Client (threading)#
Opening a connection#
- websockets.sync.client.connect(uri, *, sock=None, ssl_context=None, server_hostname=None, origin=None, extensions=None, subprotocols=None, additional_headers=None, user_agent_header='Python/x.y.z websockets/X.Y', compression='deflate', open_timeout=10, close_timeout=10, max_size=2**20, logger=None, create_connection=None)#
Connect to the WebSocket server at
uri.This function returns a
ClientConnectioninstance, which you can use to send and receive messages.connect()may be used as a context manager:async with websockets.sync.client.connect(...) as websocket: ...
The connection is closed automatically when exiting the context.
- Parameters:
uri (str) – URI of the WebSocket server.
sock (socket | None) – Preexisting TCP socket.
sockoverrides the host and port fromuri. You may callsocket.create_connection()to create a suitable TCP socket.ssl_context (SSLContext | None) – Configuration for enabling TLS on the connection.
server_hostname (str | None) – Host name for the TLS handshake.
server_hostnameoverrides the host name fromuri.origin (Origin | None) – Value of the
Originheader, for servers that require it.extensions (Sequence[ClientExtensionFactory] | None) – List of supported extensions, in order in which they should be negotiated and run.
subprotocols (Sequence[Subprotocol] | None) – List of supported subprotocols, in order of decreasing preference.
additional_headers (HeadersLike | None) – Arbitrary HTTP headers to add to the handshake request.
user_agent_header (str | None) – Value of the
User-Agentrequest header. It defaults to"Python/x.y.z websockets/X.Y". Setting it toNoneremoves the header.compression (str | None) – The “permessage-deflate” extension is enabled by default. Set
compressiontoNoneto disable it. See the compression guide for details.open_timeout (float | None) – Timeout for opening the connection in seconds.
Nonedisables the timeout.close_timeout (float | None) – Timeout for closing the connection in seconds.
Nonedisables the timeout.max_size (int | None) – Maximum size of incoming messages in bytes.
Nonedisables the limit.logger (Logger | LoggerAdapter | None) – Logger for this client. It defaults to
logging.getLogger("websockets.client"). See the logging guide for details.create_connection (Type[ClientConnection] | None) – Factory for the
ClientConnectionmanaging the connection. Set it to a wrapper or a subclass to customize connection handling.
- Raises:
InvalidURI – If
uriisn’t a valid WebSocket URI.OSError – If the TCP connection fails.
InvalidHandshake – If the opening handshake fails.
TimeoutError – If the opening handshake times out.
- websockets.sync.client.unix_connect(path, uri=None, *, sock=None, ssl_context=None, server_hostname=None, origin=None, extensions=None, subprotocols=None, additional_headers=None, user_agent_header='Python/x.y.z websockets/X.Y', compression='deflate', open_timeout=10, close_timeout=10, max_size=2**20, logger=None, create_connection=None)#
Connect to a WebSocket server listening on a Unix socket.
This function is identical to
connect(), except for the additionalpathargument. It’s only available on Unix.It’s mainly useful for debugging servers listening on Unix sockets.
Using a connection#
- class websockets.sync.client.ClientConnection(socket, protocol, *, close_timeout=10)#
Threaded implementation of a WebSocket client connection.
ClientConnectionprovidesrecv()andsend()methods for receiving and sending messages.It supports iteration to receive messages:
for message in websocket: process(message)
The iterator exits normally when the connection is closed with close code 1000 (OK) or 1001 (going away) or without a close code. It raises a
ConnectionClosedErrorwhen the connection is closed with any other code.- Parameters:
socket (socket.socket) – Socket connected to a WebSocket server.
protocol (ClientProtocol) – Sans-I/O connection.
close_timeout (Optional[float]) – Timeout for closing the connection in seconds.
- for ... in __iter__()#
Iterate on incoming messages.
The iterator calls
recv()and yields messages in an infinite loop.It exits when the connection is closed normally. It raises a
ConnectionClosedErrorexception after a protocol error or a network failure.
- recv(timeout=None)#
Receive the next message.
When the connection is closed,
recv()raisesConnectionClosed. Specifically, it raisesConnectionClosedOKafter a normal closure andConnectionClosedErrorafter a protocol error or a network failure. This is how you detect the end of the message stream.If
timeoutisNone, block until a message is received. Iftimeoutis set and no message is received withintimeoutseconds, raiseTimeoutError. Settimeoutto0to check if a message was already received.If the message is fragmented, wait until all fragments are received, reassemble them, and return the whole message.
- Returns:
A string (
str) for a Text frame or a bytestring (bytes) for a Binary frame.- Raises:
ConnectionClosed – When the connection is closed.
RuntimeError – If two threads call
recv()orrecv_streaming()concurrently.
- Return type:
- for ... in recv_streaming()#
Receive the next message frame by frame.
If the message is fragmented, yield each fragment as it is received. The iterator must be fully consumed, or else the connection will become unusable.
recv_streaming()raises the same exceptions asrecv().- Returns:
An iterator of strings (
str) for a Text frame or bytestrings (bytes) for a Binary frame.- Raises:
ConnectionClosed – When the connection is closed.
RuntimeError – If two threads call
recv()orrecv_streaming()concurrently.
- Return type:
- send(message)#
Send a message.
A string (
str) is sent as a Text frame. A bytestring or bytes-like object (bytes,bytearray, ormemoryview) is sent as a Binary frame.send()also accepts an iterable of strings, bytestrings, or bytes-like objects to enable fragmentation. Each item is treated as a message fragment and sent in its own frame. All items must be of the same type, or elsesend()will raise aTypeErrorand the connection will be closed.send()rejects dict-like objects because this is often an error. (If you really want to send the keys of a dict-like object as fragments, call itskeys()method and pass the result tosend().)When the connection is closed,
send()raisesConnectionClosed. Specifically, it raisesConnectionClosedOKafter a normal connection closure andConnectionClosedErrorafter a protocol error or a network failure.- Parameters:
message (str | bytes | Iterable[str | bytes]) – Message to send.
- Raises:
ConnectionClosed – When the connection is closed.
RuntimeError – If a connection is busy sending a fragmented message.
TypeError – If
messagedoesn’t have a supported type.
- close(code=CloseCode.NORMAL_CLOSURE, reason='')#
Perform the closing handshake.
close()waits for the other end to complete the handshake, for the TCP connection to terminate, and for all incoming messages to be read withrecv().close()is idempotent: it doesn’t do anything once the connection is closed.
- ping(data=None)#
Send a Ping.
A ping may serve as a keepalive or as a check that the remote endpoint received all messages up to this point
- Parameters:
data (str | bytes | None) – Payload of the ping. A
strwill be encoded to UTF-8. IfdataisNone, the payload is four random bytes.- Returns:
An event that will be set when the corresponding pong is received. You can ignore it if you don’t intend to wait.
pong_event = ws.ping() pong_event.wait() # only if you want to wait for the pong
- Raises:
ConnectionClosed – When the connection is closed.
RuntimeError – If another ping was sent with the same data and the corresponding pong wasn’t received yet.
- Return type:
- pong(data=b'')#
Send a Pong.
An unsolicited pong may serve as a unidirectional heartbeat.
- Parameters:
data (str | bytes) – Payload of the pong. A
strwill be encoded to UTF-8.- Raises:
ConnectionClosed – When the connection is closed.
WebSocket connection objects also provide these attributes:
- logger: LoggerLike#
Logger for this connection.
- property local_address: Any#
Local address of the connection.
For IPv4 connections, this is a
(host, port)tuple.The format of the address depends on the address family. See
getsockname().
- property remote_address: Any#
Remote address of the connection.
For IPv4 connections, this is a
(host, port)tuple.The format of the address depends on the address family. See
getpeername().
The following attributes are available after the opening handshake, once the WebSocket connection is open:
- property subprotocol: Subprotocol | None#
Subprotocol negotiated during the opening handshake.
Noneif no subprotocol was negotiated.