ESP8266_Temperature.ino

/*
 Sketch which publishes temperature data from a DS1820 sensor to a MQTT topic.

 This sketch goes in deep sleep mode once the temperature has been sent to the MQTT
 topic and wakes up periodically (configure SLEEP_DELAY_IN_SECONDS accordingly).

 Hookup guide:
 - connect D0 pin to RST pin in order to enable the ESP8266 to wake up periodically
 - DS18B20:
     + connect VCC (3.3V) to the appropriate DS18B20 pin (VDD)
     + connect GND to the appopriate DS18B20 pin (GND)
     + connect D4 to the DS18B20 data pin (DQ)
     + connect a 4.7K resistor between DQ and VCC.
*/

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <Streaming.h>

#define SLEEP_DELAY_IN_SECONDS  30
#define ONE_WIRE_BUS            D4      // DS18B20 pin

const char* ssid = "<YOUR_WIFI_NETWORK>";
const char* password = "<YOUR_WIFI_PASSWORD>";

const char* mqtt_server = "<MQTT_BROKER_IP_ADDRESS>";
const char* mqtt_username = "<MQTT_BROKER_USERNAME>";
const char* mqtt_password = "<MQTT_BROKER_PASSWORD>";
const char* mqtt_topic = "sensors/test/temperature";

WiFiClient espClient;
PubSubClient client(espClient);

OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature DS18B20(&oneWire);

char temperatureString[6];

void setup() {
  // setup serial port
  Serial.begin(115200);

  // setup WiFi
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  // setup OneWire bus
  DS18B20.begin();
}

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP8266Client", mqtt_username, mqtt_password)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

float getTemperature() {
  Serial << "Requesting DS18B20 temperature..." << endl;
  float temp;
  do {
    DS18B20.requestTemperatures(); 
    temp = DS18B20.getTempCByIndex(0);
    delay(100);
  } while (temp == 85.0 || temp == (-127.0));
  return temp;
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  float temperature = getTemperature();
  // convert temperature to a string with two digits before the comma and 2 digits for precision
  dtostrf(temperature, 2, 2, temperatureString);
  // send temperature to the serial console
  Serial << "Sending temperature: " << temperatureString << endl;
  // send temperature to the MQTT topic
  client.publish(mqtt_topic, temperatureString);

  Serial << "Closing MQTT connection..." << endl;
  client.disconnect();

  Serial << "Closing WiFi connection..." << endl;
  WiFi.disconnect();

  delay(100);

  Serial << "Entering deep sleep mode for " << SLEEP_DELAY_IN_SECONDS << " seconds..." << endl;
  ESP.deepSleep(SLEEP_DELAY_IN_SECONDS * 1000000, WAKE_RF_DEFAULT);
  //ESP.deepSleep(10 * 1000, WAKE_NO_RFCAL);
  delay(500);   // wait for deep sleep to happen
}

I have my local MQTT server and it works quite well.

So I am a newbie in Arduino and .ino, so please do not presume I know the obvious.

So next step was to introduce my NodeMCU units to my broker. This .ino appeared to be EXACTLY what I would need so I downloaded it and started to update the SSID and PW IP etc. -after installing the libraries I though was the correct ones.
When Verifying the code I get error messages so I assume I have picked the incorrect libraries.

Please educate me: How do I know which of the X-number of available libraries I should use?
It appears that some libraries has other imbedded libraries as verify fail as e.g arWiFi is not available, then after adding that, "no matching function for call to 'PubSubClient::PubSubClient(WiFiClient&)'"

Obviously I am doing something wrong.

Could you please give me some pointers