How to build HTTP Response with ESP8266 and Arduino

Question

I want to toggle some LEDs with my Android device. These LEDs are connected to the digital Pins of my Arduino which is also connected to a ESP8266. Now, my ESP8266 is defined as an AccessPoint and my Tablet can send HTTP requests (e.g. http://192.168.4.1:80/?pin=11). I found the code here http://allaboutee.com/2015/01/20/esp8266-android-application-for-arduino-pin-control/

It works fine but my question is which HTTP header fields should be used? In this code he used some (e.g. Content-Length) but there are so much more possible (Date, Server, Content-Language,...).

Are these fields optional or which of these have to be used to build the right response?

Here is the piece of code I do not understand:

void sendHTTPResponse(int connectionId, String content)

{

 String httpResponse;
 String httpHeader;

 httpHeader = "HTTP/1.1 200 OK\r\nContent-Type: text/html; charset=UTF-8\r\n"; 
 httpHeader += "Content-Length: ";
 httpHeader += content.length();
 httpHeader += "\r\n";
 httpHeader +="Connection: close\r\n\r\n";
 httpResponse = httpHeader + content + " ";
 sendCIPData(connectionId,httpResponse);

}

The list of possible header fields can be found here: en.wikipedia.org/wiki/List_of_HTTP_header_fields — TeaAge
– TeaAge, Commented Jul 5, 2016 at 6:48

Marcel Stör · Accepted Answer · 2016-07-05 09:57:30Z

1

It largely depends on the client (i.e. consumer) which fields are required and which are mandatory.

The only one that is always required is "HTTP/1.1 200 OK". Of course you need to replace that status code if you're not sending an OK message.

edited Jul 5, 2016 at 9:57

answered Jul 5, 2016 at 7:11

Marcel Stör

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2 Comments

TeaAge Over a year ago

Thanks for the fast reply @MarcelStör ! So if I want to get a feedback on my Android device I need to have this "HTTP/1.1 200 OK" but the other fields are optional right ? And what does this HTTP/1.1 200 stand for ?

Marcel Stör Over a year ago

If your Android device expects HTTP then you need to declare the response as being an HTTP response. "HTTP/1.1" is the protocol and "200 OK" is the status. You also need to have the "\r\n" in place as shown in the example you posted. I suggest you familiarize yourself with code.tutsplus.com/tutorials/http-headers-for-dummies--net-8039.

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