TinyWoT Protocol Binding - Simple HTTP

This is a simple protocol binding implementation for TinyWoT to transform HTTP requests into TinyWoT requests and TinyWoT responses into HTTP responses. Features include:

Installation

PlatformIO: pio lib install tinywot-http-simple

Dependencies

TinyWoT (build-time)
A standard C library (libc)

Use

Prepare a configuration object (TinyWoTHTTPSimpleConfig). This include:

a read line handler (readln)
a write handler (write)
a buffer "scratchpad" (linebuf) and its size (linebuf_size)
a buffer storing the path (pathbuf) and its size (pathbuf_size)
an optional context pointer (ctx) for the use of read / write handlers; for example, a socket

Upon a network request, invoke tinywot_http_simple_recv with the configuration object and a pointer to TinyWoTRequest. The function will fill the TinyWoTRequest while consuming the HTTP request.
After tinywot_process, invoke tinywot_http_simple_send with the configuration object and a pointer to the TinyWoTResponse returned. The function will emit HTTP response texts according to the TinyWoTResponse.

if (!tinywot_http_simple_recv(&cfg, &req)) {
  // error handling
}

resp = tinywot_process(&thing, &req);

if (!tinywot_http_simple_send(&cfg, &resp)) {
  // error handling
}

A sample Thing implemented using this library based on Arduino with Ethernet connectivity can be found in example/arduino-led.

Configuration

A few macros can be defined in the build system to tweak this library:

TINYWOT_HTTP_SIMPLE_USE_PROGMEM: use AVR program space (flash memory) to store the HTTP strings. Toggling this helps saving around 40% of RAM that is purely used to store static HTTP strings.
TINYWOT_HTTP_SIMPLE_USE_REASON_PHRASE: append optional HTTP reason phrases in the response line of responses.

For example, in PlatformIO, insert build_flags in [env] blocks:

build_flags =
  -DTINYWOT_HTTP_SIMPLE_USE_PROGMEM
  -DTINYWOT_HTTP_SIMPLE_USE_REASON_PHRASE

For TinyWoT configuration options, see its documentation.

Limitations

As a "simple" implementation, it just works and doesn't cover too many use cases.

This library parses HTTP line-by-line, so the size of buffer (linebuf, as the name suggests) essentially limits the maximum possible length of a HTTP request. If a HTTP request has a line longer than the size of buffer, the receiving or the sending process will fail. It's recommended to set linebuf_size to a value larger than 64 (bytes).
- The same for pathbuf storing the incoming path.

License

This project is REUSE 3.0 compliant: every file is carried with its own copyright and licensing information in the comment headers or the corresponding .license files. In general:

Source files are licensed under the MIT license.
Various data files are (un)licensed under the CC0 license.

See the LICENSES directory for copies of licenses used across this project. The LICENSE file also contains a MIT license for non-REUSE practices.

jyhi / tinywot-http-simple