sanic/docs/custom_protocol.md
2016-12-29 16:41:04 +09:00

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# 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](https://docs.python.org/3/library/asyncio-protocol.html#protocol-classes) 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`.
```python
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)
```