
  const char* willMessage = "Offline";
  bool cleanSession = true;

  //while (!virtual_thing.connect(virtual_thing_name.c_str())){
  while (!virtual_thing.connect(virtual_thing_name.c_str(),NULL,NULL,willTopic,willQoS,willRetain,willMessage,cleanSession)) {       
    Serial.print(virtual_thing.state());    
    Serial.print(".");
    delay(1000);
  }

it shows - 2 in serial monitor

4

OK this might be related to Can't connect with LWT Last Will and Testament · Issue #678 · knolleary/pubsubclient · GitHub

try to increase the size of the buffer size

5

Buffersize manipulation is not working.

Those guys in github left for ESP32 instead of solving for ESP8266 :zipper_mouth_face:

6

I suggest opening a GitHub issue then

7

Thanks for reaching out. I found the solution.

last will and testament message has to be in proper json

Because of the malformed message, aws iot didn't get connected in my case.

8

Thanks for sharing the solution

9

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