There is a good choice of different Http Server implementations for Arduino. Somehow however I was always fighting with some restrictions: E.g the server was crashing because it was running out of memory.
So I decided to to investigate if it is possible to achieve the following goals:
- Serving of a potentially unbounded amount of data
- concurrent handling of multiple requests.
- Support for Extensions to add additional functionality
In my alternative design I try to split the processing up into many small pieces: So instead of sending a single big reply we can use the chunked http transfer encoding to feed many clients with small replys.
This should resolve also the memory restrictions for good because we do not have any upper totoal limit for the reply any more!
The basic HttpServer class just provides the functionality to
- receive / interpret requests
- define rewrites
- register reply handlers (callbacks)
- register extensions
- provide replys
- forward to URL
- tunnel to URL
I also added a small http client implementation by re-using the same functionality which was needed for the Server.
A simple demo that shows how to use the basic server functionality w/o extensions.
#include "HttpServer.h"
// setup server with initial dump address
WiFiServer wifi;
HttpServer server(wifi);
Url indexUrl("/index.html");
void setup() {
Serial.begin(115200);
HttpLogger.begin(Serial,Info);
const char*htmlHallo =
"<!DOCTYPE html>"
"<html>"
"<body style='background-color:black; color:white'>"
"<h1>Arduino Http Server</h1>"
"<p>Hallo world...</p>"
"</body>"
"</html>";
auto countLambda = [](HttpServer *server, const char*requestPath, HttpRequestHandlerLine *hl) {
char buffer[2048];
Str str(buffer, 2048);
str += "<!DOCTYPE html>";
str += "<html>";
str += "<body style='background-color:black; color:white'>";
str += "<h1>Counting Callback Example </h1> ";
for (int j=0;j<100;j++){
str+= "test ";
str += j;
str += "<br>";
}
str += "</body></html>";
server->reply("text/html", str.c_str(), 200, SUCCESS);
};
server.rewrite("/","/hallo.html");
server.rewrite("/index.html","/hallo.html");
server.on("/hallo.html",T_GET,"text/html",htmlHallo);
server.on("/count", T_GET, countLambda);
server.on("/moved", T_GET, indexUrl);
server.begin(80, "SSID", "password");
}
void loop(){
server.doLoop();
}
The application has a built in logger. You can set the log level (Debug, Info, Warning, Error) with
HttpLogger.begin(Serial, tinyhttp::Info);
In order to be able to support an unlimited number of more complex scenarios, I have designed the concept of flexible "Extensions" and to proof the usefulness I have implemented the support for the following extensions:
- Publishing of Output from an Arduino Stream
- Music Streaming to multiple clients
- Serving web pages from SD
You can "write log messages" to an Arduino stream and look at the result from multiple browser windows:
#include "HttpServer.h"
// setup server
WiFiServer wifi;
HttpServer server(wifi);
ExtensionLoggingStream stream("/log" );
Ticker ticker;
void setup() {
Serial.begin(115200);
HttpLogger.begin(Serial,Info);
ticker.schedule(1000,&printMsg);
server.addExtension(stream);
server.begin(80,"SSID", "password" );
}
void printMsg(void*){
static int count;
char str[20];
sprintf(str,"counter: %d",count++);
stream.println(str); // log to server
Serial.println(str); // log to Serial
}
void loop(){
server.doLoop();
ticker.doLoop();
}
Further extension examples can be found in the examples directory!
- Here is the Class Documentation.
- Please also check out the Information in the Wiki and my TinyHttp Blogs
You can download the library as zip and call include Library -> zip library. Or you can git clone this project into the Arduino libraries folder e.g. with
cd ~/Documents/Arduino/libraries
git clone pschatzmann/TinyHttp.git
I recommend to use git because you can easily update to the latest version just by executing the git pull command in the project folder.