How do various loops WebServer example work?

My question is what is the best place to put other than Net tasks.
I am showing data from serial port in a simple web page. Now I use millis() to simulate serial data.
I have a slightly modified WebServer sketch running on a Duemilanove. Currently it seems to work.

/*
  Web Server

 A simple web server that shows the value of the analog input pins.
 using an Arduino Wiznet Ethernet shield.

 Circuit:
 * Ethernet shield attached to pins 10, 11, 12, 13
 * Analog inputs attached to pins A0 through A5 (optional)

 created 18 Dec 2009
 by David A. Mellis
 modified 9 Apr 2012
 by Tom Igoe
 modified 02 Sept 2015
 by Arturo Guadalupi
 WebServeroma.ino
 16.2.2022
 */

#include <SPI.h>
#include <Ethernet.h>
unsigned long previousMillis, currentMillis;
char str[10];
int number;
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 1, 177);

// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);

void setup() {
  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet

  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  Serial.println("Ethernet WebServer Example");
 Serial.println("WebServeroma.ino");
  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip);

  // Check for Ethernet hardware present
  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); // do nothing, no point running without Ethernet hardware
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
  }

  // start the server
  server.begin();
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());

  number=0;
  itoa(number,str,10);
   //Serial.write(str);
  currentMillis=millis();
}


void loop() {
  // listen for incoming clients
  EthernetClient client = server.available();
  if (client) {
currentMillis=millis();
if (currentMillis - previousMillis >= 10000) {
    //Serial.write("gff ");  
  previousMillis=currentMillis;
  number++;
    itoa(number,str,10);
   Serial.write(str);
}
  
    Serial.println("new client");
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
  //  sprintf(str, "%f", number);  
      if (client.available()) {
        char c = client.read();
       // Serial.write(c);
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println();
          client.println("<!DOCTYPE HTML>");
          client.println("<html>");
          client.println(str); 
             //Serial.write(str);         
            client.println("<br />");
       
          client.println("</html>");
          break;
        }
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    // close the connection:
    client.stop();
    Serial.println("client disconnected");
  }
}

In loop() I think. Did I understand the question?

Please click Tools->Auto-format before posting your code next time.

I think you did, but did you notice that my own code is mainly in if (client) loop.
Edit: Serial.Write is for debugging.

Here is code better formatted.

/*
  Web Server

  A simple web server that shows the value of the analog input pins.
  using an Arduino Wiznet Ethernet shield.

  Circuit:
   Ethernet shield attached to pins 10, 11, 12, 13
   Analog inputs attached to pins A0 through A5 (optional)

  created 18 Dec 2009
  by David A. Mellis
  modified 9 Apr 2012
  by Tom Igoe
  modified 02 Sept 2015
  by Arturo Guadalupi
  WebServeroma.ino
  16.2.2022
*/

#include <SPI.h>
#include <Ethernet.h>
unsigned long previousMillis, currentMillis;
char str[10];
int number;
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 1, 177);

// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);

void setup() {
  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet

  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  Serial.println("Ethernet WebServer Example");
  Serial.println("WebServeroma.ino");
  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip);

  // Check for Ethernet hardware present
  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); // do nothing, no point running without Ethernet hardware
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
  }

  // start the server
  server.begin();
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());

  number = 0;
  itoa(number, str, 10);
  //Serial.write(str);
  currentMillis = millis();
}


void loop() {
  // listen for incoming clients
  EthernetClient client = server.available();
  if (client) {
    currentMillis = millis();
    if (currentMillis - previousMillis >= 10000) {
      //Serial.write("gff ");
      previousMillis = currentMillis;
      number++;
      itoa(number, str, 10);
      Serial.write(str);
    }

    Serial.println("new client");
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      //  sprintf(str, "%f", number);
      if (client.available()) {
        char c = client.read();
        // Serial.write(c);
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println();
          client.println("<!DOCTYPE HTML>");
          client.println("<html>");
          client.println(str);
          //Serial.write(str);
          client.println("<br />");

          client.println("</html>");
          break;
        }
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    // close the connection:
    client.stop();
    Serial.println("client disconnected");
  }
}

1 Like

What do you mean by "if (client) loop" ? Did you mean

while (client.connected()) {

?

The whole code is in post 4, but below is the part I am talking about.
My code is in variable declaration, and in lines 73-76, 84-90, and in line 113.

There is no loop in that part, so maybe I have misunderstood what you meant.

You asked

I said put them in loop(). Did you understand what I meant?

void loop() {
  // <--- Here, for example

  // listen for incoming clients
  EthernetClient client = server.available();
  if (client) {
    ...
    client.stop();
    Serial.println("client disconnected");
  }
  // <--- or here
}

Yes, it looks like I misunderstood your meaning. I'll move the code tomorrow, it is getting late here.

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