Changelog
*********


8.1
===

*In development*


8.0.2
=====

* Restored the ability to pass a socket with the "sock" parameter of
  "serve()".

* Removed an incorrect assertion when a connection drops.


8.0.1
=====

* Restored the ability to import "WebSocketProtocolError" from
  "websockets".


8.0
===

Warning: **Version 8.0 drops compatibility with Python 3.4 and
  3.5.**

Note: **Version 8.0 expects** "process_request" **to be a
  coroutine.**Previously, it could be a function or a coroutine.If
  you're passing a "process_request" argument to "serve()" or
  "WebSocketServerProtocol", or if you're overriding
  "process_request()" in a subclass, define it with "async def"
  instead of "def".For backwards compatibility, functions are still
  mostly supported, but mixing functions and coroutines won't work in
  some inheritance scenarios.

Note: **Version 8.0 changes the behavior of the** "max_queue"
  **parameter.**If you were setting "max_queue=0" to make the queue of
  incoming messages unbounded, change it to "max_queue=None".

Note: **Version 8.0 deprecates the** "host" **,** "port" **, and**
  "secure" **attributes of** "WebSocketCommonProtocol".Use
  "local_address" in servers and "remote_address" in clients instead
  of "host" and "port".

Note: **Version 8.0 renames the** "WebSocketProtocolError"
  **exception** to "ProtocolError" **.**A "WebSocketProtocolError"
  alias provides backwards compatibility.

Note: **Version 8.0 adds the reason phrase to the return type of the
  low- level API** "read_response()" **.**

Also:

* "send()", "ping()", and "pong()" support bytes-like types
  "bytearray" and "memoryview" in addition to "bytes".

* Added "ConnectionClosedOK" and "ConnectionClosedError" subclasses
  of "ConnectionClosed" to tell apart normal connection termination
  from errors.

* Added "basic_auth_protocol_factory()" to enforce HTTP Basic Auth
  on the server side.

* "connect()" handles redirects from the server during the
  handshake.

* "connect()" supports overriding "host" and "port".

* Added "unix_connect()" for connecting to Unix sockets.

* Improved support for sending fragmented messages by accepting
  asynchronous iterators in "send()".

* Prevented spurious log messages about "ConnectionClosed"
  exceptions in keepalive ping task. If you were using
  "ping_timeout=None" as a workaround, you can remove it.

* Changed "WebSocketServer.close()" to perform a proper closing
  handshake instead of failing the connection.

* Avoided a crash when a "extra_headers" callable returns "None".

* Improved error messages when HTTP parsing fails.

* Enabled readline in the interactive client.

* Added type hints (**PEP 484**).

* Added a FAQ to the documentation.

* Added documentation for extensions.

* Documented how to optimize memory usage.

* Improved API documentation.


7.0
===

Warning: **Version 7.0 renames the** "timeout" **argument of**
  "serve()" **and** "connect()" **to** "close_timeout" **.**This
  prevents confusion with "ping_timeout".For backwards compatibility,
  "timeout" is still supported.

Warning: **Version 7.0 changes how a server terminates connections
  when it's closed with** "close()" **.**Previously, connections
  handlers were canceled. Now, connections are closed with close code
  1001 (going away). From the perspective of the connection handler,
  this is the same as if the remote endpoint was disconnecting. This
  removes the need to prepare for "CancelledError" in connection
  handlers.You can restore the previous behavior by adding the
  following line at the beginning of connection handlers:

     def handler(websocket, path):
         closed = asyncio.ensure_future(websocket.wait_closed())
         closed.add_done_callback(lambda task: task.cancel())

Note: **Version 7.0 changes how a** "ping()" **that hasn't received
  a pong yet behaves when the connection is closed.**The ping — as in
  "ping = await websocket.ping()" — used to be canceled when the
  connection is closed, so that "await ping" raised "CancelledError".
  Now "await ping" raises "ConnectionClosed" like other public APIs.

Note: **Version 7.0 raises a** "RuntimeError" **exception if two
  coroutines call** "recv()" **concurrently.**Concurrent calls lead to
  non-deterministic behavior because there are no guarantees about
  which coroutine will receive which message.

Also:

* "websockets" sends Ping frames at regular intervals and closes the
  connection if it doesn't receive a matching Pong frame. See
  "WebSocketCommonProtocol" for details.

* Added "process_request" and "select_subprotocol" arguments to
  "serve()" and "WebSocketServerProtocol" to customize
  "process_request()" and "select_subprotocol()" without subclassing
  "WebSocketServerProtocol".

* Added support for sending fragmented messages.

* Added the "wait_closed()" method to protocols.

* Added an interactive client: "python -m websockets <uri>".

* Changed the "origins" argument to represent the lack of an origin
  with "None" rather than "''".

* Fixed a data loss bug in "recv()": canceling it at the wrong time
  could result in messages being dropped.

* Improved handling of multiple HTTP headers with the same name.

* Improved error messages when a required HTTP header is missing.


6.0
===

Warning: **Version 6.0 introduces the** "Headers" **class for
  managing HTTP headers and changes several public APIs:**

  * "process_request()" now receives a "Headers" instead of a
    "HTTPMessage" in the "request_headers" argument.

  * The "request_headers" and "response_headers" attributes of
    "WebSocketCommonProtocol" are "Headers" instead of "HTTPMessage".

  * The "raw_request_headers" and "raw_response_headers" attributes
    of "WebSocketCommonProtocol" are removed. Use "raw_items()"
    instead.

  * Functions defined in the "handshake" module now receive
    "Headers" in argument instead of "get_header" or "set_header"
    functions. This affects libraries that rely on low-level APIs.

  * Functions defined in the "http" module now return HTTP headers
    as "Headers" instead of lists of "(name, value)" pairs.

  Since "Headers" and "HTTPMessage" provide similar APIs, this change
  won't affect most of the code dealing with HTTP headers.

Also:

* Added compatibility with Python 3.7.


5.0.1
=====

* Fixed a regression in the 5.0 release that broke some invocations
  of "serve()" and "connect()".


5.0
===

Note: **Version 5.0 fixes a security issue introduced in version
  4.0.**Version 4.0 was vulnerable to denial of service by memory
  exhaustion because it didn't enforce "max_size" when decompressing
  compressed messages (CVE-2018-1000518).

Note: **Version 5.0 adds a** "user_info" **field to the return value
  of** "parse_uri()" **and** "WebSocketURI" **.**If you're unpacking
  "WebSocketURI" into four variables, adjust your code to account for
  that fifth field.

Also:

* "connect()" performs HTTP Basic Auth when the URI contains
  credentials.

* Iterating on incoming messages no longer raises an exception when
  the connection terminates with close code 1001 (going away).

* A plain HTTP request now receives a 426 Upgrade Required response
  and doesn't log a stack trace.

* "unix_serve()" can be used as an asynchronous context manager on
  Python ≥ 3.5.1.

* Added the "closed" property to protocols.

* If a "ping()" doesn't receive a pong, it's canceled when the
  connection is closed.

* Reported the cause of "ConnectionClosed" exceptions.

* Added new examples in the documentation.

* Updated documentation with new features from Python 3.6.

* Improved several other sections of the documentation.

* Fixed missing close code, which caused "TypeError" on connection
  close.

* Fixed a race condition in the closing handshake that raised
  "InvalidState".

* Stopped logging stack traces when the TCP connection dies
  prematurely.

* Prevented writing to a closing TCP connection during unclean
  shutdowns.

* Made connection termination more robust to network congestion.

* Prevented processing of incoming frames after failing the
  connection.


4.0.1
=====

* Fixed issues with the packaging of the 4.0 release.


4.0
===

Warning: **Version 4.0 enables compression with the permessage-
  deflate extension.**In August 2017, Firefox and Chrome support it,
  but not Safari and IE.Compression should improve performance but it
  increases RAM and CPU use.If you want to disable compression, add
  "compression=None" when calling "serve()" or "connect()".

Warning: **Version 4.0 drops compatibility with Python 3.3.**

Note: **Version 4.0 removes the** "state_name" **attribute of
  protocols.**Use "protocol.state.name" instead of
  "protocol.state_name".

Also:

* "WebSocketCommonProtocol" instances can be used as asynchronous
  iterators on Python ≥ 3.6. They yield incoming messages.

* Added "unix_serve()" for listening on Unix sockets.

* Added the "sockets" attribute to the return value of "serve()".

* Reorganized and extended documentation.

* Aborted connections if they don't close within the configured
  "timeout".

* Rewrote connection termination to increase robustness in edge
  cases.

* Stopped leaking pending tasks when "cancel()" is called on a
  connection while it's being closed.

* Reduced verbosity of "Failing the WebSocket connection" logs.

* Allowed "extra_headers" to override "Server" and "User-Agent"
  headers.


3.4
===

* Renamed "serve()" and "connect()"'s "klass" argument to
  "create_protocol" to reflect that it can also be a callable. For
  backwards compatibility, "klass" is still supported.

* "serve()" can be used as an asynchronous context manager on Python
  ≥ 3.5.1.

* Added support for customizing handling of incoming connections
  with "process_request()".

* Made read and write buffer sizes configurable.

* Rewrote HTTP handling for simplicity and performance.

* Added an optional C extension to speed up low-level operations.

* An invalid response status code during "connect()" now raises
  "InvalidStatusCode" with a "code" attribute.

* Providing a "sock" argument to "connect()" no longer crashes.


3.3
===

* Ensured compatibility with Python 3.6.

* Reduced noise in logs caused by connection resets.

* Avoided crashing on concurrent writes on slow connections.


3.2
===

* Added "timeout", "max_size", and "max_queue" arguments to
  "connect()" and "serve()".

* Made server shutdown more robust.


3.1
===

* Avoided a warning when closing a connection before the opening
  handshake.

* Added flow control for incoming data.


3.0
===

Warning: **Version 3.0 introduces a backwards-incompatible change in
  the** "recv()" **API.****If you're upgrading from 2.x or earlier,
  please read this carefully.**"recv()" used to return "None" when the
  connection was closed. This required checking the return value of
  every call:

     message = await websocket.recv()
     if message is None:
         return

  Now it raises a "ConnectionClosed" exception instead. This is more
  Pythonic. The previous code can be simplified to:

     message = await websocket.recv()

  When implementing a server, which is the more popular use case,
  there's no strong reason to handle such exceptions. Let them bubble
  up, terminate the handler coroutine, and the server will simply
  ignore them.In order to avoid stranding projects built upon an
  earlier version, the previous behavior can be restored by passing
  "legacy_recv=True" to "serve()", "connect()",
  "WebSocketServerProtocol", or "WebSocketClientProtocol".
  "legacy_recv" isn't documented in their signatures but isn't
  scheduled for deprecation either.

Also:

* "connect()" can be used as an asynchronous context manager on
  Python ≥ 3.5.1.

* Updated documentation with "await" and "async" syntax from Python
  3.5.

* "ping()" and "pong()" support data passed as "str" in addition to
  "bytes".

* Worked around an asyncio bug affecting connection termination
  under load.

* Made "state_name" attribute on protocols a public API.

* Improved documentation.


2.7
===

* Added compatibility with Python 3.5.

* Refreshed documentation.


2.6
===

* Added "local_address" and "remote_address" attributes on
  protocols.

* Closed open connections with code 1001 when a server shuts down.

* Avoided TCP fragmentation of small frames.


2.5
===

* Improved documentation.

* Provided access to handshake request and response HTTP headers.

* Allowed customizing handshake request and response HTTP headers.

* Supported running on a non-default event loop.

* Returned a 403 status code instead of 400 when the request Origin
  isn't allowed.

* Canceling "recv()" no longer drops the next message.

* Clarified that the closing handshake can be initiated by the
  client.

* Set the close code and reason more consistently.

* Strengthened connection termination by simplifying the
  implementation.

* Improved tests, added tox configuration, and enforced 100% branch
  coverage.


2.4
===

* Added support for subprotocols.

* Supported non-default event loop.

* Added "loop" argument to "connect()" and "serve()".


2.3
===

* Improved compliance of close codes.


2.2
===

* Added support for limiting message size.


2.1
===

* Added "host", "port" and "secure" attributes on protocols.

* Added support for providing and checking Origin.


2.0
===

Warning: **Version 2.0 introduces a backwards-incompatible change in
  the** "send()", "ping()", and "pong()" **APIs.****If you're
  upgrading from 1.x or earlier, please read this carefully.**These
  APIs used to be functions. Now they're coroutines.Instead of:

     websocket.send(message)

  you must now write:

     await websocket.send(message)

Also:

* Added flow control for outgoing data.


1.0
===

* Initial public release.
