Utilities

Broadcast

websockets.broadcast(websockets, message)

Broadcast a message to several WebSocket connections.

A string (str) is sent as a Text frame. A bytestring or bytes-like object (bytes, bytearray, or memoryview) is sent as a Binary frame.

broadcast() pushes the message synchronously to all connections even if their write buffers are overflowing. There’s no backpressure.

broadcast() skips silently connections that aren’t open in order to avoid errors on connections where the closing handshake is in progress.

If you broadcast messages faster than a connection can handle them, messages will pile up in its write buffer until the connection times out. Keep low values for ping_interval and ping_timeout to prevent excessive memory usage by slow connections when you use broadcast().

Unlike send(), broadcast() doesn’t support sending fragmented messages. Indeed, fragmentation is useful for sending large messages without buffering them in memory, while broadcast() buffers one copy per connection as fast as possible.

Parameters:

• websockets (Iterable[WebSocketCommonProtocol]) – WebSocket connections to which the message will be sent.

• message (Data) – message to send.

Raises:

• RuntimeError – if a connection is busy sending a fragmented message.

• TypeError – if message doesn’t have a supported type.

WebSocket events

class websockets.frames.Frame(opcode, data, fin=True, rsv1=False, rsv2=False, rsv3=False)

WebSocket frame.

opcode

Opcode.

Type:

websockets.frames.Opcode

data

Payload data.

Type:

bytes

fin

FIN bit.

Type:

bool

rsv1

RSV1 bit.

Type:

bool

rsv2

RSV2 bit.

Type:

bool

rsv3

RSV3 bit.

Type:

bool

Only these fields are needed. The MASK bit, payload length and masking-key are handled on the fly when parsing and serializing frames.

class websockets.frames.Opcode(value)

Opcode values for WebSocket frames.

CONT = 0

TEXT = 1

BINARY = 2

CLOSE = 8

PING = 9

PONG = 10

class websockets.frames.Close(code, reason)

Code and reason for WebSocket close frames.

code

Close code.

Type:

int

reason

Close reason.

Type:

str

HTTP events

class websockets.http11.Request(path, headers, _exception=None)

WebSocket handshake request.

path

Request path, including optional query.

Type:

str

headers

Request headers.

Type:

websockets.datastructures.Headers

class websockets.http11.Response(status_code, reason_phrase, headers, body=None, _exception=None)

WebSocket handshake response.

status_code

Response code.

Type:

int

reason_phrase

Response reason.

Type:

str

headers

Response headers.

Type:

websockets.datastructures.Headers

body

Response body, if any.

Type:

bytes | None

class websockets.datastructures.Headers(*args, **kwargs)

Efficient data structure for manipulating HTTP headers.

A list of (name, values) is inefficient for lookups.

A dict doesn’t suffice because header names are case-insensitive and multiple occurrences of headers with the same name are possible.

Headers stores HTTP headers in a hybrid data structure to provide efficient insertions and lookups while preserving the original data.

In order to account for multiple values with minimal hassle, Headers follows this logic:

• When getting a header with headers[name]:

  • if there’s no value, KeyError is raised;

  • if there’s exactly one value, it’s returned;

  • if there’s more than one value, MultipleValuesError is raised.

• When setting a header with headers[name] = value, the value is appended to the list of values for that header.

• When deleting a header with del headers[name], all values for that header are removed (this is slow).

Other methods for manipulating headers are consistent with this logic.

As long as no header occurs multiple times, Headers behaves like dict, except keys are lower-cased to provide case-insensitivity.

Two methods support manipulating multiple values explicitly:

• get_all() returns a list of all values for a header;

• raw_items() returns an iterator of (name, values) pairs.

get_all(key)

Return the (possibly empty) list of all values for a header.

Parameters:

key (str) – header name.

raw_items()

Return an iterator of all values as (name, value) pairs.

exception websockets.datastructures.MultipleValuesError

Exception raised when Headers has more than one value for a key.

URIs

websockets.uri.parse_uri(uri)

Parse and validate a WebSocket URI.

Parameters:

uri (str) – WebSocket URI.

Returns:

Parsed WebSocket URI.

Return type:

WebSocketURI

Raises:

InvalidURI – if uri isn’t a valid WebSocket URI.

class websockets.uri.WebSocketURI(secure, host, port, path, query, username=None, password=None)

WebSocket URI.

secure

True for a wss URI, False for a ws URI.

Type:

bool

host

Normalized to lower case.

Type:

str

port

Always set even if it’s the default.

Type:

int

path

May be empty.

Type:

str

query

May be empty if the URI doesn’t include a query component.

Type:

str

username

Available when the URI contains User Information.

Type:

str | None

password

Available when the URI contains User Information.

Type:

str | None