AsyncWebServer_STM32

Important Change from v1.5.0
Important Note from v1.6.0
Table of contents
Why do we need this AsyncWebServer_STM32 library
- Features
- Why Async is better
- Currently supported Boards
Changelog
Prerequisites
Installation
- Use Arduino Library Manager
- Manual Install
- VS Code & PlatformIO
Packages' Patches
- 1. For STM32 boards to use LAN8720
- 2. For STM32 boards to use Serial1
Important things to remember
Principles of operation
- The Async Web server
- Request Life Cycle
- Rewrites and how do they work
- Handlers and how do they work
- Responses and how do they work
- Template processing
Request Variables
- Common Variables
- Headers
- GET, POST and FILE parameters
- JSON body handling with ArduinoJson
Responses
- Redirect to another URL
- Basic response with HTTP Code
- Basic response with HTTP Code and extra headers
- Basic response with string content
- Basic response with string content and extra headers
- Respond with content coming from a Stream
- Respond with content coming from a Stream and extra headers
- Respond with content coming from a Stream containing templates
- Respond with content coming from a Stream containing templates and extra headers
- Respond with content using a callback
- Respond with content using a callback and extra headers
- Respond with content using a callback containing templates
- Respond with content using a callback containing templates and extra headers
- Chunked Response
- Chunked Response containing templates
- Print to response
- ArduinoJson Basic Response
- ArduinoJson Advanced Response
Param Rewrite With Matching
Using filters
Bad Responses
- Respond with content using a callback without content length to HTTP/1.0 clients
Async WebSocket Plugin
- Async WebSocket Event
- Methods for sending data to a socket client
- Direct access to web socket message buffer
- Limiting the number of web socket clients
Async Event Source Plugin
- Setup Event Source on the server
- Setup Event Source in the browser
Remove handlers and rewrites
Setting up the server
- Setup global and class functions as request handlers
- Methods for controlling websocket connections
- Adding Default Headers
- Path variable
HOWTO use STM32F4 with LAN8720
- 1. Wiring
- 2. HOWTO program using STLink V-2 or V-3
- 3. HOWTO use Serial Port for Debugging
Examples
- 1. For LAN8742A
- 2. For LAN8720
Example Async_AdvancedWebServer
Debug Terminal Output Samples
- 1. AsyncMultiWebServer_STM32 on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library
- 2. WebClient on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library
- 3. MQTTClient_Auth on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library
- 4. MQTTClient_Basic on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library
- 5. MQTT_ThingStream on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library
- 6. MQTTClient_Auth_LAN8720 on BLACK_F407VE using LAN8720 Ethernet and STM32Ethernet Library
- 7. Async_AdvancedWebServer_LAN8720 on BLACK_F407VE using LAN8720 Ethernet and STM32Ethernet Library
- 8. AsyncMultiWebServer_STM32_LAN8720 on BLACK_F407VE using LAN8720 Ethernet and STM32Ethernet Library
- 9. Async_AdvancedWebServer_favicon on NUCLEO_F767ZI with LAN8742A built-in Ethernet
- 10. Async_AdvancedWebServer_MemoryIssues_Send_CString on NUCLEO_F767ZI with LAN8742A built-in Ethernet
- 11. Async_AdvancedWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet
- 12. AsyncWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Debug
Troubleshooting
Issues
TO DO
DONE
Contributions and Thanks
Contributing
License
Copyright

Important Change from v1.5.0

For Generic STM32F4 series boards, such as STM32F407VE, using LAN8720, please use STM32 core v2.2.0 as breaking core v2.3.0 creates the compile error. Will fix in the near future.

Important Note from v1.6.0

The new v1.6.0+ has added a new and powerful feature to permit using CString to save heap to send very large data.

Check the marvelleous PRs of @salasidis in Portenta_H7_AsyncWebServer library

request->send(200, textPlainStr, jsonChartDataCharStr); - Without using String Class - to save heap #8
All memmove() removed - string no longer destroyed #11

and these new examples

Async_AdvancedWebServer_MemoryIssues_Send_CString
Async_AdvancedWebServer_MemoryIssues_SendArduinoString

If using Arduino String, to send a buffer around 5,5 KBytes, the used Max Heap is around 48,716 bytes

If using CString in regular memory, with the much larger 31 KBytes, the used Max Heap is around 42,952 bytes

This is very critical in use-cases where sending very large data is necessary, without heap-allocation-error.

The traditional function used to send Arduino String is

AsyncWebServer_STM32/src/AsyncWebServer_STM32.h

Line 424 in c14f228

    
           void send(int code, const String& contentType = String(), const String& content = String());

void send(int code, const String& contentType = String(), const String& content = String());

such as

request->send(200, textPlainStr, ArduinoStr);

The required additional HEAP is about 2 times of the String size

To use CString with copying while sending. Use function

AsyncWebServer_STM32/src/AsyncWebServer_STM32.h

Line 425 in c14f228

    
           void send(int code, const String& contentType, const char *content, bool copyingSend = true);    // RSMOD

void send(int code, const String& contentType, const char *content, bool copyingSend = true);    // RSMOD

such as

request->send(200, textPlainStr, cStr);

The required additional HEAP is also about 2 times of the CString size because of unnecessary copies of the CString in HEAP. Avoid this unefficient way.

To use CString without copying while sending. Use function

AsyncWebServer_STM32/src/AsyncWebServer_STM32.h

Line 425 in c14f228

    
           void send(int code, const String& contentType, const char *content, bool copyingSend = true);    // RSMOD

void send(int code, const String& contentType, const char *content, bool copyingSend = true);    // RSMOD

such as

request->send(200, textPlainStr, cStr, false);

The required additional HEAP is about 1 times of the CString size. This way is the best and most efficient way to use by avoiding of unnecessary copies of the CString in HEAP

Why do we need this AsyncWebServer_STM32 library

Features

This library is based on, modified from:

Hristo Gochkov's ESPAsyncWebServer

to apply the better and faster asynchronous feature of the powerful ESPAsyncWebServer Library into STM32F/L/H/G/WB/MP1 boards using LAN8720 or built-in LAN8742A Ethernet.

Why Async is better

Using asynchronous network means that you can handle more than one connection at the same time
You are called once the request is ready and parsed
When you send the response, you are immediately ready to handle other connections while the server is taking care of sending the response in the background
Speed is OMG
Easy to use API, HTTP Basic and Digest MD5 Authentication (default), ChunkedResponse
Easily extensible to handle any type of content
Supports Continue 100
Async WebSocket plugin offering different locations without extra servers or ports
Async EventSource (Server-Sent Events) plugin to send events to the browser
URL Rewrite plugin for conditional and permanent url rewrites
ServeStatic plugin that supports cache, Last-Modified, default index and more
Simple template processing engine to handle templates

Currently supported Boards

STM32F/L/H/G/WB/MP1 boards with built-in Ethernet LAN8742A such as :

Nucleo-144 (F429ZI, F767ZI)
Discovery (STM32F746G-DISCOVERY)
All STM32 boards (STM32F/L/H/G/WB/MP1) with 32K+ Flash, with Built-in Ethernet
See EthernetWebServer_STM32 Support and Test Results

STM32F4/F7 boards using Ethernet LAN8720 such as :

Nucleo-144 (F429ZI, NUCLEO_F746NG, NUCLEO_F746ZG, NUCLEO_F756ZG)
Discovery (DISCO_F746NG)
STM32F4 boards (BLACK_F407VE, BLACK_F407VG, BLACK_F407ZE, BLACK_F407ZG, BLACK_F407VE_Mini, DIYMORE_F407VGT, FK407M1)

Prerequisites

Arduino IDE 1.8.19+ for Arduino.
Arduino Core for STM32 v2.3.0+ for STM32 boards.
STM32Ethernet library v1.3.0+ for built-in LAN8742A Ethernet on (Nucleo-144, Discovery).
LwIP library v2.1.2+ for built-in LAN8742A Ethernet on (Nucleo-144, Discovery).
STM32AsyncTCP library v1.0.1+ for built-in Ethernet on (Nucleo-144, Discovery). To install manually for Arduino IDE.

Installation

Use Arduino Library Manager

The best and easiest way is to use Arduino Library Manager. Search for AsyncWebServer_STM32, then select / install the latest version. You can also use this link for more detailed instructions.

Manual Install

Navigate to AsyncWebServer_STM32 page.
Download the latest release AsyncWebServer_STM32-master.zip.
Extract the zip file to AsyncWebServer_STM32-master directory
Copy the whole AsyncWebServer_STM32-master folder to Arduino libraries' directory such as ~/Arduino/libraries/.

VS Code & PlatformIO:

Install VS Code
Install PlatformIO
Install AsyncWebServer_STM32 library by using Library Manager. Search for AsyncWebServer_STM32 in Platform.io Author's Libraries
Use included platformio.ini file from examples to ensure that all dependent libraries will installed automatically. Please visit documentation for the other options and examples at Project Configuration File

Packages' Patches

1. For STM32 boards to use LAN8720

To use LAN8720 on some STM32 boards

Nucleo-144 (F429ZI, NUCLEO_F746NG, NUCLEO_F746ZG, NUCLEO_F756ZG)
Discovery (DISCO_F746NG)
STM32F4 boards (BLACK_F407VE, BLACK_F407VG, BLACK_F407ZE, BLACK_F407ZG, BLACK_F407VE_Mini, DIYMORE_F407VGT, FK407M1)

you have to copy the files stm32f4xx_hal_conf_default.h and stm32f7xx_hal_conf_default.h into STM32 stm32 directory (~/.arduino15/packages/STM32/hardware/stm32/2.3.0/system) to overwrite the old files.

Supposing the STM32 stm32 core version is 2.3.0. These files must be copied into the directory:

~/.arduino15/packages/STM32/hardware/stm32/2.3.0/system/STM32F4xx/stm32f4xx_hal_conf_default.h for STM32F4.
~/.arduino15/packages/STM32/hardware/stm32/2.3.0/system/STM32F7xx/stm32f7xx_hal_conf_default.h for Nucleo-144 STM32F7.

Whenever a new version is installed, remember to copy this file into the new version directory. For example, new version is x.yy.zz, these files must be copied into the corresponding directory:

~/.arduino15/packages/STM32/hardware/stm32/x.yy.zz/system/STM32F4xx/stm32f4xx_hal_conf_default.h
`~/.arduino15/packages/STM32/hardware/stm32/x.yy.zz/system/STM32F7xx/stm32f7xx_hal_conf_default.h

2. For STM32 boards to use Serial1

To use Serial1 on some STM32 boards without Serial1 definition (Nucleo-144 NUCLEO_F767ZI, Nucleo-64 NUCLEO_L053R8, etc.) boards, you have to copy the files STM32 variant.h into STM32 stm32 directory (~/.arduino15/packages/STM32/hardware/stm32/2.3.0). You have to modify the files corresponding to your boards, this is just an illustration how to do.

Supposing the STM32 stm32 core version is 2.3.0. These files must be copied into the directory:

~/.arduino15/packages/STM32/hardware/stm32/2.3.0/variants/NUCLEO_F767ZI/variant.h for Nucleo-144 NUCLEO_F767ZI.
~/.arduino15/packages/STM32/hardware/stm32/2.3.0/variants/NUCLEO_L053R8/variant.h for Nucleo-64 NUCLEO_L053R8.

Whenever a new version is installed, remember to copy this file into the new version directory. For example, new version is x.yy.zz, these files must be copied into the corresponding directory:

~/.arduino15/packages/STM32/hardware/stm32/x.yy.zz/variants/NUCLEO_F767ZI/variant.h
~/.arduino15/packages/STM32/hardware/stm32/x.yy.zz/variants/NUCLEO_L053R8/variant.h

Important things to remember

This is fully asynchronous server and as such does not run on the loop thread.
You can not use yield() or delay() or any function that uses them inside the callbacks
The server is smart enough to know when to close the connection and free resources
You can not send more than one response to a single request

Principles of operation

The Async Web server

Listens for connections
Wraps the new clients into Request
Keeps track of clients and cleans memory
Manages Rewrites and apply them on the request url
Manages Handlers and attaches them to Requests

Request Life Cycle

TCP connection is received by the server
The connection is wrapped inside Request object
When the request head is received (type, url, get params, http version and host), the server goes through all Rewrites (in the order they were added) to rewrite the url and inject query parameters, next, it goes through all attached Handlers (in the order they were added) trying to find one that canHandle the given request. If none are found, the default(catch-all) handler is attached.
The rest of the request is received, calling the handleUpload or handleBody methods of the Handler if they are needed (POST+File/Body)
When the whole request is parsed, the result is given to the handleRequest method of the Handler and is ready to be responded to
In the handleRequest method, to the Request is attached a Response object (see below) that will serve the response data back to the client
When the Response is sent, the client is closed and freed from the memory

Rewrites and how do they work

The Rewrites are used to rewrite the request url and/or inject get parameters for a specific request url path.
All Rewrites are evaluated on the request in the order they have been added to the server.
The Rewrite will change the request url only if the request url (excluding get parameters) is fully match the rewrite url, and when the optional Filter callback return true.
Setting a Filter to the Rewrite enables to control when to apply the rewrite, decision can be based on request url, http version, request host/port/target host, get parameters or the request client's localIP or remoteIP.
The Rewrite can specify a target url with optional get parameters, e.g. /to-url?with=params

Handlers and how do they work

The Handlers are used for executing specific actions to particular requests
One Handler instance can be attached to any request and lives together with the server
Setting a Filter to the Handler enables to control when to apply the handler, decision can be based on request url, http version, request host/port/target host, get parameters or the request client's localIP or remoteIP.
The canHandle method is used for handler specific control on whether the requests can be handled and for declaring any interesting headers that the Request should parse. Decision can be based on request method, request url, http version, request host/port/target host and get parameters
Once a Handler is attached to given Request (canHandle returned true) that Handler takes care to receive any file/data upload and attach a Response once the Request has been fully parsed
Handlers are evaluated in the order they are attached to the server. The canHandle is called only if the Filter that was set to the Handler return true.
The first Handler that can handle the request is selected, not further Filter and canHandle are called.

Responses and how do they work

The Response objects are used to send the response data back to the client
The Response object lives with the Request and is freed on end or disconnect
Different techniques are used depending on the response type to send the data in packets returning back almost immediately and sending the next packet when this one is received. Any time in between is spent to run the user loop and handle other network packets
Responding asynchronously is probably the most difficult thing for most to understand
Many different options exist for the user to make responding a background task

Template processing

AsyncWebServer_STM32 contains simple template processing engine.
Template processing can be added to most response types.
Currently it supports only replacing template placeholders with actual values. No conditional processing, cycles, etc.
Placeholders are delimited with % symbols. Like this: %TEMPLATE_PLACEHOLDER%.
It works by extracting placeholder name from response text and passing it to user provided function which should return actual value to be used instead of placeholder.
Since it's user provided function, it is possible for library users to implement conditional processing and cycles themselves.
Since it's impossible to know the actual response size after template processing step in advance (and, therefore, to include it in response headers), the response becomes chunked.

Request Variables

Common Variables

request->version();       // uint8_t: 0 = HTTP/1.0, 1 = HTTP/1.1
request->method();        // enum:    HTTP_GET, HTTP_POST, HTTP_DELETE, HTTP_PUT, HTTP_PATCH, HTTP_HEAD, HTTP_OPTIONS
request->url();           // String:  URL of the request (not including host, port or GET parameters)
request->host();          // String:  The requested host (can be used for virtual hosting)
request->contentType();   // String:  ContentType of the request (not available in Handler::canHandle)
request->contentLength(); // size_t:  ContentLength of the request (not available in Handler::canHandle)
request->multipart();     // bool:    True if the request has content type "multipart"

Headers

//List all collected headers
int headers = request->headers();
int i;

for (i=0;i<headers;i++)
{
  AsyncWebHeader* h = request->getHeader(i);
  Serial.printf("HEADER[%s]: %s\n", h->name().c_str(), h->value().c_str());
}

//get specific header by name
if (request->hasHeader("MyHeader"))
{
  AsyncWebHeader* h = request->getHeader("MyHeader");
  Serial.printf("MyHeader: %s\n", h->value().c_str());
}

//List all collected headers (Compatibility)
int headers = request->headers();
int i;

for (i=0;i<headers;i++)
{
  Serial.printf("HEADER[%s]: %s\n", request->headerName(i).c_str(), request->header(i).c_str());
}

//get specific header by name (Compatibility)
if (request->hasHeader("MyHeader"))
{
  Serial.printf("MyHeader: %s\n", request->header("MyHeader").c_str());
}

GET, POST and FILE parameters

//List all parameters
int params = request->params();

for (int i=0;i<params;i++)
{
  AsyncWebParameter* p = request->getParam(i);
  
  if (p->isFile())
  { 
    //p->isPost() is also true
    Serial.printf("FILE[%s]: %s, size: %u\n", p->name().c_str(), p->value().c_str(), p->size());
  } 
  else if (p->isPost())
  {
    Serial.printf("POST[%s]: %s\n", p->name().c_str(), p->value().c_str());
  } 
  else 
  {
    Serial.printf("GET[%s]: %s\n", p->name().c_str(), p->value().c_str());
  }
}

//Check if GET parameter exists
if (request->hasParam("download"))
  AsyncWebParameter* p = request->getParam("download");

//Check if POST (but not File) parameter exists
if (request->hasParam("download", true))
  AsyncWebParameter* p = request->getParam("download", true);

//Check if FILE was uploaded
if (request->hasParam("download", true, true))
  AsyncWebParameter* p = request->getParam("download", true, true);

//List all parameters (Compatibility)
int args = request->args();

for (int i=0;i<args;i++)
{
  Serial.printf("ARG[%s]: %s\n", request->argName(i).c_str(), request->arg(i).c_str());
}

//Check if parameter exists (Compatibility)
if (request->hasArg("download"))
  String arg = request->arg("download");

JSON body handling with ArduinoJson

Endpoints which consume JSON can use a special handler to get ready to use JSON data in the request callback:

#include "AsyncJson.h"
#include "ArduinoJson.h"

AsyncCallbackJsonWebHandler* handler = new AsyncCallbackJsonWebHandler("/rest/endpoint", [](AsyncWebServerRequest *request, JsonVariant &json) 
{
  JsonObject& jsonObj = json.as<JsonObject>();
  // ...
});

server.addHandler(handler);

Responses

Redirect to another URL

//to local url
request->redirect("/login");

//to external url
request->redirect("http://esp8266.com");

Basic response with HTTP Code

request->send(404); //Sends 404 File Not Found

Basic response with HTTP Code and extra headers

AsyncWebServerResponse *response = request->beginResponse(404); //Sends 404 File Not Found
response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Basic response with string content

request->send(200, "text/plain", "Hello World!");

Basic response with string content and extra headers

AsyncWebServerResponse *response = request->beginResponse(200, "text/plain", "Hello World!");
response->addHeader("Server","AsyncWebServer");
request->send(response);

Respond with content coming from a Stream

//read 12 bytes from Serial and send them as Content Type text/plain
request->send(Serial, "text/plain", 12);

Respond with content coming from a Stream and extra headers

//read 12 bytes from Serial and send them as Content Type text/plain
AsyncWebServerResponse *response = request->beginResponse(Serial, "text/plain", 12);

response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Respond with content coming from a Stream containing templates

String processor(const String& var)
{
  if (var == "HELLO_FROM_TEMPLATE")
    return F("Hello world!");
    
  return String();
}

// ...

//read 12 bytes from Serial and send them as Content Type text/plain
request->send(Serial, "text/plain", 12, processor);

Respond with content coming from a Stream containing templates and extra headers

String processor(const String& var)
{
  if (var == "HELLO_FROM_TEMPLATE")
    return F("Hello world!");
  return String();
}

// ...

//read 12 bytes from Serial and send them as Content Type text/plain
AsyncWebServerResponse *response = request->beginResponse(Serial, "text/plain", 12, processor);

response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Respond with content using a callback

//send 128 bytes as plain text
request->send("text/plain", 128, [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //index equals the amount of bytes that have been already sent
  //You will not be asked for more bytes once the content length has been reached.
  //Keep in mind that you can not delay or yield waiting for more data!
  //Send what you currently have and you will be asked for more again
  return mySource.read(buffer, maxLen);
});

Respond with content using a callback and extra headers

//send 128 bytes as plain text
AsyncWebServerResponse *response = request->beginResponse("text/plain", 128, [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //index equals the amount of bytes that have been already sent
  //You will not be asked for more bytes once the content length has been reached.
  //Keep in mind that you can not delay or yield waiting for more data!
  //Send what you currently have and you will be asked for more again
  return mySource.read(buffer, maxLen);
});

response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Respond with content using a callback containing templates

String processor(const String& var)
{
  if (var == "HELLO_FROM_TEMPLATE")
    return F("Hello world!");
    
  return String();
}

// ...

//send 128 bytes as plain text
request->send("text/plain", 128, [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //index equals the amount of bytes that have been already sent
  //You will not be asked for more bytes once the content length has been reached.
  //Keep in mind that you can not delay or yield waiting for more data!
  //Send what you currently have and you will be asked for more again
  return mySource.read(buffer, maxLen);
}, processor);

Respond with content using a callback containing templates and extra headers

String processor(const String& var)
{
  if (var == "HELLO_FROM_TEMPLATE")
    return F("Hello world!");
    
  return String();
}

// ...

//send 128 bytes as plain text
AsyncWebServerResponse *response = request->beginResponse("text/plain", 128, [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //index equals the amount of bytes that have been already sent
  //You will not be asked for more bytes once the content length has been reached.
  //Keep in mind that you can not delay or yield waiting for more data!
  //Send what you currently have and you will be asked for more again
  return mySource.read(buffer, maxLen);
}, processor);

response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Chunked Response

Used when content length is unknown. Works best if the client supports HTTP/1.1

AsyncWebServerResponse *response = request->beginChunkedResponse("text/plain", [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //index equals the amount of bytes that have been already sent
  //You will be asked for more data until 0 is returned
  //Keep in mind that you can not delay or yield waiting for more data!
  return mySource.read(buffer, maxLen);
});

response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Chunked Response containing templates

Used when content length is unknown. Works best if the client supports HTTP/1.1

String processor(const String& var)
{
  if (var == "HELLO_FROM_TEMPLATE")
    return F("Hello world!");
    
  return String();
}

// ...

AsyncWebServerResponse *response = request->beginChunkedResponse("text/plain", [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //index equals the amount of bytes that have been already sent
  //You will be asked for more data until 0 is returned
  //Keep in mind that you can not delay or yield waiting for more data!
  return mySource.read(buffer, maxLen);
}, processor);

response->addHeader("Server","AsyncWebServer_STM32");
request->send(response);

Print to response

AsyncResponseStream *response = request->beginResponseStream("text/html");
response->addHeader("Server","AsyncWebServer_STM32");
response->printf("<!DOCTYPE html><html><head><title>Webpage at %s</title></head><body>", request->url().c_str());

response->print("<h2>Hello ");
response->print(request->client()->remoteIP());
response->print("</h2>");

response->print("<h3>General</h3>");
response->print("<ul>");
response->printf("<li>Version: HTTP/1.%u</li>", request->version());
response->printf("<li>Method: %s</li>", request->methodToString());
response->printf("<li>URL: %s</li>", request->url().c_str());
response->printf("<li>Host: %s</li>", request->host().c_str());
response->printf("<li>ContentType: %s</li>", request->contentType().c_str());
response->printf("<li>ContentLength: %u</li>", request->contentLength());
response->printf("<li>Multipart: %s</li>", request->multipart()?"true":"false");
response->print("</ul>");

response->print("<h3>Headers</h3>");
response->print("<ul>");

int headers = request->headers();

for (int i=0;i<headers;i++)
{
  AsyncWebHeader* h = request->getHeader(i);
  response->printf("<li>%s: %s</li>", h->name().c_str(), h->value().c_str());
}

response->print("</ul>");

response->print("<h3>Parameters</h3>");
response->print("<ul>");

int params = request->params();

for (int i=0;i<params;i++)
{
  AsyncWebParameter* p = request->getParam(i);
  
  if (p->isFile())
  {
    response->printf("<li>FILE[%s]: %s, size: %u</li>", p->name().c_str(), p->value().c_str(), p->size());
  } 
  else if (p->isPost())
  {
    response->printf("<li>POST[%s]: %s</li>", p->name().c_str(), p->value().c_str());
  } 
  else 
  {
    response->printf("<li>GET[%s]: %s</li>", p->name().c_str(), p->value().c_str());
  }
}

response->print("</ul>");

response->print("</body></html>");

//send the response last
request->send(response);

ArduinoJson Basic Response

This way of sending Json is great for when the result is below 4KB

#include "AsyncJson.h"
#include "ArduinoJson.h"

AsyncResponseStream *response = request->beginResponseStream("application/json");
DynamicJsonBuffer jsonBuffer;
JsonObject &root = jsonBuffer.createObject();
root["heap"] = ESP.getFreeHeap();
root["ssid"] = WiFi.SSID();
root.printTo(*response);

request->send(response);

ArduinoJson Advanced Response

This response can handle really large Json objects (tested to 40KB)

There isn't any noticeable speed decrease for small results with the method above

Since ArduinoJson does not allow reading parts of the string, the whole Json has to be passed every time a chunks needs to be sent, which shows speed decrease proportional to the resulting json packets

#include "AsyncJson.h"
#include "ArduinoJson.h"

AsyncJsonResponse * response = new AsyncJsonResponse();
response->addHeader("Server","AsyncWebServer");
JsonObject& root = response->getRoot();
root["IP"] = Ethernet.localIP();
response->setLength();

request->send(response);

Param Rewrite With Matching

It is possible to rewrite the request url with parameter matchg. Here is an example with one parameter: Rewrite for example "/radio/{frequence}" -> "/radio?f={frequence}"

class OneParamRewrite : public AsyncWebRewrite
{
  protected:

    String _urlPrefix;
    int _paramIndex;
    String _paramsBackup;

  public:

    OneParamRewrite(const char* from, const char* to)
      : AsyncWebRewrite(from, to)
    {

      _paramIndex = _from.indexOf('{');

      if ( _paramIndex >= 0 && _from.endsWith("}"))
      {
        _urlPrefix = _from.substring(0, _paramIndex);
        int index = _params.indexOf('{');

        if (index >= 0)
        {
          _params = _params.substring(0, index);
        }
      }
      else
      {
        _urlPrefix = _from;
      }

      _paramsBackup = _params;
    }

    bool match(AsyncWebServerRequest *request) override
    {
      if (request->url().startsWith(_urlPrefix))
      {
        if (_paramIndex >= 0)
        {
          _params = _paramsBackup + request->url().substring(_paramIndex);
        }
        else
        {
          _params = _paramsBackup;
        }

        return true;

      }
      else
      {
        return false;
      }
    }
};

Usage:

server.addRewrite( new OneParamRewrite("/radio/{frequence}", "/radio?f={frequence}") );

Using filters

Filters can be set to Rewrite or Handler in order to control when to apply the rewrite and consider the handler. A filter is a callback function that evaluates the request and return a boolean true to include the item or false to exclude it.

Bad Responses

Some responses are implemented, but you should not use them, because they do not conform to HTTP. The following example will lead to unclean close of the connection and more time wasted than providing the length of the content

Respond with content using a callback without content length to HTTP/1.0 clients

//This is used as fallback for chunked responses to HTTP/1.0 Clients
request->send("text/plain", 0, [](uint8_t *buffer, size_t maxLen, size_t index) -> size_t 
{
  //Write up to "maxLen" bytes into "buffer" and return the amount written.
  //You will be asked for more data until 0 is returned
  //Keep in mind that you can not delay or yield waiting for more data!
  return mySource.read(buffer, maxLen);
});

Async WebSocket Plugin

The server includes a web socket plugin which lets you define different WebSocket locations to connect to without starting another listening service or using different port

Async WebSocket Event

void onEvent(AsyncWebSocket * server, AsyncWebSocketClient * client, AwsEventType type, void * arg, uint8_t *data, size_t len)
{
  if (type == WS_EVT_CONNECT)
  {
    //client connected
    Serial.printf("ws[%s][%u] connect\n", server->url(), client->id());
    client->printf("Hello Client %u :)", client->id());
    client->ping();
  } 
  else if (type == WS_EVT_DISCONNECT)
  {
    //client disconnected
    Serial.printf("ws[%s][%u] disconnect: %u\n", server->url(), client->id());
  } 
  else if (type == WS_EVT_ERROR)
  {
    //error was received from the other end
    Serial.printf("ws[%s][%u] error(%u): %s\n", server->url(), client->id(), *((uint16_t*)arg), (char*)data);
  } 
  else if (type == WS_EVT_PONG)
  {
    //pong message was received (in response to a ping request maybe)
    Serial.printf("ws[%s][%u] pong[%u]: %s\n", server->url(), client->id(), len, (len)?(char*)data:"");
  } 
  else if (type == WS_EVT_DATA)
  {
    //data packet
    AwsFrameInfo * info = (AwsFrameInfo*)arg;
    
    if (info->final && info->index == 0 && info->len == len)
    {
      //the whole message is in a single frame and we got all of it's data
      Serial.printf("ws[%s][%u] %s-message[%llu]: ", server->url(), client->id(), (info->opcode == WS_TEXT)?"text":"binary", info->len);
      
      if (info->opcode == WS_TEXT)
      {
        data[len] = 0;
        Serial.printf("%s\n", (char*)data);
      } 
      else 
      {
        for (size_t i=0; i < info->len; i++)
        {
          Serial.printf("%02x ", data[i]);
        }
        
        Serial.printf("\n");
      }
      
      if (info->opcode == WS_TEXT)
        client->text("I got your text message");
      else
        client->binary("I got your binary message");
    } 
    else 
    {
      //message is comprised of multiple frames or the frame is split into multiple packets
      if (info->index == 0)
      {
        if (info->num == 0)
          Serial.printf("ws[%s][%u] %s-message start\n", server->url(), client->id(), (info->message_opcode == WS_TEXT)?"text":"binary");
          
        Serial.printf("ws[%s][%u] frame[%u] start[%llu]\n", server->url(), client->id(), info->num, info->len);
      }

      Serial.printf("ws[%s][%u] frame[%u] %s[%llu - %llu]: ", server->url(), client->id(), info->num, (info->message_opcode == WS_TEXT)?"text":"binary", info->index, info->index + len);
      
      if (info->message_opcode == WS_TEXT)
      {
        data[len] = 0;
        Serial.printf("%s\n", (char*)data);
      } 
      else 
      {
        for (size_t i=0; i < len; i++)
        {
          Serial.printf("%02x ", data[i]);
        }
        
        Serial.printf("\n");
      }

      if ((info->index + len) == info->len)
      {
        Serial.printf("ws[%s][%u] frame[%u] end[%llu]\n", server->url(), client->id(), info->num, info->len);
        
        if (info->final)
        {
          Serial.printf("ws[%s][%u] %s-message end\n", server->url(), client->id(), (info->message_opcode == WS_TEXT)?"text":"binary");
          
          if (info->message_opcode == WS_TEXT)
            client->text("I got your text message");
          else
            client->binary("I got your binary message");
        }
      }
    }
  }
}

Methods for sending data to a socket client

//Server methods
AsyncWebSocket ws("/ws");

//printf to a client
ws.printf((uint32_t)client_id, arguments...);

//printf to all clients
ws.printfAll(arguments...);

//send text to a client
ws.text((uint32_t)client_id, (char*)text);
ws.text((uint32_t)client_id, (uint8_t*)text, (size_t)len);

//send text to all clients
ws.textAll((char*)text);
ws.textAll((uint8_t*)text, (size_t)len);

//send binary to a client
ws.binary((uint32_t)client_id, (char*)binary);
ws.binary((uint32_t)client_id, (uint8_t*)binary, (size_t)len);
ws.binary((uint32_t)client_id, flash_binary, 4);

//send binary to all clients
ws.binaryAll((char*)binary);
ws.binaryAll((uint8_t*)binary, (size_t)len);

//HTTP Authenticate before switch to Websocket protocol
ws.setAuthentication("user", "pass");

//client methods
AsyncWebSocketClient * client;

//printf
client->printf(arguments...);

//send text
client->text((char*)text);
client->text((uint8_t*)text, (size_t)len);

//send binary
client->binary((char*)binary);
client->binary((uint8_t*)binary, (size_t)len);

Direct access to web socket message buffer

When sending a web socket message using the above methods a buffer is created. Under certain circumstances you might want to manipulate or populate this buffer directly from your application, for example to prevent unnecessary duplications of the data. This example below shows how to create a buffer and print data to it from an ArduinoJson object then send it.

void sendDataWs(AsyncWebSocketClient * client)
{
  DynamicJsonBuffer jsonBuffer;
  JsonObject& root = jsonBuffer.createObject();
  root["a"] = "abc";
  root["b"] = "abcd";
  root["c"] = "abcde";
  root["d"] = "abcdef";
  root["e"] = "abcdefg";
  size_t len = root.measureLength();
  
  AsyncWebSocketMessageBuffer * buffer = ws.makeBuffer(len); //  creates a buffer (len + 1) for you.
  
  if (buffer) 
  {
    root.printTo((char *)buffer->get(), len + 1);
    
    if (client) 
    {
        client->text(buffer);
    } 
    else 
    {
        ws.textAll(buffer);
    }
  }
}

Limiting the number of web socket clients

Browsers sometimes do not correctly close the websocket connection, even when the close() function is called in javascript. This will eventually exhaust the web server's resources and will cause the server to crash. Periodically calling the cleanClients() function from the main loop() function limits the number of clients by closing the oldest client when the maximum number of clients has been exceeded. This can called be every cycle, however, if you wish to use less power, then calling as infrequently as once per second is sufficient.

void loop()
{
  ws.cleanupClients();
}

Async Event Source Plugin

The server includes EventSource (Server-Sent Events) plugin which can be used to send short text events to the browser. Difference between EventSource and WebSockets is that EventSource is single direction, text-only protocol.

Setup Event Source on the server

AsyncWebServer server(80);
AsyncEventSource events("/events");

void setup()
{
  // setup ......
  events.onConnect([](AsyncEventSourceClient *client)
  {
    if (client->lastId())
    {
      Serial.printf("Client reconnected! Last message ID that it got is: %u\n", client->lastId());
    }
    
    //send event with message "hello!", id current millis
    // and set reconnect delay to 1 second
    client->send("hello!",NULL,millis(),1000);
  });
  
  //HTTP Basic authentication
  events.setAuthentication("user", "pass");
  server.addHandler(&events);
  // setup ......
}

void loop()
{
  if (eventTriggered)
  { 
    // your logic here
    //send event "myevent"
    events.send("my event content","myevent",millis());
  }
}

Setup Event Source in the browser

if (!!window.EventSource) 
{
  var source = new EventSource('/events');

  source.addEventListener('open', function(e) 
  {
    console.log("Events Connected");
  }, false);

  source.addEventListener('error', function(e) 
  {
    if (e.target.readyState != EventSource.OPEN) 
    {
      console.log("Events Disconnected");
    }
  }, false);

  source.addEventListener('message', function(e) 
  {
    console.log("message", e.data);
  }, false);

  source.addEventListener('myevent', function(e) 
  {
    console.log("myevent", e.data);
  }, false);
}

Remove handlers and rewrites

Server goes through handlers in same order as they were added. You can't simple add handler with same path to override them. To remove handler:

// save callback for particular URL path
auto handler = server.on("/some/path", [](AsyncWebServerRequest *request)
{
  //do something useful
});

// when you don't need handler anymore remove it
server.removeHandler(&handler);

// same with rewrites
server.removeRewrite(&someRewrite);

server.onNotFound([](AsyncWebServerRequest *request)
{
  request->send(404);
});

// remove server.onNotFound handler
server.onNotFound(NULL);

// remove all rewrites, handlers and onNotFound/onFileUpload/onRequestBody callbacks
server.reset();

Setting up the server

#include <LwIP.h>
#include <STM32Ethernet.h>
#include <AsyncWebServer_STM32.h>

// Enter a MAC address and IP address for your controller below.
#define NUMBER_OF_MAC      20

byte mac[][NUMBER_OF_MAC] =
{
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x01 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x02 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x03 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x04 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x05 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x06 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x07 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x08 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x09 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0A },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0B },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0C },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0D },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0E },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0F },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x10 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x11 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x12 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x13 },
  { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x14 },
};

// Select the IP address according to your local network
IPAddress ip(192, 168, 2, 232);

AsyncWebServer    server(80);

const int led = 13;

void handleRoot(AsyncWebServerRequest *request)
{
  digitalWrite(led, 1);
  request->send(200, "text/plain", String("Hello from AsyncWebServer_STM32 on ") + BOARD_NAME );
  digitalWrite(led, 0);
}

void handleNotFound(AsyncWebServerRequest *request)
{
  digitalWrite(led, 1);
  String message = "File Not Found\n\n";

  message += "URI: ";
  //message += server.uri();
  message += request->url();
  message += "\nMethod: ";
  message += (request->method() == HTTP_GET) ? "GET" : "POST";
  message += "\nArguments: ";
  message += request->args();
  message += "\n";

  for (uint8_t i = 0; i < request->args(); i++)
  {
    message += " " + request->argName(i) + ": " + request->arg(i) + "\n";
  }

  request->send(404, "text/plain", message);
  digitalWrite(led, 0);
}

void setup(void)
{
  pinMode(led, OUTPUT);
  digitalWrite(led, 0);

  Serial.begin(115200);
  while (!Serial && millis() < 5000);
  
  Serial.println("\nStart Async_HelloServer on " + String(BOARD_NAME));

  // start the ethernet connection and the server
  // Use random mac
  uint16_t index = millis() % NUMBER_OF_MAC;

  // Use Static IP
  //Ethernet.begin(mac[index], ip);
  // Use DHCP dynamic IP and random mac
  Ethernet.begin(mac[index]);

  server.on("/", HTTP_GET, [](AsyncWebServerRequest * request)
  {
    handleRoot(request);
  });

  server.on("/inline", [](AsyncWebServerRequest * request)
  {
    request->send(200, "text/plain", "This works as well");
  });

  server.onNotFound(handleNotFound);

  server.begin();

  Serial.print(F("HTTP EthernetWebServer is @ IP : "));
  Serial.println(Ethernet.localIP());
}

void loop(void)
{
}

Setup global and class functions as request handlers

#include <Arduino.h>

#include <LwIP.h>
#include <STM32Ethernet.h>
#include <AsyncWebServer_STM32.h>

#include <functional>

...

void handleRequest(AsyncWebServerRequest *request){}

class WebClass 
{
public :
  AsyncWebServer classWebServer = AsyncWebServer(81);

  WebClass(){};

  void classRequest (AsyncWebServerRequest *request){}

  void begin()
  {
    // attach global request handler
    classWebServer.on("/example", HTTP_ANY, handleRequest);

    // attach class request handler
    classWebServer.on("/example", HTTP_ANY, std::bind(&WebClass::classRequest, this, std::placeholders::_1));
  }
};

AsyncWebServer globalWebServer(80);
WebClass webClassInstance;

void setup() 
{
  // attach global request handler
  globalWebServer.on("/example", HTTP_ANY, handleRequest);

  // attach class request handler
  globalWebServer.on("/example", HTTP_ANY, std::bind(&WebClass::classRequest, webClassInstance, std::placeholders::_1));
}

void loop() 
{

}

Methods for controlling websocket connections

  // Disable client connections if it was activated
  if ( ws.enabled() )
    ws.enable(false);

  // enable client connections if it was disabled
  if ( !ws.enabled() )
    ws.enable(true);

Adding Default Headers

In some cases, such as when working with CORS, or with some sort of custom authentication system, you might need to define a header that should get added to all responses (including static, websocket and EventSource). The DefaultHeaders singleton allows you to do this.

Example:

DefaultHeaders::Instance().addHeader("Access-Control-Allow-Origin", "*");
webServer.begin();

NOTE: You will still need to respond to the OPTIONS method for CORS pre-flight in most cases. (unless you are only using GET)

This is one option:

webServer.onNotFound([](AsyncWebServerRequest *request) 
{
  if (request->method() == HTTP_OPTIONS) 
  {
    request->send(200);
  } 
  else 
  {
    request->send(404);
  }
});

Path variable

With path variable you can create a custom regex rule for a specific parameter in a route. For example we want a sensorId parameter in a route rule to match only an integer.

server.on("^\\/sensor\\/([0-9]+)$", HTTP_GET, [] (AsyncWebServerRequest *request) 
{
    String sensorId = request->pathArg(0);
});

NOTE: All regex patterns starts with ^ and ends with $

To enable the Path variable support, you have to define the buildflag -DASYNCWEBSERVER_REGEX.

For Arduino IDE create/update platform.local.txt:

Windows: C:\Users(username)\AppData\Local\Arduino15\packages\{espxxxx}\hardware\espxxxx\{version}\platform.local.txt

Linux: ~/.arduino15/packages/{espxxxx}/hardware/{espxxxx}/{version}/platform.local.txt

Add/Update the following line:

compiler.cpp.extra_flags=-DDASYNCWEBSERVER_REGEX

For platformio modify platformio.ini:

[env:myboard]
build_flags = -DASYNCWEBSERVER_REGEX

NOTE: By enabling ASYNCWEBSERVER_REGEX, <regex> will be included. This will add an 100k to your binary.

HOWTO use STM32F4 with LAN8720

1. Wiring

This is the Wiring for STM32F4 (BLACK_F407VE, etc.) using LAN8720

LAN8720 PHY	<--->	STM32F4
TX1	<--->	PB_13
TX_EN	<--->	PB_11
TX0	<--->	PB_12
RX0	<--->	PC_4
RX1	<--->	PC_5
nINT/RETCLK	<--->	PA_1
CRS	<--->	PA_7
MDIO	<--->	PA_2
MDC	<--->	PC_1
GND	<--->	GND
VCC	<--->	+3.3V

2. HOWTO program using STLink V-2 or V-3

Connect as follows. To program, use STM32CubeProgrammer or Arduino IDE with

U(S)ART Support: "Enabled (generic Serial)"
Upload Method : "STM32CubeProgrammer (SWD)"

STLink	<--->	STM32F4
SWCLK	<--->	SWCLK
SWDIO	<--->	SWDIO
RST	<--->	NRST
GND	<--->	GND
5v	<--->	5V

3. HOWTO use Serial Port for Debugging

Connect FDTI (USB to Serial) as follows:

FDTI	<--->	STM32F4
RX	<--->	TX=PA_9
TX	<--->	RX=PA_10
GND	<--->	GND

Examples

1. For LAN8742A

Async_AdvancedWebServer
AsyncFSBrowser_STM32
Async_HelloServer
Async_HelloServer2
Async_HttpBasicAuth
Async_PostServer
AsyncMultiWebServer_STM32
Async_RegexPatterns_STM32
Async_SimpleWebServer_STM32
MQTTClient_Auth
MQTTClient_Basic
MQTT_ThingStream
WebClient
WebClientRepeating
Async_AdvancedWebServer_favicon New
Async_AdvancedWebServer_MemoryIssues_SendArduinoString New
Async_AdvancedWebServer_MemoryIssues_Send_CString New
Async_AdvancedWebServer_SendChunked New
AsyncWebServer_SendChunked New

2. For LAN8720

Async_AdvancedWebServer_LAN8720
AsyncFSBrowser_STM32_LAN8720
Async_HelloServer_LAN8720
Async_HelloServer2_LAN8720
Async_HttpBasicAuth_LAN8720
AsyncMultiWebServer_STM32_LAN8720
Async_PostServer_LAN8720
Async_RegexPatterns_STM32_LAN8720
Async_SimpleWebServer_STM32_LAN8720
MQTTClient_Auth_LAN8720
MQTTClient_Basic_LAN8720
MQTT_ThingStream_LAN8720
WebClient_LAN8720
WebClientRepeating_LAN8720

Example Async_AdvancedWebServer

AsyncWebServer_STM32/examples/Async_AdvancedWebServer/Async_AdvancedWebServer.ino

Lines 52 to 287 in ea34316

    
           #if !( defined(STM32F0) || defined(STM32F1) || defined(STM32F2) || defined(STM32F3)  ||defined(STM32F4) || defined(STM32F7) || \ 
        
                  defined(STM32L0) || defined(STM32L1) || defined(STM32L4) || defined(STM32H7)  ||defined(STM32G0) || defined(STM32G4) || \ 
        
                  defined(STM32WB) || defined(STM32MP1) ) 
        
             #error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting. 
        
           #endif 
        
           #define _ASYNCWEBSERVER_STM32_LOGLEVEL_       4 
        
           #if defined(STM32F0) 
        
             #warning STM32F0 board selected 
        
             #define BOARD_TYPE  "STM32F0" 
        
           #elif defined(STM32F1) 
        
             #warning STM32F1 board selected 
        
             #define BOARD_TYPE  "STM32F1" 
        
           #elif defined(STM32F2) 
        
             #warning STM32F2 board selected 
        
             #define BOARD_TYPE  "STM32F2" 
        
           #elif defined(STM32F3) 
        
             #warning STM32F3 board selected 
        
             #define BOARD_TYPE  "STM32F3" 
        
           #elif defined(STM32F4) 
        
             #warning STM32F4 board selected 
        
             #define BOARD_TYPE  "STM32F4" 
        
           #elif defined(STM32F7) 
        
             #warning STM32F7 board selected 
        
             #define BOARD_TYPE  "STM32F7" 
        
           #elif defined(STM32L0) 
        
             #warning STM32L0 board selected 
        
             #define BOARD_TYPE  "STM32L0" 
        
           #elif defined(STM32L1) 
        
             #warning STM32L1 board selected 
        
             #define BOARD_TYPE  "STM32L1" 
        
           #elif defined(STM32L4) 
        
             #warning STM32L4 board selected 
        
             #define BOARD_TYPE  "STM32L4" 
        
           #elif defined(STM32H7) 
        
             #warning STM32H7 board selected 
        
             #define BOARD_TYPE  "STM32H7" 
        
           #elif defined(STM32G0) 
        
             #warning STM32G0 board selected 
        
             #define BOARD_TYPE  "STM32G0" 
        
           #elif defined(STM32G4) 
        
             #warning STM32G4 board selected 
        
             #define BOARD_TYPE  "STM32G4" 
        
           #elif defined(STM32WB) 
        
             #warning STM32WB board selected 
        
             #define BOARD_TYPE  "STM32WB" 
        
           #elif defined(STM32MP1) 
        
             #warning STM32MP1 board selected 
        
             #define BOARD_TYPE  "STM32MP1" 
        
           #else 
        
             #warning STM32 unknown board selected 
        
             #define BOARD_TYPE  "STM32 Unknown" 
        
           #endif 
        
           #ifndef BOARD_NAME 
        
             #define BOARD_NAME    BOARD_TYPE 
        
           #endif 
        
           #define SHIELD_TYPE     "LAN8742A built-in Ethernet" 
        
           #include <LwIP.h> 
        
           #include <STM32Ethernet.h> 
        
           #include <AsyncWebServer_STM32.h> 
        
           // Enter a MAC address and IP address for your controller below. 
        
           #define NUMBER_OF_MAC      20 
        
           byte mac[][NUMBER_OF_MAC] = 
        
           { 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x01 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x02 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x03 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x04 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x05 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x06 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x07 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x08 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x09 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0A }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0B }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0C }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0D }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0E }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0F }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x10 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x11 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x12 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x13 }, 
        
             { 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x14 }, 
        
           }; 
        
           // Select the IP address according to your local network 
        
           IPAddress ip(192, 168, 2, 232); 
        
           AsyncWebServer    server(80); 
        
           int reqCount = 0;                // number of requests received 
        
           const int led = 13; 
        
           void handleRoot(AsyncWebServerRequest *request) 
        
           { 
        
             digitalWrite(led, 1); 
        
           #define BUFFER_SIZE     400 
        
             char temp[BUFFER_SIZE]; 
        
             int sec = millis() / 1000; 
        
             int min = sec / 60; 
        
             int hr = min / 60; 
        
             int day = hr / 24; 
        
             snprintf(temp, BUFFER_SIZE - 1, 
        
                      "<html>\ 
        
           <head>\ 
        
           <meta http-equiv='refresh' content='5'/>\ 
        
           <title>AsyncWebServer-%s</title>\ 
        
           <style>\ 
        
           body { background-color: #cccccc; font-family: Arial, Helvetica, Sans-Serif; Color: #000088; }\ 
        
           </style>\ 
        
           </head>\ 
        
           <body>\ 
        
           <h2>AsyncWebServer_STM32!</h2>\ 
        
           <h3>running on %s</h3>\ 
        
           <p>Uptime: %d d %02d:%02d:%02d</p>\ 
        
           <img src=\"/test.svg\" />\ 
        
           </body>\ 
        
           </html>", BOARD_NAME, BOARD_NAME, day, hr % 24, min % 60, sec % 60); 
        
             request->send(200, "text/html", temp); 
        
             digitalWrite(led, 0); 
        
           } 
        
           void handleNotFound(AsyncWebServerRequest *request) 
        
           { 
        
             digitalWrite(led, 1); 
        
             String message = "File Not Found\n\n"; 
        
             message += "URI: "; 
        
             message += request->url(); 
        
             message += "\nMethod: "; 
        
             message += (request->method() == HTTP_GET) ? "GET" : "POST"; 
        
             message += "\nArguments: "; 
        
             message += request->args(); 
        
             message += "\n"; 
        
             for (uint8_t i = 0; i < request->args(); i++) 
        
             { 
        
               message += " " + request->argName(i) + ": " + request->arg(i) + "\n"; 
        
             } 
        
             request->send(404, "text/plain", message); 
        
             digitalWrite(led, 0); 
        
           } 
        
           void drawGraph(AsyncWebServerRequest *request) 
        
           { 
        
             String out; 
        
             out.reserve(3000); 
        
             char temp[70]; 
        
             out += "<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" width=\"310\" height=\"150\">\n"; 
        
             out += "<rect width=\"310\" height=\"150\" fill=\"rgb(250, 230, 210)\" stroke-width=\"2\" stroke=\"rgb(0, 0, 0)\" />\n"; 
        
             out += "<g stroke=\"blue\">\n"; 
        
             int y = rand() % 130; 
        
             for (int x = 10; x < 300; x += 10) 
        
             { 
        
               int y2 = rand() % 130; 
        
               sprintf(temp, "<line x1=\"%d\" y1=\"%d\" x2=\"%d\" y2=\"%d\" stroke-width=\"2\" />\n", x, 140 - y, x + 10, 140 - y2); 
        
               out += temp; 
        
               y = y2; 
        
             } 
        
             out += "</g>\n</svg>\n"; 
        
             request->send(200, "image/svg+xml", out); 
        
           } 
        
           void setup(void) 
        
           { 
        
             pinMode(led, OUTPUT); 
        
             digitalWrite(led, 0); 
        
             Serial.begin(115200); 
        
             while (!Serial); 
        
             delay(200); 
        
             Serial.print("\nStart Async_AdvancedWebServer_STM32 on "); Serial.print(BOARD_NAME); 
        
             Serial.print(" with "); Serial.println(SHIELD_TYPE); 
        
             Serial.println(ASYNC_WEBSERVER_STM32_VERSION); 
        
           #if (_ASYNCWEBSERVER_STM32_LOGLEVEL_ > 2) 
        
             Serial.print("STM32 Core version v"); Serial.print(STM32_CORE_VERSION_MAJOR); 
        
             Serial.print("."); Serial.print(STM32_CORE_VERSION_MINOR);  
        
             Serial.print("."); Serial.println(STM32_CORE_VERSION_PATCH); 
        
           #endif 
        
             // start the ethernet connection and the server 
        
             // Use random mac 
        
             uint16_t index = millis() % NUMBER_OF_MAC; 
        
             // Use Static IP 
        
             //Ethernet.begin(mac[index], ip); 
        
             // Use DHCP dynamic IP and random mac 
        
             Ethernet.begin(mac[index]); 
        
             server.on("/", HTTP_GET, [](AsyncWebServerRequest * request) 
        
             { 
        
               handleRoot(request); 
        
             }); 
        
             server.on("/test.svg", HTTP_GET, [](AsyncWebServerRequest * request) 
        
             { 
        
               drawGraph(request); 
        
             }); 
        
             server.on("/inline", [](AsyncWebServerRequest * request) 
        
             { 
        
               request->send(200, "text/plain", "This works as well"); 
        
             }); 
        
             server.onNotFound(handleNotFound); 
        
             server.begin(); 
        
             Serial.print(F("HTTP EthernetWebServer is @ IP : ")); 
        
             Serial.println(Ethernet.localIP()); 
        
           } 
        
           void loop(void) 
        
           { 
        
           }

You can access the Async Advanced WebServer @ the server IP

Debug Termimal Output Samples

1. AsyncMultiWebServer_STM32 on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library

Following are debug terminal output and screen shots when running example AsyncMultiWebServer_STM32 on STM32F7 Nucleo-144 NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library to demonstrate the operation of 3 independent AsyncWebServers on 3 different ports and how to handle the complicated AsyncMultiWebServers.

Starting AsyncMultiWebServer_STM32 on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0

Connected to network. IP = 192.168.2.141
Initialize multiServer OK, serverIndex = 0, port = 8080
HTTP server started at ports 8080
Initialize multiServer OK, serverIndex = 1, port = 8081
HTTP server started at ports 8081
Initialize multiServer OK, serverIndex = 2, port = 8082
HTTP server started at ports 8082

You can access the Async Advanced WebServers @ the server IP and corresponding ports (8080, 8081 and 8082)

2. WebClient on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library

Following is debug terminal output when running example WebClient on STM32F7 Nucleo-144 NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library.

Starting WebClient on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0
You're connected to the network, IP = 192.168.2.71

Starting connection to server...
Connected to server
HTTP/1.1 200 OK
Server: nginx/1.4.2
Date: Mon, 28 Dec 2020 22:30:39 GMT
Content-Type: text/plain
Content-Length: 2263
Last-Modified: Wed, 02 Oct 2013 13:46:47 GMT
Connection: close
Vary: Accept-Encoding
ETag: "524c23c7-8d7"
Accept-Ranges: bytes


           `:;;;,`                      .:;;:.           
        .;;;;;;;;;;;`                :;;;;;;;;;;:     TM 
      `;;;;;;;;;;;;;;;`            :;;;;;;;;;;;;;;;      
     :;;;;;;;;;;;;;;;;;;         `;;;;;;;;;;;;;;;;;;     
    ;;;;;;;;;;;;;;;;;;;;;       .;;;;;;;;;;;;;;;;;;;;    
   ;;;;;;;;:`   `;;;;;;;;;     ,;;;;;;;;.`   .;;;;;;;;   
  .;;;;;;,         :;;;;;;;   .;;;;;;;          ;;;;;;;  
  ;;;;;;             ;;;;;;;  ;;;;;;,            ;;;;;;. 
 ,;;;;;               ;;;;;;.;;;;;;`              ;;;;;; 
 ;;;;;.                ;;;;;;;;;;;`      ```       ;;;;;`
 ;;;;;                  ;;;;;;;;;,       ;;;       .;;;;;
`;;;;:                  `;;;;;;;;        ;;;        ;;;;;
,;;;;`    `,,,,,,,,      ;;;;;;;      .,,;;;,,,     ;;;;;
:;;;;`    .;;;;;;;;       ;;;;;,      :;;;;;;;;     ;;;;;
:;;;;`    .;;;;;;;;      `;;;;;;      :;;;;;;;;     ;;;;;
.;;;;.                   ;;;;;;;.        ;;;        ;;;;;
 ;;;;;                  ;;;;;;;;;        ;;;        ;;;;;
 ;;;;;                 .;;;;;;;;;;       ;;;       ;;;;;,
 ;;;;;;               `;;;;;;;;;;;;                ;;;;; 
 `;;;;;,             .;;;;;; ;;;;;;;              ;;;;;; 
  ;;;;;;:           :;;;;;;.  ;;;;;;;            ;;;;;;  
   ;;;;;;;`       .;;;;;;;,    ;;;;;;;;        ;;;;;;;:  
    ;;;;;;;;;:,:;;;;;;;;;:      ;;;;;;;;;;:,;;;;;;;;;;   
    `;;;;;;;;;;;;;;;;;;;.        ;;;;;;;;;;;;;;;;;;;;    
      ;;;;;;;;;;;;;;;;;           :;;;;;;;;;;;;;;;;:     
       ,;;;;;;;;;;;;;,              ;;;;;;;;;;;;;;       
         .;;;;;;;;;`                  ,;;;;;;;;:         
                                                         
                                                         
                                                         
                                                         
    ;;;   ;;;;;`  ;;;;:  .;;  ;; ,;;;;;, ;;. `;,  ;;;;   
    ;;;   ;;:;;;  ;;;;;; .;;  ;; ,;;;;;: ;;; `;, ;;;:;;  
   ,;:;   ;;  ;;  ;;  ;; .;;  ;;   ,;,   ;;;,`;, ;;  ;;  
   ;; ;:  ;;  ;;  ;;  ;; .;;  ;;   ,;,   ;;;;`;, ;;  ;;. 
   ;: ;;  ;;;;;:  ;;  ;; .;;  ;;   ,;,   ;;`;;;, ;;  ;;` 
  ,;;;;;  ;;`;;   ;;  ;; .;;  ;;   ,;,   ;; ;;;, ;;  ;;  
  ;;  ,;, ;; .;;  ;;;;;:  ;;;;;: ,;;;;;: ;;  ;;, ;;;;;;  
  ;;   ;; ;;  ;;` ;;;;.   `;;;:  ,;;;;;, ;;  ;;,  ;;;;   

Disconnecting from server...

3. MQTTClient_Auth on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library

Following is debug terminal output when running example MQTTClient_Auth on STM32F7 Nucleo-144 NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library.

Starting MQTTClient_Auth on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0

Connected to network. IP = 192.168.2.71
Attempting MQTT connection to broker.emqx.io...connected
Message Send : MQTT_Pub => Hello from MQTTClient_Auth on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Auth on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth on NUCLEO_F767ZI with LAN8742A built-in Ethernet

4. MQTTClient_Basic on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library

Following is debug terminal output when running example MQTTClient_Basic on STM32F7 Nucleo-144 NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library.

Starting MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0

Connected to network. IP = 192.168.2.71
Attempting MQTT connection to broker.shiftr.io...connected
Message Send : MQTT_Pub => Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Basic on NUCLEO_F767ZI with LAN8742A built-in Ethernet

5. MQTT_ThingStream on NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library

Following is debug terminal output when running example MQTT_ThingStream on STM32F7 Nucleo-144 NUCLEO_F767ZI using Built-in LAN8742A Ethernet and STM32Ethernet Library.

Starting MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0

Connected to network. IP = 192.168.2.71
***************************************
STM32_Pub
***************************************
Attempting MQTT connection to broker.emqx.io
...connected
Published connection message successfully!
Subscribed to: STM32_Sub
MQTT Message Send : STM32_Pub => Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message receive [STM32_Pub] Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message Send : STM32_Pub => Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message receive [STM32_Pub] Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message Send : STM32_Pub => Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message receive [STM32_Pub] Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message Send : STM32_Pub => Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message receive [STM32_Pub] Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message Send : STM32_Pub => Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet
MQTT Message receive [STM32_Pub] Hello from MQTT_ThingStream on NUCLEO_F767ZI with LAN8742A built-in Ethernet

6. MQTTClient_Auth_LAN8720 on BLACK_F407VE using LAN8720 Ethernet and STM32Ethernet Library

Following is debug terminal output when running example MQTTClient_Auth_LAN8720 on STM32F4 BLACK_F407VE with LAN8720 Ethernet and STM32Ethernet Library.

Start MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
AsyncWebServer_STM32 v1.6.0

Connected to network. IP = 192.168.2.150
Attempting MQTT connection to broker.emqx.io...connected
Message Send : MQTT_Pub => Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message Send : MQTT_Pub => Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
Message arrived [MQTT_Pub] Hello from MQTTClient_Auth_LAN8720 on BLACK_F407VE with LAN8720 Ethernet

7. Async_AdvancedWebServer_LAN8720 on BLACK_F407VE using LAN8720 Ethernet and STM32Ethernet Library

Following is the screen shot when running example Async_AdvancedWebServer_LAN8720 on STM32F4 BLACK_F407VE with LAN8720 Ethernet and STM32Ethernet Library to demonstrate the operation of AsyncWebServer.

8. AsyncMultiWebServer_STM32_LAN8720 on BLACK_F407VE using LAN8720 Ethernet and STM32Ethernet Library

Following are debug terminal output and screen shots when running example AsyncMultiWebServer_STM32_LAN8720 on STM32F4 BLACK_F407VE with LAN8720 Ethernet and STM32Ethernet Library to demonstrate the operation of 3 independent AsyncWebServers on 3 different ports and how to handle the complicated AsyncMultiWebServers.

Start AsyncMultiWebServer_STM32_LAN8720 on BLACK_F407VE with LAN8720 Ethernet
AsyncWebServer_STM32 v1.6.0

Connected to network. IP = 192.168.2.150
Initialize multiServer OK, serverIndex = 0, port = 8080
HTTP server started at ports 8080
Initialize multiServer OK, serverIndex = 1, port = 8081
HTTP server started at ports 8081
Initialize multiServer OK, serverIndex = 2, port = 8082
HTTP server started at ports 8082

You can access the Async Advanced WebServers @ the server IP and corresponding ports (8080, 8081 and 8082)

9. Async_AdvancedWebServer_favicon on NUCLEO_F767ZI with LAN8742A built-in Ethernet

Following is the debug terminal when running example Async_AdvancedWebServer_favicon on NUCLEO_F767ZI, with LAN8742A built-in Ethernet, to demonstrate the operation of AsyncWebServer_STM32, to display favicon.ico, which many browsers support.

Start Async_AdvancedWebServer_favicon on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0
STM32 Core version v2.2.0
HTTP EthernetWebServer is @ IP : 192.168.2.69

You can see the favicon.ico at the upper left corner

On Firefox

10. Async_AdvancedWebServer_MemoryIssues_Send_CString on NUCLEO_F767ZI with LAN8742A built-in Ethernet

Following is the debug terminal and screen shot when running example Async_AdvancedWebServer_MemoryIssues_Send_CString on NUCLEO_F767ZI, with LAN8742A built-in Ethernet, to demonstrate the new and powerful HEAP-saving feature

Using CString ===> small heap (42,952 bytes) for ~31 KBytes data length

Start Async_AdvancedWebServer_MemoryIssues_Send_CString on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0

HEAP DATA - Start =>  Free RAM: 479908  Used heap: 260
STM32 Core version v2.2.0
HTTP EthernetWebServer is @ IP : 192.168.2.72

HEAP DATA - Pre Create Arduino String  Free RAM: 439116  Used heap: 41052
.
HEAP DATA - Pre Send  Free RAM: 437380  Used heap: 42788

HEAP DATA - Post Send  Free RAM: 437216  Used heap: 42952
......
Out String Length=31248
... ....
Out String Length=31194
...... .
Out String Length=31223
.......
Out String Length=31244
.. .....

While using Arduino String, the HEAP usage is very large, even with smaller data. Unfortunately, we currently can't use Arduino String larger than 5,5 KBytes now.

Async_AdvancedWebServer_MemoryIssues_SendArduinoString ===> very large heap (48,716 bytes) for 5,592 bytes data

Start Async_AdvancedWebServer_MemoryIssues_SendArduinoString on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0

HEAP DATA - Start =>  Free RAM: 479908  Used heap: 260
STM32 Core version v2.2.0
HTTP EthernetWebServer is @ IP : 192.168.2.72

HEAP DATA - Pre Create Arduino String  Free RAM: 479124  Used heap: 1044
.
HEAP DATA - Pre Send  Free RAM: 437172  Used heap: 42996

HEAP DATA - Post Send  Free RAM: 431452  Used heap: 48716
......
Out String Length=5580
... ....
Out String Length=5583
...... .
Out String Length=5584
......
Out String Length=5585
... ....
Out String Length=5592
...

You can access the Async Advanced WebServers at the displayed server IP, e.g. 192.168.2.72

11. Async_AdvancedWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet

Following is debug terminal output when running example Async_AdvancedWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet, to demo how to use beginChunkedResponse() to send large html in chunks

Start Async_AdvancedWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.1
STM32 Core version v2.3.0
AsyncWebServer is @ IP : 192.168.2.124
.[AWS] Total length to send in chunks = 31262
[AWS] Bytes sent in chunk = 5716
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 2218
[AWS] Bytes sent in chunk = 0
[AWS] Total length to send in chunks = 31277
[AWS] Bytes sent in chunk = 5716
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 2233
[AWS] Bytes sent in chunk = 0
[AWS] Total length to send in chunks = 31233
[AWS] Bytes sent in chunk = 5716
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 2189
[AWS] Bytes sent in chunk = 0

You can access the Async_AdvancedWebServer_SendChunked at the displayed server IP, e.g. 192.168.2.123

12. AsyncWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet

Following is debug terminal output when running example AsyncWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet, to demo how to use beginChunkedResponse() to send large html in chunks

Start AsyncWebServer_SendChunked on NUCLEO_F767ZI with LAN8742A built-in Ethernet
AsyncWebServer_STM32 v1.6.0
STM32 Core version v2.3.0
AsyncWebServer is @ IP : 192.168.2.124
.[AWS] Total length to send in chunks = 41798
[AWS] Bytes sent in chunk = 5720
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 1086
[AWS] Bytes sent in chunk = 0
.[AWS] Total length to send in chunks = 41798
[AWS] Bytes sent in chunk = 5720
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 5832
[AWS] Bytes sent in chunk = 1086
[AWS] Bytes sent in chunk = 0

Debug

Debug is enabled by default on Serial. Debug Level from 0 to 4. To disable, change the ETHERNET_WEBSERVER_LOGLEVEL to 0

// Use this to output debug msgs to Serial
#define ASYNCWEBSERVER_STM32_DEBUG_PORT       Serial
// Use this to disable all output debug msgs
// Debug Level from 0 to 4
#define _ASYNCWEBSERVER_STM32_LOGLEVEL_       0

Troubleshooting

If you get compilation errors, more often than not, you may need to install a newer version of Arduino IDE, the Arduino STM32 core or depending libraries.

Sometimes, the library will only work if you update the STM32 core to the latest version because I'm always using the latest cores /libraries.

Issues

Submit issues to: AsyncWebServer_STM32 issues

TO DO

Fix bug. Add enhancement
Add support to more Ethernet / WiFi shield
Add support to more STM32 boards.
Add support to File using STM32-SD or STM32-FS

DONE

Initial port to STM32 using builtin LAN8742A Etnernet. Tested on STM32F7 Nucleo-144 F767ZI.
Add more examples.
Add debugging features.
Add AsyncUDP_STM32 to support Async UDP on STM32
Add Authentication support (MD5, SHA1).
Add support to Ethernet LAN8720 using STM32Ethernet library, for boards such as Nucleo-144 (F429ZI, NUCLEO_F746NG, NUCLEO_F746ZG, NUCLEO_F756ZG), Discovery (DISCO_F746NG) and STM32F4 boards (BLACK_F407VE, BLACK_F407VG, BLACK_F407ZE, BLACK_F407ZG, BLACK_F407VE_Mini, DIYMORE_F407VGT, FK407M1). Tested on STM32F4 BLACK_F407VE.
Add Table-of-Contents and Version String
Fix issue with slow browsers or network
Add functions and example Async_AdvancedWebServer_favicon to support favicon.ico
Support using CString to save heap to send very large data. Check request->send(200, textPlainStr, jsonChartDataCharStr); - Without using String Class - to save heap #8
Add examples Async_AdvancedWebServer_SendChunked and AsyncWebServer_SendChunked to demo how to use beginChunkedResponse() to send large html in chunks
Use allman astyle and add utils

Contributions and Thanks

Based on and modified from Hristo Gochkov's ESPAsyncWebServer. Many thanks to Hristo Gochkov for great ESPAsyncWebServer Library
Relied on Frederic Pillon's STM32duino LwIP Library.
Relied on PhilBowles' STM32 AsyncTCP Library.
Thanks to good work of Miguel Wisintainer for working with, developing, debugging and testing.
Thanks to Jean-Claude and chris007de to help locate the dependency issue, discuss solution leading to release v1.2.6. Check Compilation broken due to error in STM32AsyncTCP dependency and how to run one of the examples?.
Thanks to tothtechnika to create the PR Fix base64 encoding of websocket client key and progmem support for webserver #7 leading to new release v1.4.0
Thanks to salasidis aka rs77can to discuss and make the following marvellous PRs in Portenta_H7_AsyncWebServer library

request->send(200, textPlainStr, jsonChartDataCharStr); - Without using String Class - to save heap #8
All memmove() removed - string no longer destroyed #11, leading to v1.6.0 to support using CString to save heap to send very large data

_{⭐️⭐️ Hristo Gochkov}	_{⭐️ Frederic Pillon}	_{⭐️ Phil Bowles}	_tcpipchip	_Jean-Claude	_chris007de
_tothtechnika	_{⭐️ salasidis}

Contributing

If you want to contribute to this project:

Report bugs and errors
Ask for enhancements
Create issues and pull requests
Tell other people about this library

License

The library is licensed under GPLv3

	#if !( defined(STM32F0) \|\| defined(STM32F1) \|\| defined(STM32F2) \|\| defined(STM32F3) \|\|defined(STM32F4) \|\| defined(STM32F7) \|\| \
	defined(STM32L0) \|\| defined(STM32L1) \|\| defined(STM32L4) \|\| defined(STM32H7) \|\|defined(STM32G0) \|\| defined(STM32G4) \|\| \
	defined(STM32WB) \|\| defined(STM32MP1) )
	#error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting.
	#endif

	#define _ASYNCWEBSERVER_STM32_LOGLEVEL_ 4

	#if defined(STM32F0)
	#warning STM32F0 board selected
	#define BOARD_TYPE "STM32F0"
	#elif defined(STM32F1)
	#warning STM32F1 board selected
	#define BOARD_TYPE "STM32F1"
	#elif defined(STM32F2)
	#warning STM32F2 board selected
	#define BOARD_TYPE "STM32F2"
	#elif defined(STM32F3)
	#warning STM32F3 board selected
	#define BOARD_TYPE "STM32F3"
	#elif defined(STM32F4)
	#warning STM32F4 board selected
	#define BOARD_TYPE "STM32F4"
	#elif defined(STM32F7)
	#warning STM32F7 board selected
	#define BOARD_TYPE "STM32F7"
	#elif defined(STM32L0)
	#warning STM32L0 board selected
	#define BOARD_TYPE "STM32L0"
	#elif defined(STM32L1)
	#warning STM32L1 board selected
	#define BOARD_TYPE "STM32L1"
	#elif defined(STM32L4)
	#warning STM32L4 board selected
	#define BOARD_TYPE "STM32L4"
	#elif defined(STM32H7)
	#warning STM32H7 board selected
	#define BOARD_TYPE "STM32H7"
	#elif defined(STM32G0)
	#warning STM32G0 board selected
	#define BOARD_TYPE "STM32G0"
	#elif defined(STM32G4)
	#warning STM32G4 board selected
	#define BOARD_TYPE "STM32G4"
	#elif defined(STM32WB)
	#warning STM32WB board selected
	#define BOARD_TYPE "STM32WB"
	#elif defined(STM32MP1)
	#warning STM32MP1 board selected
	#define BOARD_TYPE "STM32MP1"
	#else
	#warning STM32 unknown board selected
	#define BOARD_TYPE "STM32 Unknown"
	#endif

	#ifndef BOARD_NAME
	#define BOARD_NAME BOARD_TYPE
	#endif

	#define SHIELD_TYPE "LAN8742A built-in Ethernet"

	#include <LwIP.h>
	#include <STM32Ethernet.h>
	#include <AsyncWebServer_STM32.h>

	// Enter a MAC address and IP address for your controller below.
	#define NUMBER_OF_MAC 20

	byte mac[][NUMBER_OF_MAC] =
	{
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x01 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x02 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x03 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x04 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x05 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x06 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x07 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x08 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x09 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0A },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0B },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0C },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0D },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0E },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x0F },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x10 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x11 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x12 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x13 },
	{ 0xDE, 0xAD, 0xBE, 0xEF, 0x32, 0x14 },
	};
	// Select the IP address according to your local network
	IPAddress ip(192, 168, 2, 232);

	AsyncWebServer server(80);

	int reqCount = 0; // number of requests received

	const int led = 13;

	void handleRoot(AsyncWebServerRequest *request)
	{
	digitalWrite(led, 1);

	#define BUFFER_SIZE 400

	char temp[BUFFER_SIZE];
	int sec = millis() / 1000;
	int min = sec / 60;
	int hr = min / 60;
	int day = hr / 24;

	snprintf(temp, BUFFER_SIZE - 1,
	"<html>\
	<head>\
	<meta http-equiv='refresh' content='5'/>\
	<title>AsyncWebServer-%s</title>\
	<style>\
	body { background-color: #cccccc; font-family: Arial, Helvetica, Sans-Serif; Color: #000088; }\
	</style>\
	</head>\
	<body>\
	<h2>AsyncWebServer_STM32!</h2>\
	<h3>running on %s</h3>\
	<p>Uptime: %d d %02d:%02d:%02d</p>\
	<img src=\"/test.svg\" />\
	</body>\
	</html>", BOARD_NAME, BOARD_NAME, day, hr % 24, min % 60, sec % 60);

	request->send(200, "text/html", temp);

	digitalWrite(led, 0);
	}

	void handleNotFound(AsyncWebServerRequest *request)
	{
	digitalWrite(led, 1);
	String message = "File Not Found\n\n";

	message += "URI: ";
	message += request->url();
	message += "\nMethod: ";
	message += (request->method() == HTTP_GET) ? "GET" : "POST";
	message += "\nArguments: ";
	message += request->args();
	message += "\n";

	for (uint8_t i = 0; i < request->args(); i++)
	{
	message += " " + request->argName(i) + ": " + request->arg(i) + "\n";
	}

	request->send(404, "text/plain", message);
	digitalWrite(led, 0);
	}

	void drawGraph(AsyncWebServerRequest *request)
	{
	String out;

	out.reserve(3000);
	char temp[70];

	out += "<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" width=\"310\" height=\"150\">\n";
	out += "<rect width=\"310\" height=\"150\" fill=\"rgb(250, 230, 210)\" stroke-width=\"2\" stroke=\"rgb(0, 0, 0)\" />\n";
	out += "<g stroke=\"blue\">\n";
	int y = rand() % 130;

	for (int x = 10; x < 300; x += 10)
	{
	int y2 = rand() % 130;
	sprintf(temp, "<line x1=\"%d\" y1=\"%d\" x2=\"%d\" y2=\"%d\" stroke-width=\"2\" />\n", x, 140 - y, x + 10, 140 - y2);
	out += temp;
	y = y2;
	}
	out += "</g>\n</svg>\n";

	request->send(200, "image/svg+xml", out);
	}


	void setup(void)
	{
	pinMode(led, OUTPUT);
	digitalWrite(led, 0);

	Serial.begin(115200);
	while (!Serial);

	delay(200);

	Serial.print("\nStart Async_AdvancedWebServer_STM32 on "); Serial.print(BOARD_NAME);
	Serial.print(" with "); Serial.println(SHIELD_TYPE);
	Serial.println(ASYNC_WEBSERVER_STM32_VERSION);

	#if (_ASYNCWEBSERVER_STM32_LOGLEVEL_ > 2)
	Serial.print("STM32 Core version v"); Serial.print(STM32_CORE_VERSION_MAJOR);
	Serial.print("."); Serial.print(STM32_CORE_VERSION_MINOR);
	Serial.print("."); Serial.println(STM32_CORE_VERSION_PATCH);
	#endif

	// start the ethernet connection and the server
	// Use random mac
	uint16_t index = millis() % NUMBER_OF_MAC;

	// Use Static IP
	//Ethernet.begin(mac[index], ip);
	// Use DHCP dynamic IP and random mac
	Ethernet.begin(mac[index]);

	server.on("/", HTTP_GET, [](AsyncWebServerRequest * request)
	{
	handleRoot(request);
	});

	server.on("/test.svg", HTTP_GET, [](AsyncWebServerRequest * request)
	{
	drawGraph(request);
	});

	server.on("/inline", [](AsyncWebServerRequest * request)
	{
	request->send(200, "text/plain", "This works as well");
	});

	server.onNotFound(handleNotFound);

	server.begin();

	Serial.print(F("HTTP EthernetWebServer is @ IP : "));
	Serial.println(Ethernet.localIP());
	}

	void loop(void)
	{
	}

Files

README.md

Latest commit

History

README.md

File metadata and controls

AsyncWebServer_STM32

Table of contents

Important Change from v1.5.0

Important Note from v1.6.0

Why do we need this AsyncWebServer_STM32 library

Features

Why Async is better

Currently supported Boards

Prerequisites

Installation

Use Arduino Library Manager

Manual Install

VS Code & PlatformIO:

Packages' Patches

1. For STM32 boards to use LAN8720

2. For STM32 boards to use Serial1

Important things to remember

Principles of operation

The Async Web server

Request Life Cycle

Rewrites and how do they work

Handlers and how do they work

Responses and how do they work

Template processing

Request Variables

Common Variables

Headers

GET, POST and FILE parameters

JSON body handling with ArduinoJson

Responses

Redirect to another URL

Basic response with HTTP Code

Basic response with HTTP Code and extra headers

Basic response with string content

Basic response with string content and extra headers

Respond with content coming from a Stream

Respond with content coming from a Stream and extra headers

Respond with content coming from a Stream containing templates

Respond with content coming from a Stream containing templates and extra headers

Respond with content using a callback

Respond with content using a callback and extra headers

Respond with content using a callback containing templates

Respond with content using a callback containing templates and extra headers

Chunked Response

Chunked Response containing templates

Print to response

ArduinoJson Basic Response

ArduinoJson Advanced Response

Param Rewrite With Matching

Using filters

Bad Responses

Respond with content using a callback without content length to HTTP/1.0 clients

Async WebSocket Plugin

Async WebSocket Event

Methods for sending data to a socket client

Direct access to web socket message buffer

Limiting the number of web socket clients

Async Event Source Plugin

Setup Event Source on the server

Setup Event Source in the browser

Remove handlers and rewrites

Setting up the server

Setup global and class functions as request handlers

Methods for controlling websocket connections

Adding Default Headers

Path variable

HOWTO use STM32F4 with LAN8720

1. Wiring

2. HOWTO program using STLink V-2 or V-3

3. HOWTO use Serial Port for Debugging

Examples

1. For LAN8742A

2. For LAN8720

Example Async_AdvancedWebServer