sanic/docs/custom_protocol.md

Custom Protocol

You can change the behavior of protocol by using custom protocol.
If you want to use custom protocol, you should put subclass of protocol class in the protocol keyword argument of sanic.run(). The constructor of custom protocol class gets following keyword arguments from Sanic.

• loop
  loop is an asyncio compatible event loop.

• connections
  connections is a set object to store protocol objects. When Sanic receives SIGINT or SIGTERM, Sanic executes protocol.close_if_idle() for a protocol objects stored in connections.

• signal
  signal is a sanic.server.Signal object with stopped attribute. When Sanic receives SIGINT or SIGTERM, signal.stopped becomes True.

• request_handler
  request_handler is a coroutine that takes a sanic.request.Request object and a response callback as arguments.

• error_handler
  error_handler is a sanic.exceptions.Handler object.

• request_timeout
  request_timeout is seconds for timeout.

• request_max_size
  request_max_size is bytes of max request size.

Example

By default protocol, an error occurs, if the handler does not return an HTTPResponse object.
In this example, By rewriting write_response(), if the handler returns str, it will be converted to an HTTPResponse object.

from sanic import Sanic
from sanic.server import HttpProtocol
from sanic.response import text

app = Sanic(__name__)


class CustomHttpProtocol(HttpProtocol):

    def __init__(self, *, loop, request_handler, error_handler,
                 signal, connections, request_timeout, request_max_size):
        super().__init__(
            loop=loop, request_handler=request_handler,
            error_handler=error_handler, signal=signal,
            connections=connections, request_timeout=request_timeout,
            request_max_size=request_max_size)

    def write_response(self, response):
        if isinstance(response, str):
            response = text(response)
        self.transport.write(
            response.output(self.request.version)
        )
        self.transport.close()


@app.route('/')
async def string(request):
    return 'string'


@app.route('/1')
async def response(request):
    return text('response')

app.run(host='0.0.0.0', port=8000, protocol=CustomHttpProtocol)