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TinyWeb Build Status

Simple and lightweight (thus - tiny) HTTP server for tiny devices like ESP8266 / ESP32 running micropython. Having simple HTTP server allows developers to create nice and modern UI for their IoT devices. By itself - tinyweb is just simple TCP server running on top of uasyncio - library for micropython, therefore tinyweb is single threaded server.

Features

  • Fully asynchronous when using with uasyncio library for MicroPython.
  • Flask / Flask-RESTful like API.
  • Tiny memory usage. So you can run it on devices like ESP8266 / ESP32 with 64K/96K of onboard RAM. BTW, there is a huge room for optimizations - so your contributions are warmly welcomed.
  • Support for static content serving from filesystem.
  • Great unittest coverage. So you can be confident about quality :)

Requirements

On MicroPython <1.13:

Quickstart

The easist way to try it - is using pre-compiled firmware for ESP8266 / ESP32. Instructions below are tested with NodeMCU devices. For any other devices instructions could be a bit different, so keep in mind. CAUTION: If you proceed with installation all data on your device will lost!

Installation - ESP8266

  • Download latest firmware_esp8266-version.bin from releases.
  • Install esp-tool if you haven't done already: pip install esptool
  • Erase flash: esptool.py --port <UART PORT> --baud 256000 erase_flash
  • Flash firmware: esptool.py --port <UART PORT> --baud 256000 write_flash -fm dio 0 firmware_esp8266-v1.3.2.bin

Installation - ESP32

  • Download latest firmware_esp32-version.bin from releases.
  • Install esp-tool if you haven't done already: pip install esptool
  • Erase flash: esptool.py --port <UART PORT> --baud 256000 erase_flash
  • Flash firmware: esptool.py --port <UART PORT> --baud 256000 write_flash -fm dio 0x1000 firmware_esp32-v1.3.2.bin

Hello world

Let's develop Hello World web app:

import tinyweb


# Create web server application
app = tinyweb.webserver()


# Index page
@app.route('/')
async def index(request, response):
    # Start HTTP response with content-type text/html
    await response.start_html()
    # Send actual HTML page
    await response.send('<html><body><h1>Hello, world! (<a href="/table">table</a>)</h1></html>\n')


# Another one, more complicated page
@app.route('/table')
async def table(request, response):
    # Start HTTP response with content-type text/html
    await response.start_html()
    await response.send('<html><body><h1>Simple table</h1>'
                        '<table border=1 width=400>'
                        '<tr><td>Name</td><td>Some Value</td></tr>')
    for i in range(10):
        await response.send('<tr><td>Name{}</td><td>Value{}</td></tr>'.format(i, i))
    await response.send('</table>'
                        '</html>')


def run():
    app.run(host='0.0.0.0', port=8081)

Simple? Let's try it! Flash your device with firmware, open REPL and type:

>>> import network

# Connect to WiFi
>>> sta_if = network.WLAN(network.STA_IF)
>>> sta_if.active(True)
>>> sta_if.connect('<ssid>', '<password>')

# Run Hello World! :)
>>> import examples.hello_world as hello
>>> hello.run()

That's it! :) Try it by open page http://<your ip>:8081

Like it? Check more examples then :)

Limitations

  • HTTP protocol support - due to memory constrains only HTTP/1.0 is supported (with exception for REST API - it uses HTTP/1.1 with Connection: close). Support of HTTP/1.1 may be added when esp8266 platform will be completely deprecated.

Reference

class webserver

Main tinyweb app class.

  • __init__(self, request_timeout=3, max_concurrency=None) - Create instance of webserver class.

    • request_timeout - Specifies timeout for client to send complete HTTP request (without HTTP body, if any), after that connection will be closed. Since uasyncio has very short queue (about 42 items) Avoid using values > 5 to prevent events queue overflow.
    • max_concurrency - How many connections can be processed concurrently. It is very important to limit it mostly because of memory constrain. Default value depends on platform, 3 for esp8266, 6 for esp32 and 10 for others.
    • backlog - Parameter to socket.listen() function. Defines size of pending to be accepted connections queue. Must be greater than max_concurrency.
    • debug - Whether send exception info (text + backtrace) to client together with HTTP 500 or not.
  • add_route(self, url, f, **kwargs) - Map url into function f. Additional keyword arguments are supported:

    • methods - List of allowed methods. Defaults to ['GET', 'POST']
    • save_headers - Due to memory constrains you most likely want to minimze memory usage by saving only headers which you really need in. E.g. for POST requests it is make sense to save at least 'Content-Length' header. Defaults to empty list - [].
    • max_body_size - Max HTTP body size (e.g. POST form data). Be careful with large forms due to memory constrains (especially with esp8266 which has 64K RAM). Defaults to 1024.
    • allowed_access_control_headers - Whenever you're using xmlHttpRequest (send JSON from browser) these headers are required to do access control. Defaults to *
    • allowed_access_control_origins - The same idea as for header above. Defaults to *.
  • @route - simple and useful decorator (inspired by Flask). Instead of using add_route() directly - just decorate your function with @route, like this:

    @app.route('/index.html')
    async def index(req, resp):
        await resp.send_file('static/index.simple.html')
    
  • add_resource(self, cls, url, **kwargs) - RestAPI: Map resource class cls to url. Class cls is arbitrary class with with implementation of HTTP methods:

    class CustomersList():
        def get(self, data):
            """Return list of all customers"""
            return {'1': {'name': 'Jack'}, '2': {'name': 'Bob'}}
    
        def post(self, data):
            """Add customer"""
            db[str(next_id)] = data
        return {'message': 'created'}, 201
    

    **kwargs are optional and will be passed to handler directly. Note: only GET, POST, PUT and DELETE methods are supported. Check restapi full example as well.

  • @resource - the same idea as for route but for resource:

    # Regular version
    @app.resource('/user/<id>')
    def user(data, id):
        return {'id': id, 'name': 'foo'}
    
    # Generator based / different HTTP method
    @app.resource('/user/<id>', method='POST')
    async def user(data, id):
        yield '{'
        yield '"id": "{}",'.format(id)
        yield '"name": "test",'
        yield '}'
    
  • run(self, host="127.0.0.1", port=8081, loop_forever=True, backlog=10) - run web server. Since tinyweb is fully async server by default it is blocking call assuming that you've added other tasks before.

    • host - host to listen on
    • port - port to listen on
    • loop_forever - run async.loop_forever(). Set to False if you don't want run to be blocking call. Be sure to call async.loop_forever() by yourself.
    • backlog - size of pending connections queue (basically argument to listen() function)
  • shutdown(self) - gracefully shutdown web server. Meaning close all active connections / server socket and cancel all started coroutines. NOTE be sure to it in event loop or run event loop at least once, like:

    async def all_shutdown():
        await asyncio.sleep_ms(100)
    
    try:
        web = tinyweb.webserver()
        web.run()
    except KeyboardInterrupt as e:
        print(' CTRL+C pressed - terminating...')
        web.shutdown()
        uasyncio.get_event_loop().run_until_complete(all_shutdown())
    

class request

This class contains everything about HTTP request. Use it to get HTTP headers / query string / etc. Warning - to improve memory / CPU usage strings in request class are binary strings. This means that you must use b prefix when accessing items, e.g.

>>> print(req.method)
b'GET'

So be sure to check twice your code which interacts with request class.

  • method - HTTP request method.

  • path - URL path.

  • query_string - URL path.

  • headers - dict of saved HTTP headers from request. **Only if enabled by save_headers.

    if b'Content-Length' in self.headers:
        print(self.headers[b'Content-Length'])
    
  • read_parse_form_data() - By default (again, to save CPU/memory) tinyweb doesn't read form data. You have to call it manually unless you're using RESTApi. Returns dict of key / value pairs.

class response

Use this class to generate HTTP response. Please be noticed that response class is using regular strings, not binary strings as request class does.

  • code - HTTP response code. By default set to 200 which means OK, no error.

  • version - HTTP version. Defaults to 1.0. Please be note - that only HTTP1.0 is internally supported by tinyweb. So if you changing it to 1.1 - be sure to support protocol by yourself.

  • headers - HTTP response headers dictionary (key / value pairs).

  • add_header(self, key, value) - Convenient way to add HTTP response header

    • key - Header name
    • value - Header value
  • add_access_control_headers(self) - Add HTTP headers required for RESTAPI (JSON query)

  • redirect(self, location) - Generate HTTP redirection (HTTP 302 Found) to location. This function is coroutine.

  • start_html(self)- Start response with HTML content type. This function is coroutine. This function is basically sends response line and headers. Refer to hello world example.

  • send(self, payload) - Sends your string/bytes payload to client. Be sure to start your response with start_html() or manually. This function is coroutine.

  • send_file(self, filename): Send local file as HTTP response. File type will be detected automatically unless you explicitly change it. If file doesn't exists - HTTP Error 404 will be generated. Additional keyword arguments

    • content_type - MIME filetype. By default - None which means autodetect.
    • content_encoding - Specifies used compression type, e.g. gzip. By default - None which means don't add this header.
    • max_age - Cache control. How long browser can keep this file on disk. Value is in seconds. By default - 30 days. To disable caching, set it to 0.
  • error(self, code) - Generate HTTP error response with error code. This function is coroutine.

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