Arduino MiniWebServer
A small web server for Arduino.
Check out this video demonstrating what you can do with it:
http://www.youtube.com/watch?v=qZXKk6nCYuM
You can read up on MiniWebServer's history here:
http://www.webweavertech.com/ovidiu/weblog/archives/000484.html
http://www.webweavertech.com/ovidiu/weblog/archives/000477.html
The library is licensed under the terms of LGPL 2.1. Which means you're free to use it in your projects (including commercial ones) as long as you're sending back the changes you make to the library.
MiniWebServer depends on the external library Flash version 4.0, which is found here:
http://arduiniana.org/libraries/flash/
Make sure you dowload the Flash library and install it in your
Arduino's libraries directory, as described in this document:
http://arduino.cc/en/Guide/Libraries
To make use of the MiniWebServer library, you need to include the following your sketch:
#include <Ethernet.h>
#include <Flash.h>
#include <MiniWebServer.h>
TWS is implemented by the MiniWebServer class. The constructor method takes two arguments. The first one is a list of handlers, functions to be invoked when a particular URL is requested by an HTTP client. The second one is a list of HTTP header names that are needed by the implementation of your handlers. More on these later.
An HTTP handler is a simple function that takes as argument a reference to the MiniWebServer object. When you create the MiniWebServer class, you need to pass in the handlers for the various URLs. Here is a simple example of a web server with a single handler.
static uint8_t mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
//pin connected to RSTn on WIZ550io
const byte WIZ_RST = 8;
boolean index_handler(MiniWebServer& web_server) {
web_server.send_error_code(200);
web_server << F("<html><body><h1>Hello World!</h1></body></html>\n");
return true;
}
MiniWebServer::PathHandler handlers[] = {
// Register the index_handler for GET requests on /
{"/", MiniWebServer::GET, &index_handler },
{NULL}, // The array has to be NULL terminated this way
};
// Create an instance of the web server. No HTTP headers are requested
// by the HTTP request handlers.
MiniWebServer web = MiniWebServer(handlers, NULL);
void setup() {
Serial.begin(115200);
// restarting wiznet
pinMode(WIZ_RST, OUTPUT);
//initialise RSTn
digitalWrite(WIZ_RST, LOW);
delay(1);
digitalWrite(WIZ_RST, HIGH);
delay(500);
EthernetDHCP.begin(mac);
web.begin();
}
void loop() {
EthernetDHCP.maintain();
web.process();
}
In the loop() function we need the call to the process() to make sure HTTP requests are serviced. If there is no new request, the method returns immediately. Otherwise the process() method blocks until the request is handled.
For a complete working example look in MiniWebServer/example/SimpleWebServer.
Sometimes it's useful to have an HTTP client start a request. For example, I need to be able to enter an IR learning process. This means that I cannot afford MiniWebServer's process() to block while serving my /learn request that initiated the IR learning process. Instead I want the handler of the /learn request to set a variable in the code that indicates that IR learning is active, and then return immediately.
If you noticed the HTTP handlers return a boolean. If the returned value is true, as it was the case in our examples above, the connection to the HTTP client is closed immediately. If the returned value is false the connection is left open. Your handler should save the Client object handling the HTTP connection with the original request. Your code becomes responsible with closing it when it's no longer needed.
To obtain the Client object, use the get_client() method while in the HTTP handler. You can write asynchronously to the client, to update it with the state of the web server.
In my remotely controlled projection screen application, I have another handler on /cancel that closes the /learn client forcibly. Otherwise the /learn's Client connection is closed at the end of the IR learning procedure. Since the Ethernet shield only allows for 4 maximum HTTP clients open at the same time (because of 4 maximum client sockets), in my application I allow only one /learn handler to be active at any given time.