#summary An HTTP-based API endpoint for Arduino-style devices
#labels Arduino,HTTP,API,Microcontroller,Library

The *Endpoint* library is a minimalist library to create an HTTP-based API endpoint on an Arduino device. This allows more complex systems (such as Python, Java, or web browsers) to connect to the device to issue a command or fetch data.

An Arduino application can use this library to receive commands and parameters over the network (represented as a set of bytes), perform an operation, and respond with pass/fail to the caller with optional return values.

== Design ==

Interacting with the Arduino is performed through a simple HTTP GET operation. URLs are constructed as: `/X/(hh)*` where X is a single alphanumeric character specifying the endpoint, and hh is a 2-character hexadecimal value specifying a set of parameters for the endpoint.

Responses are delivered as one of three options:

  * 204 (No Content) -- the operation succeeded, with no further response data
  * 200 (OK) -- the body contains N bytes of response data, as a series of bytes represented in hex
  * 400 (Bad Request) -- the query was not formed properly

The HTTP connection remains open for successful operations, and is closed/shutdown on a 400 response. The HTTP protocol is observed, so this library should work with any client application/library, but only the barest minimum of the protocol is actually used.

== Code ==

Located at: https://gstein.googlecode.com/svn/trunk/arduino/endpoint/

== Size ==

The Endpoint library is a bit larger than 1000 bytes, when compiled for my ATmega328 processor. Another 10k bytes are pulled in for the Ethernet and SPI libraries.

== TODO ==

  * more documentation
  * package it as a real library
  * submit to Arduino community "contrib" section
  * expanded tests/example