How many simultaneous/consecutive connections can an ESP8266 Webserver handle? - websocket

Question

So I'm using the ESP8266WebServer and ESP8266WiFiMulti libraries to run a webpage with websockets and I'm trying to figure out how many client connections I can have, and if there's any way to increase that connection limit?
Right now it seems that I can successfully create three connections from separate IPs, and then upon initiating the fourth connection, it fails (the server doesn't crash in the serial model, but the fourth connection won't load the webpage).
I've also noticed that if I refresh my own singular connection a certain number of times (inconsistent), it will fail to load the webpage as well. I haven't been able to decipher whether this has to do with there being too many consecutive connections in general or if I'm overtaxing the server by attempting to reconnect within too quick a timeframe?
In general though, it seems rather unstable and I could really use some assistance on figuring out why.
Here's my current code:
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <WebSocketsServer.h>
#include <Hash.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
static const char ssid[] = "********";
static const char password[] = "********";
MDNSResponder mdns;
static void writeLED(bool);
ESP8266WiFiMulti WiFiMulti;
IPAddress ipAddressTest = (99,99,99,99);
ESP8266WebServer server(80);
WebSocketsServer webSocket = WebSocketsServer(81);
uint8_t pageHitCounter = 0;
IPAddress ipAddressOne = (99,99,99,99);
IPAddress ipAddressTwo = (99,99,99,99);
IPAddress ipAddressThree = (99,99,99,99);
IPAddress ipAddressFour = (99,99,99,99);
uint8_t rxBuff[256];
uint8_t som = 0x11;
uint8_t eom = 0x12;
uint8_t subsys;
uint8_t receivedSubsys;
uint8_t rx_byte = 0x00;
uint8_t messageLength = 0;
uint8_t receivedMessageLength = 0;
uint8_t messageContent;
uint8_t serialCurrent;
int initialCounter = 0;
boolean messageBegun = false;
boolean messageInProgress = false;
int currNumRefresh = 0;
int currMicroC = 0;
int currMicroD = 0;
int currMicroE = 0;
int currPressureC = 0;
int currPressureD = 0;
int currPressureE = 0;
int currValveStatusNumC = 0;
int currValveStatusNumD = 0;
int currValveStatusNumE = 0;
int currFluid = 0;
char statusbuf[256];
char status[] = "";
int statusIndex = 0;
String valveStatusC = "Closed";
String valveTubePropsC = "175px solid #00ADEF";
String valveColorC = "red";
String valveStatusD = "Closed";
String valveTubePropsD = "175px solid #00ADEF";
String valveColorD = "red";
String valveStatusE = "Closed";
String valveTubePropsE = "175px solid #00ADEF";
String valveColorE = "red";
uint8_t currCountdown = 0;
long prevTimeCountdown = 0;
long countdownInterval = 1000;
long countdownPostInterval = 100;
bool countdownFlag = true;
bool teensyPOWER = false;
bool pumpPOWER = false;
bool teensyLED = false;
void switchPOWERon() {
//Serial.println("TEST POWER ON");
int powerStatusLength = 1;
subsys = 0x10;
//Account for the end of message
messageLength = powerStatusLength + 2;
messageContent = 1;
Serial.write(som);
Serial.write(messageLength);
Serial.write(subsys);
Serial.write(messageContent);
Serial.write(eom);
//Serial.println("");
//Serial.println("TURN POWER ON|");
//teensyLED = true;
} //end switchPOWERon
void switchPOWERoff() {
/*Very similar to switchPoweron(), removed for char space*/
} //end switchPOWERoff
void pumpPOWERon() {
//Serial.println("TEST POWER ON");
int pumpPowerStatusLength = 1;
subsys = 0x13;
//Account for the end of message
messageLength = pumpPowerStatusLength + 2;
messageContent = 1;
Serial.write(som);
Serial.write(messageLength);
Serial.write(subsys);
Serial.write(messageContent);
Serial.write(eom);
//Serial.println("");
//Serial.println("TURN POWER ON|");
//teensyLED = true;
} //end switchPOWERon
void pumpPOWERoff() {
/*Very similar to pumpPoweron(), removed for char space*/
} //end switchPOWERoff
void switchLEDon() {
//Serial.println("TEST LED ON");
int ledStatusLength = 1;
subsys = 0x14;
//Account for the end of message
messageLength = ledStatusLength + 2;
messageContent = 1;
Serial.write(som);
Serial.write(messageLength);
Serial.write(subsys);
Serial.write(messageContent);
Serial.write(eom);
//Serial.println("");
//Serial.println("TURN LED ON|");
//teensyLED = true;
} //end switchLEDon
void switchLEDoff() {
/*Very similar to switchLEDon(), removed for char space*/
} //end switchLEDoff
void statusUpdate(uint8_t num) {
//Valve C
if(currValveStatusNumC == 0)
{
valveColorC = "red";
valveTubePropsC = "175px solid #00ADEF";
valveStatusC = "Closed";
} //end if
else if(currValveStatusNumC == 1)
{
valveColorC = "green";
valveTubePropsC = "350px solid #00ADEF";
valveStatusC = "Open";
} //end else if
/*Valves D/E removed for char space, very similar to Valve C*/
String test = "";
test += currNumRefresh;
test += ",";
/*Preparing more variables to send to the webpage, removed for char space*/
test += ",";
test += ipAddressTest;
//Serial.print("TEST: ");
//Serial.println(ipAddressTest);
test.toCharArray(statusbuf, 256);
webSocket.sendTXT(num, statusbuf, strlen(statusbuf));
}
static const char PROGMEM INDEX_HTML[] = R"rawliteral(
<!DOCTYPE html>
<html>
<head>
<title>Adafruit HUZZAH ESP8266</title>
<style type='text/css'>
/*CSS removed to fit maximum number of allowed characters*/
</style>
<script>
var currPressureTest = 0;
var currFluidTest = 0;
function POWERswitch(){
var POWERswitchCheck = document.getElementById('switch1').checked;
if(POWERswitchCheck){
websock.send("teensyPOWERon");
}
else if(!POWERswitchCheck) {
websock.send("teensyPOWERoff");
}
}
function FLUSHbegin(){
websock.send("pumpPOWERon");
}
function FLUSHend(){
websock.send("pumpPOWERoff");
}
function LEDswitch(){
var LEDswitchCheck = document.getElementById('myonoffswitch').checked;
if(LEDswitchCheck){
websock.send("teensyLEDon");
}
else if(!LEDswitchCheck) {
websock.send("teensyLEDoff");
}
}
var websock;
var test = "open";
var webpageHitCounter = 20;
function start() {
websock = new WebSocket('ws://' + window.location.hostname + ':81/');
websock.onopen = function(evt) {
console.log('websock open');
statusUpdate();
};
websock.onclose = function(evt) {
console.log('websock close');
};
websock.onerror = function(evt) {
console.log(evt);
};
websock.onmessage = function(evt) {
console.log(evt);
var e = document.getElementById('ledstatus');
var te = document.getElementById('myonoffswitch');
var pe = document.getElementById('switch1');
if(evt.data === 'teensyPOWERon')
{
pe.checked = 'checked';
}
else if(evt.data === 'teensyPOWERoff')
{
pe.checked = '';
}
else if(evt.data === 'pumpPOWERon')
{
}
else if(evt.data === 'pumpPOWERoff')
{
}
else if(evt.data === 'teensyLEDon')
{
te.checked = 'checked';
}
else if(evt.data === 'teensyLEDoff')
{
te.checked = '';
}
else if(evt.data === 'Update Status')
{
}
else {
console.log('status event');
var totalStatus = evt.data;
var splitStatus = totalStatus.split(',');
//Num Refresh
document.getElementById("demo").innerHTML = splitStatus[0];
/*Setting more variables from splitStatus[], removed for char space*/
}
};
}
function statusUpdate() {
websock.send("Update Status");
setTimeout('statusUpdate()', 5000);
}
</script>
</head>
<body style='background-color:#4a4a4c;' onload="start();">
<div style='text-align:center;'>
<h1 style='text-decoration: underline; color:white;'>Adafruit HUZZAH ESP8266</h1>
</div>
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<div style="clear:both;"></div>
<div class='counterContainer'>
<span id="counterText" style="color:white;"></span>
</div>
<div id='adminControls' class='adminControlsRow'>
<h2>Administrator Controls</h2>
<div id='Newbtn' class='powerSwitchContainer'>
<h2>HHIO PTT Power</h2>
<span class="switch">
<span class="switch-border1">
<span class="switch-border2">
<input id="switch1" type="checkbox" onclick='POWERswitch()' checked />
<label for="switch1"></label>
<span class="switch-top"></span>
<span class="switch-shadow"></span>
<span class="switch-handle"></span>
<span class="switch-handle-left"></span>
<span class="switch-handle-right"></span>
<span class="switch-handle-top"></span>
<span class="switch-handle-bottom"></span>
<span class="switch-handle-base"></span>
<span class="switch-led switch-led-green">
<span class="switch-led-border">
<span class="switch-led-light">
<span class="switch-led-glow"></span>
</span>
</span>
</span>
<span class="switch-led switch-led-red">
<span class="switch-led-border">
<span class="switch-led-light">
<span class="switch-led-glow"></span>
</span>
</span>
</span>
</span>
</span>
</span>
</div>
<div class='flushBtnContainer'>
<h2>Fluid Reservoir</h2>
<button id='flushBtn' onmousedown="FLUSHbegin();" onmouseup="FLUSHend();">Flush</button>
</div>
</div>
<div style='background-color:#1E1E20; clear:both;'>
<h2 style='color: white;'>LED Controls</h2>
<div id='LEDbtn' class='onoffswitch'>
<input type='checkbox' name='onoffswitch' class='onoffswitch-checkbox' id='myonoffswitch' onclick='LEDswitch()'>
<label class='onoffswitch-label' for='myonoffswitch'>
<span class='onoffswitch-inner'></span>
<span class='onoffswitch-switch'></span>
</label>
</div>
</div>
<div style='background-color:#1E1E20; color: white;'>
<h2>Num Refresh Test</h2>
<div id="demo"><h2>Let WEBSOCKET change this text</h2></div>
</div>
<div class='headerRow'>
/*Headers removed for char space*/
</div>
<div class='microswitchRow'>
<div class="microswitchContainer">
<div class="microswitch white">
<input type="radio" name="switchC" class="microswitchRadio" id="switchOffC" checked>
<input type="radio" name="switchC" class="microswitchRadio" id="switchOnC">
<label for="switchOffC">Detached</label>
<label for="switchOnC">Attached</label>
<span class="toggle"></span>
</div>
</div>
<div class="microswitchContainer">
<div class="microswitch white">
<input type="radio" name="switchD" class="microswitchRadio" id="switchOffD" checked>
<input type="radio" name="switchD" class="microswitchRadio" id="switchOnD">
<label for="switchOffD">Detached</label>
<label for="switchOnD">Attached</label>
<span class="toggle"></span>
</div>
</div>
<div class="microswitchContainer">
<div class="microswitch white">
<input type="radio" name="switchE" class="microswitchRadio" id="switchOffE" checked>
<input type="radio" name="switchE" class="microswitchRadio" id="switchOnE">
<label for="switchOffE">Detached</label>
<label for="switchOnE">Attached</label>
<span class="toggle"></span>
</div>
</div>
</div>
<div class='pressureRow'>
<div class='pressureContainer'>
<div class='gauge-a'></div>
<div class='gauge-b'></div>
<div class='gauge-c'></div>
<div class='gauge-data'><h1 id='pressurePercentC'>0%</h1></div>
</div>
<div class='pressureContainer'>
<div class='gauge-a'></div>
<div class='gauge-b'></div>
<div class='gauge-d'></div>
<div class='gauge-data'><h1 id='pressurePercentD'>0%</h1></div>
</div>
<div class='pressureContainer'>
<div class='gauge-a'></div>
<div class='gauge-b'></div>
<div class='gauge-e'></div>
<div class='gauge-data'><h1 id='pressurePercentE'>0%</h1></div>
</div>
</div>
<div class='valveRow'>
<div class='valveContainer'>
<div class="valveTube-c"></div>
<div class="valve-c"></div>
<div class='valve-data'><h1 id='valveStatus-c'>Closed</h1></div>
</div>
<div class='valveContainer'>
<div class="valveTube-d"></div>
<div class="valve-d"></div>
<div class='valve-data'><h1 id='valveStatus-d'>Closed</h1></div>
</div>
<div class='valveContainer'>
<div class="valveTube-e"></div>
<div class="valve-e"></div>
<div class='valve-data'><h1 id='valveStatus-e'>Closed</h1></div>
</div>
</div>
<div class='fluidContainer'>
<meter class='fluidMeter' max='100' value='50' low='25' high='75' optimum='100'></meter>
<div class='fluid-data'><h1 id='fluidPercent'>0%</h1></div>
</div>
</body>
</html>
)rawliteral";
const int LEDPIN = 0;
// Current POWER status
bool POWERStatus;
// Current LED status
bool LEDStatus;
// Commands sent through Web Socket
/*command array declarations removed for char space*/
const char statusIdentifier[] = "Update Status";
void webSocketEvent(uint8_t num, WStype_t type, uint8_t * payload, size_t length)
{
//Serial.printf("webSocketEvent(%d, %d, ...)\r\n", num, type);
switch(type) {
case WStype_DISCONNECTED:
//Serial.printf("[%u] Disconnected!\r\n", num);
break;
case WStype_CONNECTED:
{
IPAddress ip = webSocket.remoteIP(num);
//Serial.printf("[%u] Connected from %d.%d.%d.%d url: %s\r\n", num, ip[0], ip[1], ip[2], ip[3], payload);
// Send the current LED status
if (LEDStatus) {
webSocket.sendTXT(num, LEDON, strlen(LEDON));
}
else if(!LEDStatus) {
webSocket.sendTXT(num, LEDOFF, strlen(LEDOFF));
}
else if(teensyPOWER) {
webSocket.sendTXT(num, teensyPOWERON, strlen(teensyPOWERON));
}
else if(!teensyPOWER) {
webSocket.sendTXT(num, teensyPOWEROFF, strlen(teensyPOWEROFF));
}
else if(pumpPOWER) {
webSocket.sendTXT(num, teensyPOWERON, strlen(teensyPOWERON));
}
else if(!pumpPOWER) {
webSocket.sendTXT(num, pumpPOWEROFF, strlen(pumpPOWEROFF));
}
else if(teensyLED) {
webSocket.sendTXT(num, teensyLEDON, strlen(teensyLEDON));
}
else if(!teensyLED) {
webSocket.sendTXT(num, teensyLEDOFF, strlen(teensyLEDOFF));
}
}
break;
case WStype_TEXT:
//Serial.printf("[%u] get Text: %s\r\n", num, payload);
if (strcmp(LEDON, (const char *)payload) == 0) {
writeLED(true);
}
else if (strcmp(LEDOFF, (const char *)payload) == 0) {
writeLED(false);
}
else if(strcmp(teensyPOWERON, (const char *)payload) == 0) {
switchPOWERon();
}
else if(strcmp(teensyPOWEROFF, (const char *)payload) == 0) {
switchPOWERoff();
}
else if(strcmp(pumpPOWERON, (const char *)payload) == 0) {
pumpPOWERon();
}
else if(strcmp(pumpPOWEROFF, (const char *)payload) == 0) {
pumpPOWERoff();
}
else if(strcmp(teensyLEDON, (const char *)payload) == 0) {
switchLEDon();
}
else if(strcmp(teensyLEDOFF, (const char *)payload) == 0) {
switchLEDoff();
}
else if(strcmp(statusIdentifier, (const char *)payload) == 0) {
statusUpdate(num);
}
else {
//Serial.println("Unknown command");
}
// send data to all connected clients
webSocket.broadcastTXT(payload, length);
break;
case WStype_BIN:
//Serial.printf("[%u] get binary length: %u\r\n", num, length);
hexdump(payload, length);
// echo data back to browser
webSocket.sendBIN(num, payload, length);
break;
default:
//Serial.printf("Invalid WStype [%d]\r\n", type);
break;
}
}
void handleRoot()
{
server.send(200, "text/html", INDEX_HTML);
if(ipAddressTest != (0,0,0,0))
{
if(ipAddressOne == (99,99,99,99))
{
ipAddressOne = ipAddressTest;
pageHitCounter++;
//server.send(200, "text/html", INDEX_HTML);
Serial.print("1st NEW IP: ");
Serial.println(ipAddressTest);
}
else if(ipAddressTwo == (99,99,99,99))
{
if(ipAddressOne == ipAddressTest)
{
Serial.print("Old Connection-1 currently connected; Current Connection: ");
Serial.println(ipAddressTest);
//server.send(200, "text/html", INDEX_HTML);
}
else
{
ipAddressTwo = ipAddressTest;
pageHitCounter++;
//server.send(200, "text/html", INDEX_HTML);
Serial.print("2nd NEW IP: ");
Serial.println(ipAddressTest);
}
}
else if(ipAddressThree == (99,99,99,99))
{
if(ipAddressOne == ipAddressTest || ipAddressTwo == ipAddressTest)
{
Serial.print("Old Connection-2 currently connected; Current Connection: ");
Serial.println(ipAddressTest);
//server.send(200, "text/html", INDEX_HTML);
}
else
{
ipAddressThree = ipAddressTest;
pageHitCounter++;
//server.send(200, "text/html", INDEX_HTML);
Serial.print("3rd NEW IP: ");
Serial.println(ipAddressTest);
}
}
else if(ipAddressFour == (99,99,99,99))
{
if(ipAddressOne == ipAddressTest || ipAddressTwo == ipAddressTest || ipAddressThree == ipAddressTest)
{
Serial.println("Old Connection-3 currently connected; Current Connection: ");
Serial.println(ipAddressTest);
//server.send(200, "text/html", INDEX_HTML);
}
else
{
ipAddressFour = ipAddressTest;
pageHitCounter++;
//server.send(200, "text/html", INDEX_HTML);
Serial.print("4th NEW IP: ");
Serial.println(ipAddressTest);
}
}
else
{
if(ipAddressOne == ipAddressTest || ipAddressTwo == ipAddressTest || ipAddressThree == ipAddressTest || ipAddressFour == ipAddressTest)
{
Serial.println("Old Connection-4 currently connected; Current Connection: ");
Serial.println(ipAddressTest);
//server.send(200, "text/html", INDEX_HTML);
}
else
{
Serial.print("Too many connections! Attempting to Connect: ");
Serial.println(ipAddressTest);
}
}
}
}
void handleNotFound()
{
String message = "File Not Found\n\n";
message += "URI: ";
message += server.uri();
message += "\nMethod: ";
message += (server.method() == HTTP_GET)?"GET":"POST";
message += "\nArguments: ";
message += server.args();
message += "\n";
for (uint8_t i=0; i<server.args(); i++){
message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
}
server.send(404, "text/plain", message);
}
static void writeLED(bool LEDon)
{
LEDStatus = LEDon;
// Note inverted logic for Adafruit HUZZAH board
if (LEDon) {
digitalWrite(LEDPIN, 0);
}
else {
digitalWrite(LEDPIN, 1);
}
}
void setup()
{
pinMode(LEDPIN, OUTPUT);
writeLED(false);
Serial.begin(115200);
//Serial.setDebugOutput(true);
Serial.println();
Serial.println();
Serial.println();
currCountdown = 4;
for(uint8_t t = 4; t > 0; t--) {
unsigned long currTime = millis();
if(countdownFlag == true)
{
Serial.printf("[SETUP] BOOT WAIT %d...\r\n", t);
Serial.flush();
countdownFlag = false;
}
if(currTime - prevTimeCountdown > countdownInterval)
{
prevTimeCountdown = currTime;
countdownFlag = true;
} //end if
else
{
t++;
} //end else
} //end for
WiFiMulti.addAP(ssid, password);
/*
prevTimeCountdown = 0;
countdownFlag = true;
*/
while(WiFiMulti.run() != WL_CONNECTED) {
/*
unsigned long currTime = millis();
if(countdownFlag == true)
{
Serial.print(".");
countdownFlag = false;
} //end if
if(currTime - prevTimeCountdown > countdownInterval)
{
prevTimeCountdown = currTime;
countdownFlag = true;
} //end if
*/
Serial.print(".");
delay(1000);
} //end while
Serial.println("");
Serial.print("Connected to ");
Serial.println(ssid);
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
if (mdns.begin("espWebSock", WiFi.localIP())) {
Serial.println("MDNS responder started");
mdns.addService("http", "tcp", 80);
mdns.addService("ws", "tcp", 81);
}
else {
Serial.println("MDNS.begin failed");
}
Serial.print("Connect to http://espWebSock.local or http://");
Serial.println(WiFi.localIP());
server.on("/", handleRoot);
server.onNotFound(handleNotFound);
server.begin();
webSocket.begin();
webSocket.onEvent(webSocketEvent);
}
void loop()
{
//Communication Protocol
if(Serial.available() > 0)
{
//Serial.print("SERIAL.AVAILABLE: ");
//Serial.println(Serial.available());
if(initialCounter == 0)
{
rx_byte = Serial.read();
/*
//Print Start of Message
Serial.print("0x");
if(rx_byte<0x10)
{
Serial.print("0");
}
Serial.println(rx_byte, HEX);
*/
//Serial.println(rx_byte, BIN);
//Serial.println(rx_byte);
initialCounter++;
}
if((!messageBegun) && (rx_byte == som))
{
messageBegun = true;
//Serial.println("MESSAGE BEGUN TRUE");
} //end if (messageInProgress && rx_byte)
if((messageBegun) && (!messageInProgress))
{
serialCurrent = Serial.available();
if(serialCurrent > 0)
{
receivedMessageLength = (uint8_t)Serial.read();
/*
Serial.print("MESSAGE LENGTH: ");
Serial.println(receivedMessageLength);
*/
messageBegun = false;
messageInProgress = true;
//Serial.println("MESSAGE IN PROGRESS TRUE");
} //end if (serialCurrent)
} //end if (messageBegun && messageInProgress)
if(messageInProgress)
{
serialCurrent = Serial.available();
if(serialCurrent >= receivedMessageLength)
{
Serial.readBytes(rxBuff, receivedMessageLength);
if((byte)rxBuff[receivedMessageLength-1] != eom)
{
//Serial.println("ERROR");
//Serial.write(Serial.read());
} //end if (rxBuff != eom)
else
{
messageInProgress = false;
for(int i=0; i<receivedMessageLength; i++)
{
if(rxBuff[i] == eom)
{
/*
//Print End of Message
Serial.print("0x");
if(rx_byte<0x10)
{
Serial.print("0");
}
Serial.println(rxBuff[i], HEX);
*/
initialCounter = 0;
receivedMessageLength = 0;
} //end if
else if(i == 0)
{
receivedSubsys = rxBuff[i];
/*
//Print Subsystem
Serial.print("0x");
if(rx_byte<0x10)
{
Serial.print("0");
}
Serial.println(rxBuff[i], HEX);
*/
} //end if
else
{
if(receivedSubsys == 0x14)
{
currNumRefresh = rxBuff[i];
} //end if
/*Other subsystems removed for char space*/
} //end else
} //end if (serialCurrent)
} //end if (messageInProgress)
} //end if (Serial.available)
webSocket.loop();
ipAddressTest = server.handleClient();
}
P.S. I slightly modified ESP8266WebServer.cpp's handleClient() function to return the current IP address in order to track individual users, however sometimes I get 0.0.0.0 as an IP address and I don't know why or how to tell if that IP is a new IP or not.

Answer 1

I think Espressif documentation suggests a max of 5 UDP/TCP connections, that's what everyone always mentions anyways. I'd look it up but I'm behind a firewall right now :)
You don't mention which environment you are using, but I'm guessing Arduino based.
I don't know why you hit a limit at 3 instead of 5, could it be you're using connections for other protocols? I'm not sure what the MDNS stuff does, so maybe something in that. Also your browser could possibly be opening more connections then you expect (debug with browser debug functionality, e.g. f12? on most).
As usual, minimizing your code to the smallest example will help, try just the webserver, and see if you get closer to 5 :)

Answer 2

you must be careful with the size of the files you upload with FS.h. depending on the size some problems are generated when generating the page

Answer 3

Alright so I seem to have solved the issue by using the FS.h library and having an actual filesystem with directories where I can have actual html/css/js files and what not. This seems to have solved the stability issues.