A wrapper for create_connection() returning a (reader, writer) pair.
The reader returned is a StreamReader instance; the writer is a StreamWriter instance.
The arguments are all the usual arguments to BaseEventLoop.create_connection() except protocol_factory; most common are positional host and port, with various optional keyword arguments following.
Additional optional keyword arguments are loop (to set the event loop instance to use) and limit (to set the buffer limit passed to the StreamReader).
(If you want to customize the StreamReader and/or StreamReaderProtocol classes, just copy the code – there’s really nothing special here except some convenience.)
This function returns a coroutine object.
Start a socket server, call back for each client connected.
The first parameter, client_connected_cb, takes two parameters: client_reader, client_writer. client_reader is a StreamReader object, while client_writer is a StreamWriter object. This parameter can either be a plain callback function or a coroutine function; if it is a coroutine function, it will be automatically converted into a Task.
The rest of the arguments are all the usual arguments to create_server() except protocol_factory; most common are positional host and port, with various optional keyword arguments following. The return value is the same as create_server().
Additional optional keyword arguments are loop (to set the event loop instance to use) and limit (to set the buffer limit passed to the StreamReader).
The return value is the same as create_server(), i.e. a AbstractServer object which can be used to stop the service.
This function returns a coroutine object.
Get the exception.
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Set the exception.
Set the transport.
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This method returns a coroutine object.
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This method returns a coroutine object.
Read exactly n bytes. Raise an IncompleteReadError if the end of the stream is reached before n can be read, the IncompleteReadError.partial attribute of the exception contains the partial read bytes.
This method returns a coroutine object.
Wraps a Transport.
This exposes write(), writelines(), can_write_eof(), write_eof(), get_extra_info() and close(). It adds drain() which returns an optional Future on which you can wait for flow control. It also adds a transport attribute which references the Transport directly.
Transport.
Return True if the transport supports write_eof(), False if not. See WriteTransport.can_write_eof().
Close the transport: see BaseTransport.close().
Wait until the write buffer of the underlying transport is flushed.
This method has an unusual return value. The intended use is to write:
w.write(data)
yield from w.drain()
When there’s nothing to wait for, drain() returns (), and the yield-from continues immediately. When the transport buffer is full (the protocol is paused), drain() creates and returns a Future and the yield-from will block until that Future is completed, which will happen when the buffer is (partially) drained and the protocol is resumed.
Return optional transport information: see BaseTransport.get_extra_info().
Write some data bytes to the transport: see WriteTransport.write().
Write a list (or any iterable) of data bytes to the transport: see WriteTransport.writelines().
Close the write end of the transport after flushing buffered data: see WriteTransport.write_eof().
Trivial helper class to adapt between Protocol and StreamReader. Sublclass of Protocol.
stream_reader is a StreamReader instance, client_connected_cb is an optional function called with (stream_reader, stream_writer) when a connection is made, loop is the event loop instance to use.
(This is a helper class instead of making StreamReader itself a Protocol subclass, because the StreamReader has other potential uses, and to prevent the user of the StreamReader to accidentally call inappropriate methods of the protocol.)
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Simple example querying HTTP headers of the URL passed on the command line:
import asyncio
import urllib.parse
import sys
@asyncio.coroutine
def print_http_headers(url):
url = urllib.parse.urlsplit(url)
reader, writer = yield from asyncio.open_connection(url.hostname, 80)
query = ('HEAD {url.path} HTTP/1.0\r\n'
'Host: {url.hostname}\r\n'
'\r\n').format(url=url)
writer.write(query.encode('latin-1'))
while True:
line = yield from reader.readline()
if not line:
break
line = line.decode('latin1').rstrip()
if line:
print('HTTP header> %s' % line)
url = sys.argv[1]
loop = asyncio.get_event_loop()
task = asyncio.async(print_http_headers(url))
loop.run_until_complete(task)
loop.close()
Usage:
python example.py http://example.com/path/page.html