Provided by: python3-socketio_4.4.0-2_all bug

NAME

       python-socketio - python-socketio Documentation

       This  projects  implements  Socket.IO  clients  and  servers that can run standalone or integrated with a
       variety of Python web frameworks.

GETTING STARTED

   What is Socket.IO?
       Socket.IO is a transport protocol that enables real-time bidirectional event-based communication  between
       clients  (typically,  though  not always, web browsers) and a server. The official implementations of the
       client and server components are written in JavaScript. This package provides Python  implementations  of
       both, each with standard and asyncio variants.

   Client Examples
       The example that follows shows a simple Python client:

          import socketio

          sio = socketio.Client()

          @sio.event
          def connect():
              print('connection established')

          @sio.event
          def my_message(data):
              print('message received with ', data)
              sio.emit('my response', {'response': 'my response'})

          @sio.event
          def disconnect():
              print('disconnected from server')

          sio.connect('http://localhost:5000')
          sio.wait()

   Client Features
       • Can connect to other Socket.IO complaint servers besides the one in this package.

       • Compatible with Python 2.7 and 3.5+.

       • Two versions of the client, one for standard Python and another for asyncio.

       • Uses an event-based architecture implemented with decorators that hides the details of the protocol.

       • Implements HTTP long-polling and WebSocket transports.

       • Automatically reconnects to the server if the connection is dropped.

   Server Examples
       The following application is a basic server example that uses the Eventlet asynchronous server:

          import eventlet
          import socketio

          sio = socketio.Server()
          app = socketio.WSGIApp(sio, static_files={
              '/': {'content_type': 'text/html', 'filename': 'index.html'}
          })

          @sio.event
          def connect(sid, environ):
              print('connect ', sid)

          @sio.event
          def my_message(sid, data):
              print('message ', data)

          @sio.event
          def disconnect(sid):
              print('disconnect ', sid)

          if __name__ == '__main__':
              eventlet.wsgi.server(eventlet.listen(('', 5000)), app)

       Below is a similar application, coded for asyncio (Python 3.5+ only) and the Uvicorn web server:

          from aiohttp import web
          import socketio

          sio = socketio.AsyncServer()
          app = web.Application()
          sio.attach(app)

          async def index(request):
              """Serve the client-side application."""
              with open('index.html') as f:
                  return web.Response(text=f.read(), content_type='text/html')

          @sio.event
          def connect(sid, environ):
              print("connect ", sid)

          @sio.event
          async def chat_message(sid, data):
              print("message ", data)
              await sio.emit('reply', room=sid)

          @sio.event
          def disconnect(sid):
              print('disconnect ', sid)

          app.router.add_static('/static', 'static')
          app.router.add_get('/', index)

          if __name__ == '__main__':
              web.run_app(app)

   Server Features
       • Can connect to servers running other compliant Socket.IO clients besides the one in this package.

       • Compatible with Python 2.7 and Python 3.5+.

       • Two versions of the server, one for standard Python and another for asyncio.

       • Supports large number of clients even on modest hardware due to being asynchronous.

       • Can be hosted on any WSGI and ASGI web servers includind Gunicorn, Uvicorn, eventlet and gevent.

       • Can be integrated with WSGI applications written in frameworks such as Flask, Django, etc.

       • Can be integrated with aiohttp, sanic and tornado asyncio applications.

       • Broadcasting of messages to all connected clients, or to subsets of them assigned to "rooms".

       • Optional support for multiple servers, connected through a messaging queue such as Redis or RabbitMQ.

       • Send messages to clients from external processes, such as Celery workers or auxiliary scripts.

       • Event-based architecture implemented with decorators that hides the details of the protocol.

       • Support for HTTP long-polling and WebSocket transports.

       • Support for XHR2 and XHR browsers.

       • Support for text and binary messages.

       • Support for gzip and deflate HTTP compression.

       • Configurable CORS responses, to avoid cross-origin problems with browsers.

THE SOCKET.IO CLIENT

       This package contains two Socket.IO clients:

       • The socketio.Client() class creates a client compatible with the standard Python library.

       • The socketio.AsyncClient() class creates a client compatible with the asyncio package.

       The  methods  in  the  two clients are the same, with the only difference that in the asyncio client most
       methods are implemented as coroutines.

   Installation
       To install the standard Python client along with its dependencies, use the following command:

          pip install "python-socketio[client]"

       If instead you plan on using the asyncio client, then use this:

          pip install "python-socketio[asyncio_client]"

   Creating a Client Instance
       To instantiate an Socket.IO client, simply create an instance of the appropriate client class:

          import socketio

          # standard Python
          sio = socketio.Client()

          # asyncio
          sio = socketio.AsyncClient()

   Defining Event Handlers
       The Socket.IO protocol is event based. When a server wants to communicate  with  a  client  it  emits  an
       event.  Each event has a name, and a list of arguments. The client registers event handler functions with
       the socketio.Client.event() or socketio.Client.on() decorators:

          @sio.event
          def message(data):
              print('I received a message!')

          @sio.on('my message')
          def on_message(data):
              print('I received a message!')

       In the first example the event name is obtained from the name of the handler function. The second example
       is  slightly  more  verbose,  but  it  allows the event name to be different than the function name or to
       include characters that are illegal in function names, such as spaces.

       For the asyncio client, event handlers can be regular functions as above, or can also be coroutines:

          @sio.event
          async def message(data):
              print('I received a message!')

       The connect, connect_error and disconnect events are special;  they  are  invoked  automatically  when  a
       client connects or disconnects from the server:

          @sio.event
          def connect():
              print("I'm connected!")

          @sio.event
          def connect_error():
              print("The connection failed!")

          @sio.event
          def disconnect():
              print("I'm disconnected!")

       Note  that  the  disconnect  handler  is  invoked for application initiated disconnects, server initiated
       disconnects, or accidental disconnects, for example due  to  networking  failures.  In  the  case  of  an
       accidental  disconnection,  the  client  is  going to attempt to reconnect immediately after invoking the
       disconnect handler. As soon as the connection is re-established the connect handler will be invoked  once
       again.

       If the server includes arguments with an event, those are passed to the handler function as arguments.

   Connecting to a Server
       The connection to a server is established by calling the connect() method:

          sio.connect('http://localhost:5000')

       In the case of the asyncio client, the method is a coroutine:

          await sio.connect('http://localhost:5000')

       Upon  connection,  the  server assigns the client a unique session identifier.  The applicaction can find
       this identifier in the sid attribute:

          print('my sid is', sio.sid)

   Emitting Events
       The client can emit an event to the server using the emit() method:

          sio.emit('my message', {'foo': 'bar'})

       Or in the case of asyncio, as a coroutine:

          await sio.emit('my message', {'foo': 'bar'})

       The single argument provided to the method is the data that is passed on to the server. The data  can  be
       of  type  str,  bytes, dict, list or tuple. When sending a tuple, the elements in it need to be of any of
       the other four allowed types. The elements of the tuple will be  passed  as  multiple  arguments  to  the
       server-side event handler function.

       The emit() method can be invoked inside an event handler as a response to a server event, or in any other
       part of the application, including in background tasks.

   Event Callbacks
       When a server emits an event to a client, it can optionally provide a callback function, to be invoked as
       a  way  of  acknowledgment that the server has processed the event. While this is entirely managed by the
       server, the client can provide a list of return values that are to be passed on to the callback  function
       set up by the server. This is achieved simply by returning the desired values from the handler function:

          @sio.event
          def my_event(sid, data):
              # handle the message
              return "OK", 123

       Likewise,  the  client  can  request  a callback function to be invoked after the server has processed an
       event. The socketio.Server.emit() method has an optional callback argument that can be set to a callable.
       If this argument is given, the callable will be invoked after the server has processed the event, and any
       values returned by the server handler will be passed as arguments to this function.

   Namespaces
       The Socket.IO protocol supports multiple logical  connections,  all  multiplexed  on  the  same  physical
       connection. Clients can open multiple connections by specifying a different namespace on each. Namespaces
       use a path syntax starting with a forward slash. A list of namespaces can be given by the client  in  the
       connect()  call. For example, this example creates two logical connections, the default one plus a second
       connection under the /chat namespace:

          sio.connect('http://localhost:5000', namespaces=['/chat'])

       To define event handlers on a namespace, the namespace  argument  must  be  added  to  the  corresponding
       decorator:

          @sio.event(namespace='/chat')
          def my_custom_event(sid, data):
              pass

          @sio.on('connect', namespace='/chat')
          def on_connect():
              print("I'm connected to the /chat namespace!")

       Likewise, the client can emit an event to the server on a namespace by providing its in the emit() call:

          sio.emit('my message', {'foo': 'bar'}, namespace='/chat')

       If  the  namespaces argument of the connect() call isn't given, any namespaces used in event handlers are
       automatically connected.

   Class-Based Namespaces
       As an alternative to the decorator-based event handlers, the event handlers that belong  to  a  namespace
       can be created as methods of a subclass of socketio.ClientNamespace:

          class MyCustomNamespace(socketio.ClientNamespace):
              def on_connect(self):
                  pass

              def on_disconnect(self):
                  pass

              def on_my_event(self, data):
                  self.emit('my_response', data)

          sio.register_namespace(MyCustomNamespace('/chat'))

       For  asyncio  based  servers,  namespaces must inherit from socketio.AsyncClientNamespace, and can define
       event handlers as coroutines if desired:

          class MyCustomNamespace(socketio.AsyncClientNamespace):
              def on_connect(self):
                  pass

              def on_disconnect(self):
                  pass

              async def on_my_event(self, data):
                  await self.emit('my_response', data)

          sio.register_namespace(MyCustomNamespace('/chat'))

       When class-based namespaces are used, any events received by the client are dispatched to a method  named
       as  the  event  name  with  the on_ prefix. For example, event my_event will be handled by a method named
       on_my_event.  If an event is received for which there is no corresponding method defined in the namespace
       class, then the event is ignored. All event names used in class-based namespaces must use characters that
       are legal in method names.

       As a convenience to methods defined in a class-based namespace, the namespace instance includes  versions
       of  several  of  the  methods in the socketio.Client and socketio.AsyncClient classes that default to the
       proper namespace when the namespace argument is not given.

       In the case that an event has a handler in a class-based namespace, and also a  decorator-based  function
       handler, only the standalone function handler is invoked.

   Disconnecting from the Server
       At  any  time  the  client  can  request  to be disconnected from the server by invoking the disconnect()
       method:

          sio.disconnect()

       For the asyncio client this is a coroutine:

          await sio.disconnect()

   Managing Background Tasks
       When a client connection to the server is established, a few background tasks will be spawned to keep the
       connection alive and handle incoming events. The application running on the main thread is free to do any
       work, as this is not going to prevent the functioning of the Socket.IO client.

       If the application does not have anything to do in the main thread and  just  wants  to  wait  until  the
       connection with the server ends, it can call the wait() method:

          sio.wait()

       Or in the asyncio version:

          await sio.wait()

       For the convenience of the application, a helper function is provided to start a custom background task:

          def my_background_task(my_argument)
              # do some background work here!
              pass

          sio.start_background_task(my_background_task, 123)

       The  arguments  passed to this method are the background function and any positional or keyword arguments
       to invoke the function with.

       Here is the asyncio version:

          async def my_background_task(my_argument)
              # do some background work here!
              pass

          sio.start_background_task(my_background_task, 123)

       Note that this function is not a coroutine, since it does not wait for the background  function  to  end.
       The background function must be a coroutine.

       The  sleep()  method  is  a  second convenience function that is provided for the benefit of applications
       working with background tasks of their own:

          sio.sleep(2)

       Or for asyncio:

          await sio.sleep(2)

       The single argument passed to the method is the number of seconds to sleep for.

THE SOCKET.IO SERVER

       This package contains two Socket.IO servers:

       • The socketio.Server() class creates a server compatible with the Python standard library.

       • The socketio.AsyncServer() class creates a server compatible with the asyncio package.

       The methods in the two servers are the same, with the only difference that in  the  asyncio  server  most
       methods are implemented as coroutines.

   Installation
       To install the Socket.IO server along with its dependencies, use the following command:

          pip install python-socketio

       In  addition to the server, you will need to select an asynchronous framework or server to use along with
       it. The list of supported packages is covered in the Deployment Strategies section.

   Creating a Server Instance
       A Socket.IO server is an instance of class socketio.Server. This  instance  can  be  transformed  into  a
       standard WSGI application by wrapping it with the socketio.WSGIApp class:

          import socketio

          # create a Socket.IO server
          sio = socketio.Server()

          # wrap with a WSGI application
          app = socketio.WSGIApp(sio)

       For  asyncio  based  servers,  the  socketio.AsyncServer  class provides the same functionality, but in a
       coroutine friendly format. If desired, The  socketio.ASGIApp  class  can  transform  the  server  into  a
       standard ASGI application:

          # create a Socket.IO server
          sio = socketio.AsyncServer()

          # wrap with ASGI application
          app = socketio.ASGIApp(sio)

       These  two  wrappers  can  also  act  as  middlewares, forwarding any traffic that is not intended to the
       Socket.IO server to another application. This allows Socket.IO servers to integrate easily into  existing
       WSGI or ASGI applications:

          from wsgi import app  # a Flask, Django, etc. application
          app = socketio.WSGIApp(sio, app)

   Serving Static Files
       The  Engine.IO  server can be configured to serve static files to clients. This is particularly useful to
       deliver HTML, CSS and JavaScript files to clients when this package  is  used  without  a  companion  web
       framework.

       Static  files  are  configured  with  a  Python  dictionary in which each key/value pair is a static file
       mapping rule. In its simplest form, this dictionary has one or more static file URLs  as  keys,  and  the
       corresponding files in the server as values:

          static_files = {
              '/': 'latency.html',
              '/static/socket.io.js': 'static/socket.io.js',
              '/static/style.css': 'static/style.css',
          }

       With  this  example configuration, when the server receives a request for / (the root URL) it will return
       the contents of the file latency.html in the current directory, and will assign a content type  based  on
       the file extension, in this case text/html.

       Files  with  the  .html,  .css,  .js,  .json, .jpg, .png, .gif and .txt file extensions are automatically
       recognized and assigned the correct content type. For files with other file extensions or  with  no  file
       extension, the application/octet-stream content type is used as a default.

       If desired, an explicit content type for a static file can be given as follows:

          static_files = {
              '/': {'filename': 'latency.html', 'content_type': 'text/plain'},
          }

       It  is  also  possible to configure an entire directory in a single rule, so that all the files in it are
       served as static files:

          static_files = {
              '/static': './public',
          }

       In this example any files with URLs starting with /static will be served directly from the public  folder
       in   the  current  directory,  so  for  example,  the  URL  /static/index.html  will  return  local  file
       ./public/index.html and the URL /static/css/styles.css will return local file ./public/css/styles.css.

       If a URL that ends in a / is requested, then a default filename of index.html is appended to it.  In  the
       previous example, a request for the /static/ URL would return local file ./public/index.html. The default
       filename to serve for slash-ending URLs can be set in the static files dictionary with an empty key:

          static_files = {
              '/static': './public',
              '': 'image.gif',
          }

       With  this  configuration,  a  request  for  /static/  would  return  local  file  ./public/image.gif.  A
       non-standard content type can also be specified if needed:

          static_files = {
              '/static': './public',
              '': {'filename': 'image.gif', 'content_type': 'text/plain'},
          }

       The static file configuration dictionary is given as the static_files argument to the socketio.WSGIApp or
       socketio.ASGIApp classes:

          # for standard WSGI applications
          sio = socketio.Server()
          app = socketio.WSGIApp(sio, static_files=static_files)

          # for asyncio-based ASGI applications
          sio = socketio.AsyncServer()
          app = socketio.ASGIApp(sio, static_files=static_files)

       The routing precedence in these two classes is as follows:

       • First, the path is checked against the Socket.IO endpoint.

       • Next, the path is checked against the static file configuration, if present.

       • If the path did not match the Socket.IO endpoint or any static file, control is passed to the secondary
         application if configured, else a 404 error is returned.

       Note:  static  file serving is intended for development use only, and as such it lacks important features
       such as caching. Do not use in a production environment.

   Defining Event Handlers
       The Socket.IO protocol is event based. When a client wants to communicate with the  server  it  emits  an
       event.  Each event has a name, and a list of arguments. The server registers event handler functions with
       the socketio.Server.event() or socketio.Server.on() decorators:

          @sio.event
          def my_event(sid, data):
              pass

          @sio.on('my custom event')
          def another_event(sid, data):
              pass

       In the first example the event name is obtained from the name of the handler function. The second example
       is  slightly  more  verbose,  but  it  allows the event name to be different than the function name or to
       include characters that are illegal in function names, such as spaces.

       For asyncio servers, event handlers can optionally be given as coroutines:

          @sio.event
          async def my_event(sid, data):
              pass

       The sid argument is the Socket.IO session id, a unique identifier of  each  client  connection.  All  the
       events sent by a given client will have the same sid value.

       The  connect  and disconnect events are special; they are invoked automatically when a client connects or
       disconnects from the server:

          @sio.event
          def connect(sid, environ):
              print('connect ', sid)

          @sio.event
          def disconnect(sid):
              print('disconnect ', sid)

       The connect event is an ideal place to perform user authentication, and  any  necessary  mapping  between
       user  entities  in the application and the sid that was assigned to the client. The environ argument is a
       dictionary in standard WSGI format containing the request  information,  including  HTTP  headers.  After
       inspecting  the  request,  the  connect  event handler can return False to reject the connection with the
       client.

       Sometimes it is useful to pass data back to the client being rejected. In that case instead of  returning
       False  socketio.exceptions.ConnectionRefusedError can be raised, and all of its arguments will be sent to
       the client with the rejection message:

          @sio.event
          def connect(sid, environ):
              raise ConnectionRefusedError('authentication failed')

   Emitting Events
       Socket.IO is a bidirectional protocol, so at any time the server can  send  an  event  to  its  connected
       clients. The socketio.Server.emit() method is used for this task:

          sio.emit('my event', {'data': 'foobar'})

       Sometimes  the  server  may  want  to send an event just to a particular client.  This can be achieved by
       adding a room argument to the emit call:

          sio.emit('my event', {'data': 'foobar'}, room=user_sid)

       The socketio.Server.emit() method takes an event name, a message payload of type str, bytes,  list,  dict
       or tuple, and the recipient room. When sending a tuple, the elements in it need to be of any of the other
       four allowed types. The elements of the tuple will be passed as multiple  arguments  to  the  client-side
       event  handler  function. The room argument is used to identify the client that should receive the event,
       and is set to the sid value assigned to that client's connection with the server. When omitted, the event
       is broadcasted to all connected clients.

   Event Callbacks
       When  a client sends an event to the server, it can optionally provide a callback function, to be invoked
       as a way of acknowledgment that the server has processed the event. While this is entirely managed by the
       client, the server can provide a list of values that are to be passed on to the callback function, simply
       by returning them from the handler function:

          @sio.event
          def my_event(sid, data):
              # handle the message
              return "OK", 123

       Likewise, the server can request a callback function to be invoked after a client has processed an event.
       The  socketio.Server.emit()  method  has  an optional callback argument that can be set to a callable. If
       this argument is given, the callable will be invoked after the client has processed the  event,  and  any
       values returned by the client will be passed as arguments to this function. Using callback functions when
       broadcasting to multiple clients is not recommended, as the callback function will be  invoked  once  for
       each client that received the message.

   Namespaces
       The  Socket.IO  protocol  supports  multiple  logical  connections,  all multiplexed on the same physical
       connection. Clients can open multiple  connections  by  specifying  a  different  namespace  on  each.  A
       namespace  is  given by the client as a pathname following the hostname and port. For example, connecting
       to http://example.com:8000/chat would open a connection to the namespace /chat.

       Each namespace is handled independently from the others, with separate session IDs (sids), event handlers
       and  rooms.  It is important that applications that use multiple namespaces specify the correct namespace
       when setting up their event handlers and rooms, using the optional namespace argument  available  in  all
       the methods in the socketio.Server class:

          @sio.event(namespace='/chat')
          def my_custom_event(sid, data):
              pass

          @sio.on('my custom event', namespace='/chat')
          def my_custom_event(sid, data):
              pass

       When emitting an event, the namespace optional argument is used to specify which namespace to send it on.
       When the namespace argument is omitted, the default Socket.IO namespace, which is named /, is used.

   Class-Based Namespaces
       As an alternative to the decorator-based event handlers, the event handlers that belong  to  a  namespace
       can be created as methods of a subclass of socketio.Namespace:

          class MyCustomNamespace(socketio.Namespace):
              def on_connect(self, sid, environ):
                  pass

              def on_disconnect(self, sid):
                  pass

              def on_my_event(self, sid, data):
                  self.emit('my_response', data)

          sio.register_namespace(MyCustomNamespace('/test'))

       For  asyncio  based  severs,  namespaces  must inherit from socketio.AsyncNamespace, and can define event
       handlers as coroutines if desired:

          class MyCustomNamespace(socketio.AsyncNamespace):
              def on_connect(self, sid, environ):
                  pass

              def on_disconnect(self, sid):
                  pass

              async def on_my_event(self, sid, data):
                  await self.emit('my_response', data)

          sio.register_namespace(MyCustomNamespace('/test'))

       When class-based namespaces are used, any events received by the server are dispatched to a method  named
       as  the  event  name  with  the on_ prefix. For example, event my_event will be handled by a method named
       on_my_event.  If an event is received for which there is no corresponding method defined in the namespace
       class, then the event is ignored. All event names used in class-based namespaces must use characters that
       are legal in method names.

       As a convenience to methods defined in a class-based namespace, the namespace instance includes  versions
       of  several  of  the  methods in the socketio.Server and socketio.AsyncServer classes that default to the
       proper namespace when the namespace argument is not given.

       In the case that an event has a handler in a class-based namespace, and also a  decorator-based  function
       handler, only the standalone function handler is invoked.

       It  is important to note that class-based namespaces are singletons. This means that a single instance of
       a namespace class is used for all clients, and consequently, a namespace instance cannot be used to store
       client specific information.

   Rooms
       To  make  it easy for the server to emit events to groups of related clients, the application can put its
       clients into "rooms", and then address messages to these rooms.

       In the previous section the room argument of the socketio.SocketIO.emit() method was used to designate  a
       specific  client as the recipient of the event. This is because upon connection, a personal room for each
       client is created and named with the sid assigned to the connection. The  application  is  then  free  to
       create  additional  rooms and manage which clients are in them using the socketio.Server.enter_room() and
       socketio.Server.leave_room() methods. Clients can be in as many rooms as needed and can be moved  between
       rooms as often as necessary.

          @sio.event
          def begin_chat(sid):
             sio.enter_room(sid, 'chat_users')

           @sio.event
           def exit_chat(sid):
               sio.leave_room(sid, 'chat_users')

       In  chat  applications  it  is  often desired that an event is broadcasted to all the members of the room
       except one, which is the originator of the event such  as  a  chat  message.  The  socketio.Server.emit()
       method  provides  an  optional  skip_sid  argument to indicate a client that should be skipped during the
       broadcast.

          @sio.event
          def my_message(sid, data):
              sio.emit('my reply', data, room='chat_users', skip_sid=sid)

   User Sessions
       The server can maintain application-specific information in a user session dedicated  to  each  connected
       client.  Applications  can  use  the  user  session  to  write any details about the user that need to be
       preserved throughout the life of the connection, such as usernames or user ids.

       The save_session() and get_session() methods are used to store  and  retrieve  information  in  the  user
       session:

          @sio.event
          def connect(sid, environ):
              username = authenticate_user(environ)
              sio.save_session(sid, {'username': username})

          @sio.event
          def message(sid, data):
              session = sio.get_session(sid)
              print('message from ', session['username'])

       For the asyncio server, these methods are coroutines:

          @sio.event
          async def connect(sid, environ):
              username = authenticate_user(environ)
              await sio.save_session(sid, {'username': username})

          @sio.event
          async def message(sid, data):
              session = await sio.get_session(sid)
              print('message from ', session['username'])

       The session can also be manipulated with the session() context manager:

          @sio.event
          def connect(sid, environ):
              username = authenticate_user(environ)
              with sio.session(sid) as session:
                  session['username'] = username

          @sio.event
          def message(sid, data):
              with sio.session(sid) as session:
                  print('message from ', session['username'])

       For the asyncio server, an asynchronous context manager is used:

          @sio.event
          def connect(sid, environ):
              username = authenticate_user(environ)
              async with sio.session(sid) as session:
                  session['username'] = username

          @sio.event
          def message(sid, data):
              async with sio.session(sid) as session:
                  print('message from ', session['username'])

       The  get_session(),  save_session()  and  session()  methods take an optional namespace argument. If this
       argument isn't provided, the session is attached to the default namespace.

       Note: the contents of the user session are destroyed when the client  disconnects.  In  particular,  user
       session  contents  are  not preserved when a client reconnects after an unexpected disconnection from the
       server.

   Using a Message Queue
       When working with distributed applications, it is often necessary to  access  the  functionality  of  the
       Socket.IO from multiple processes. There are two specific use cases:

       • Applications  that  use  a  work  queues  such  as  Celery may need to emit an event to a client once a
         background job completes. The most convenient place to carry out this task is the worker  process  that
         handled this job.

       • Highly  available applications may want to use horizontal scaling of the Socket.IO server to be able to
         handle very large number of concurrent clients.

       As a solution to the above problems, the Socket.IO server can be configured to connect to a message queue
       such as Redis or RabbitMQ, to communicate with other related Socket.IO servers or auxiliary workers.

   Redis
       To use a Redis message queue, a Python Redis client must be installed:

          # socketio.Server class
          pip install redis

          # socketio.AsyncServer class
          pip install aioredis

       The  Redis  queue is configured through the socketio.RedisManager and socketio.AsyncRedisManager classes.
       These classes connect directly to the Redis store and use the queue's pub/sub functionality:

          # socketio.Server class
          mgr = socketio.RedisManager('redis://')
          sio = socketio.Server(client_manager=mgr)

          # socketio.AsyncServer class
          mgr = socketio.AsyncRedisManager('redis://')
          sio = socketio.AsyncServer(client_manager=mgr)

       The client_manager argument instructs the server to connect to the given message queue, and to coordinate
       with other processes connected to the queue.

   Kombu
       Kombu  is  a  Python  package  that  provides access to RabbitMQ and many other message queues. It can be
       installed with pip:

          pip install kombu

       To use RabbitMQ or other AMQP protocol compatible queues, that is the only required dependency.  But  for
       other message queues, Kombu may require additional packages. For example, to use a Redis queue via Kombu,
       the Python package for Redis needs to be installed as well:

          pip install redis

       The queue is configured through the socketio.KombuManager:

          mgr = socketio.KombuManager('amqp://')
          sio = socketio.Server(client_manager=mgr)

       The connection URL passed to the KombuManager  constructor  is  passed  directly  to  Kombu's  Connection
       object,  so  the  Kombu documentation should be consulted for information on how to build the correct URL
       for a given message queue.

       Note that Kombu currently does not support asyncio, so it cannot be used  with  the  socketio.AsyncServer
       class.

   Kafka
       Apache Kafka is supported through the kafka-python package:

          pip install kafka-python

       Access to Kafka is configured through the socketio.KafkaManager class:

          mgr = socketio.KafkaManager('kafka://')
          sio = socketio.Server(client_manager=mgr)

       Note  that  Kafka  currently does not support asyncio, so it cannot be used with the socketio.AsyncServer
       class.

   AioPika
       A RabbitMQ message queue is supported in asyncio applications through the AioPika package:: You  need  to
       install aio_pika with pip:

          pip install aio_pika

       The RabbitMQ queue is configured through the socketio.AsyncAioPikaManager class:

          mgr = socketio.AsyncAioPikaManager('amqp://')
          sio = socketio.AsyncServer(client_manager=mgr)

   Emitting from external processes
       To  have  a  process  other than a server connect to the queue to emit a message, the same client manager
       classes can be used as standalone objects. In this case, the write_only argument should be set to True to
       disable the creation of a listening thread, which only makes sense in a server. For example:

          # connect to the redis queue as an external process
          external_sio = socketio.RedisManager('redis://', write_only=True)

          # emit an event
          external_sio.emit('my event', data={'foo': 'bar'}, room='my room')

   Deployment Strategies
       The following sections describe a variety of deployment strategies for Socket.IO servers.

   Aiohttp
       Aiohttp  is a framework with support for HTTP and WebSocket, based on asyncio. Support for this framework
       is limited to Python 3.5 and newer.

       Instances of class socketio.AsyncServer will automatically use aiohttp for asynchronous operations if the
       library  is  installed.  To  request  its  use  explicitly,  the  async_mode  option  can be given in the
       constructor:

          sio = socketio.AsyncServer(async_mode='aiohttp')

       A server configured for aiohttp must be attached to an existing application:

          app = web.Application()
          sio.attach(app)

       The aiohttp application can define regular routes that will coexist with the Socket.IO server. A  typical
       pattern is to add routes that serve a client application and any associated static files.

       The aiohttp application is then executed in the usual manner:

          if __name__ == '__main__':
              web.run_app(app)

   Tornado
       Tornado  is  a  web  framework  with  support for HTTP and WebSocket. Support for this framework requires
       Python 3.5 and newer. Only Tornado version 5 and newer are supported, thanks  to  its  tight  integration
       with asyncio.

       Instances of class socketio.AsyncServer will automatically use tornado for asynchronous operations if the
       library is installed. To request  its  use  explicitly,  the  async_mode  option  can  be  given  in  the
       constructor:

          sio = socketio.AsyncServer(async_mode='tornado')

       A server configured for tornado must include a request handler for Socket.IO:

          app = tornado.web.Application(
              [
                  (r"/socketio.io/", socketio.get_tornado_handler(sio)),
              ],
              # ... other application options
          )

       The  tornado  application  can define other routes that will coexist with the Socket.IO server. A typical
       pattern is to add routes that serve a client application and any associated static files.

       The tornado application is then executed in the usual manner:

          app.listen(port)
          tornado.ioloop.IOLoop.current().start()

   Sanic
       Sanic is a very efficient asynchronous web server for Python 3.5 and newer.

       Instances of class socketio.AsyncServer will automatically use Sanic for asynchronous operations  if  the
       framework  is  installed.  To  request  its  use  explicitly,  the  async_mode option can be given in the
       constructor:

          sio = socketio.AsyncServer(async_mode='sanic')

       A server configured for aiohttp must be attached to an existing application:

          app = Sanic()
          sio.attach(app)

       The Sanic application can define regular routes that will coexist with the Socket.IO  server.  A  typical
       pattern is to add routes that serve a client application and any associated static files.

       The Sanic application is then executed in the usual manner:

          if __name__ == '__main__':
              app.run()

       It  has  been  reported  that the CORS support provided by the Sanic extension sanic-cors is incompatible
       with this package's own support for this protocol. To disable CORS support in this package and let  Sanic
       take full control, initialize the server as follows:

          sio = socketio.AsyncServer(async_mode='sanic', cors_allowed_origins=[])

       On  the Sanic side you will need to enable the CORS_SUPPORTS_CREDENTIALS setting in addition to any other
       configuration that you use:

          app.config['CORS_SUPPORTS_CREDENTIALS'] = True

   Uvicorn, Daphne, and other ASGI servers
       The socketio.ASGIApp class is an ASGI compatible application that can forward  Socket.IO  traffic  to  an
       socketio.AsyncServer instance:

          sio = socketio.AsyncServer(async_mode='asgi')
          app = socketio.ASGIApp(sio)

       The application can then be deployed with any ASGI compatible web server.

   Eventlet
       Eventlet  is  a  high  performance concurrent networking library for Python 2 and 3 that uses coroutines,
       enabling code to be written in the same style used with  the  blocking  standard  library  functions.  An
       Socket.IO server deployed with eventlet has access to the long-polling and WebSocket transports.

       Instances  of  class  socketio.Server  will automatically use eventlet for asynchronous operations if the
       library is installed. To request  its  use  explicitly,  the  async_mode  option  can  be  given  in  the
       constructor:

          sio = socketio.Server(async_mode='eventlet')

       A  server  configured  for  eventlet  is  deployed  as  a  regular  WSGI  application  using the provided
       socketio.WSGIApp:

          app = socketio.WSGIApp(sio)
          import eventlet
          eventlet.wsgi.server(eventlet.listen(('', 8000)), app)

   Eventlet with Gunicorn
       An alternative to running the eventlet WSGI server as above is to use gunicorn,  a  fully  featured  pure
       Python web server. The command to launch the application under gunicorn is shown below:

          $ gunicorn -k eventlet -w 1 module:app

       Due to limitations in its load balancing algorithm, gunicorn can only be used with one worker process, so
       the -w option cannot be set to a value higher than 1. A single eventlet worker can handle a large  number
       of concurrent clients, each handled by a greenlet.

       Eventlet  provides  a  monkey_patch()  function  that replaces all the blocking functions in the standard
       library with equivalent asynchronous versions. While python-socketio does not  require  monkey  patching,
       other libraries such as database drivers are likely to require it.

   Gevent
       Gevent  is  another  asynchronous  framework  based on coroutines, very similar to eventlet. An Socket.IO
       server deployed with gevent has access to the long-polling  transport.  If  project  gevent-websocket  is
       installed, the WebSocket transport is also available.

       Instances  of  class  socketio.Server  will  automatically  use gevent for asynchronous operations if the
       library is installed and eventlet is not installed. To request gevent  to  be  selected  explicitly,  the
       async_mode option can be given in the constructor:

          sio = socketio.Server(async_mode='gevent')

       A  server  configured  for  gevent  is  deployed  as  a  regular  WSGI  application  using  the  provided
       socketio.WSGIApp:

          app = socketio.WSGIApp(sio)
          from gevent import pywsgi
          pywsgi.WSGIServer(('', 8000), app).serve_forever()

       If the WebSocket transport is installed, then the server must be started as follows:

          from gevent import pywsgi
          from geventwebsocket.handler import WebSocketHandler
          app = socketio.WSGIApp(sio)
          pywsgi.WSGIServer(('', 8000), app,
                            handler_class=WebSocketHandler).serve_forever()

   Gevent with Gunicorn
       An alternative to running the gevent WSGI server as above is to  use  gunicorn,  a  fully  featured  pure
       Python web server. The command to launch the application under gunicorn is shown below:

          $ gunicorn -k gevent -w 1 module:app

       Or to include WebSocket:

          $ gunicorn -k geventwebsocket.gunicorn.workers.GeventWebSocketWorker -w 1 module: app

       Same as with eventlet, due to limitations in its load balancing algorithm, gunicorn can only be used with
       one worker process, so the -w option cannot be higher than 1. A single gevent worker can handle  a  large
       number of concurrent clients through the use of greenlets.

       Gevent  provides  a  monkey_patch()  function  that  replaces  all the blocking functions in the standard
       library with equivalent asynchronous versions. While python-socketio does not  require  monkey  patching,
       other libraries such as database drivers are likely to require it.

   uWSGI
       When  using  the  uWSGI  server  in  combination  with gevent, the Socket.IO server can take advantage of
       uWSGI's native WebSocket support.

       Instances of class socketio.Server will automatically use this option for asynchronous operations if both
       gevent  and  uWSGI  are  installed  and  eventlet  is  not  installed.  To request this asynchronous mode
       explicitly, the async_mode option can be given in the constructor:

          # gevent with uWSGI
          sio = socketio.Server(async_mode='gevent_uwsgi')

       A complete explanation of the configuration and usage of the uWSGI server is beyond  the  scope  of  this
       documentation.  The  uWSGI server is a fairly complex package that provides a large and comprehensive set
       of options. It must be compiled with WebSocket  and  SSL  support  for  the  WebSocket  transport  to  be
       available.  As  way  of  an  introduction, the following command starts a uWSGI server for the latency.py
       example on port 5000:

          $ uwsgi --http :5000 --gevent 1000 --http-websockets --master --wsgi-file latency.py --callable app

   Standard Threads
       While not comparable to eventlet and gevent in terms of performance, the Socket.IO  server  can  also  be
       configured  to  work  with  multi-threaded web servers that use standard Python threads. This is an ideal
       setup to use with development servers such as Werkzeug. Only  the  long-polling  transport  is  currently
       available when using standard threads.

       Instances  of  class  socketio.Server  will  automatically use the threading mode if neither eventlet nor
       gevent are not installed. To request the threading mode explicitly, the async_mode option can be given in
       the constructor:

          sio = socketio.Server(async_mode='threading')

       A  server  configured  for  threading  is deployed as a regular web application, using any WSGI complaint
       multi-threaded server. The example below deploys an Socket.IO  application  combined  with  a  Flask  web
       application, using Flask's development web server based on Werkzeug:

          sio = socketio.Server(async_mode='threading')
          app = Flask(__name__)
          app.wsgi_app = socketio.WSGIApp(sio, app.wsgi_app)

          # ... Socket.IO and Flask handler functions ...

          if __name__ == '__main__':
              app.run(threaded=True)

       When  using  the  threading  mode,  it  is  important  to ensure that the WSGI server can handle multiple
       concurrent requests using threads, since a client can have up to two outstanding requests  at  any  given
       time. The Werkzeug server is single-threaded by default, so the threaded=True option is required.

       Note  that  servers  that  use  worker  processes  instead of threads, such as gunicorn, do not support a
       Socket.IO server configured in threading mode.

   Scalability Notes
       Socket.IO is a stateful protocol, which makes horizontal scaling more difficult. To deploy a  cluster  of
       Socket.IO processes hosted on one or multiple servers, the following conditions must be met:

       • Each  Socket.IO process must be able to handle multiple requests concurrently. This is required because
         long-polling clients send two requests in parallel. Worker processes that can only handle  one  request
         at a time are not supported.

       • The  load  balancer  must  be  configured  to  always forward requests from a client to the same worker
         process. Load balancers call this sticky sessions, or session affinity.

       • The worker processes need to communicate with each other  to  coordinate  complex  operations  such  as
         broadcasts.  This  is  done through a configured message queue. See the section on using message queues
         for details.

   Cross-Origin Controls
       For security reasons, this server enforces a same-origin policy by  default.  In  practical  terms,  this
       means the following:

       • If  an incoming HTTP or WebSocket request includes the Origin header, this header must match the scheme
         and host of the connection URL. In case of a mismatch, a 400 status code response is returned  and  the
         connection is rejected.

       • No restrictions are imposed on incoming requests that do not include the Origin header.

       If  necessary,  the  cors_allowed_origins option can be used to allow other origins. This argument can be
       set to a string to set a single allowed origin, or to a list to allow multiple origins. A  special  value
       of  '*'  can  be  used to instruct the server to allow all origins, but this should be done with care, as
       this could make the server vulnerable to Cross-Site Request Forgery (CSRF) attacks.

API REFERENCE

   Client class
       class       socketio.Client(reconnection=True,       reconnection_attempts=0,       reconnection_delay=1,
       reconnection_delay_max=5, randomization_factor=0.5, logger=False, binary=False, json=None, **kwargs)
              A Socket.IO client.

              This  class  implements  a  fully  compliant  Socket.IO  web client with support for websocket and
              long-polling transports.

              Parametersreconnection -- True if the client should  automatically  attempt  to  reconnect  to  the
                       server after an interruption, or False to not reconnect. The default is True.

                     • reconnection_attempts  --  How many reconnection attempts to issue before giving up, or 0
                       for infinity attempts.  The default is 0.

                     • reconnection_delay -- How long to wait in seconds before the first reconnection  attempt.
                       Each successive attempt doubles this delay.

                     • reconnection_delay_max -- The maximum delay between reconnection attempts.

                     • randomization_factor   --  Randomization  amount  for  each  delay  between  reconnection
                       attempts. The default is 0.5, which means that each delay is  randomly  adjusted  by  +/-
                       50%.

                     • logger  --  To  enable  logging  set  to  True or pass a logger object to use. To disable
                       logging set to False. The default is False.

                     • binary -- True to support binary payloads, False to treat all payloads as text. On Python
                       2,  if  this is set to True, unicode values are treated as text, and str and bytes values
                       are treated as binary.  This option has no effect on Python  3,  where  text  and  binary
                       payloads are always automatically discovered.

                     • json  -- An alternative json module to use for encoding and decoding packets. Custom json
                       modules must have dumps and loads functions that are compatible with the standard library
                       versions.

              The Engine.IO configuration supports the following settings:

              Parametersrequest_timeout -- A timeout in seconds for requests. The default is 5 seconds.

                     • ssl_verify  --  True  to  verify  SSL  certificates,  or  False  to  skip SSL certificate
                       verification, allowing connections to servers with self signed certificates.  The default
                       is True.

                     • engineio_logger  --  To  enable  Engine.IO logging set to True or pass a logger object to
                       use. To disable logging set to False. The default is False.

              call(event, data=None, namespace=None, timeout=60)
                     Emit a custom event to a client and wait for the response.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • timeout  --  The  waiting  timeout.  If  the  timeout is reached before the client
                              acknowledges the event, then a TimeoutError exception is raised.

              connect(url, headers={}, transports=None, namespaces=None, socketio_path='socket.io')
                     Connect to a Socket.IO server.

                     Parametersurl -- The URL of the  Socket.IO  server.  It  can  include  custom  query  string
                              parameters if required by the server.

                            • headers -- A dictionary with custom headers to send with the connection request.

                            • transports  --  The list of allowed transports. Valid transports are 'polling' and
                              'websocket'. If not given, the polling  transport  is  connected  first,  then  an
                              upgrade to websocket is attempted.

                            • namespaces -- The list of custom namespaces to connect, in addition to the default
                              namespace. If not given, the namespace list is obtained from the registered  event
                              handlers.

                            • socketio_path -- The endpoint where the Socket.IO server is installed. The default
                              value is appropriate for most cases.

                     Example usage:

                        sio = socketio.Client()
                        sio.connect('http://localhost:5000')

              disconnect()
                     Disconnect from the server.

              emit(event, data=None, namespace=None, callback=None)
                     Emit a custom event to one or more connected clients.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

              event(*args, **kwargs)
                     Decorator to register an event handler.

                     This is a simplified version of the  on()  method  that  takes  the  event  name  from  the
                     decorated function.

                     Example usage:

                        @sio.event
                        def my_event(data):
                            print('Received data: ', data)

                     The above example is equivalent to:

                        @sio.on('my_event')
                        def my_event(data):
                            print('Received data: ', data)

                     A custom namespace can be given as an argument to the decorator:

                        @sio.event(namespace='/test')
                        def my_event(data):
                            print('Received data: ', data)

              on(event, handler=None, namespace=None)
                     Register an event handler.

                     Parametersevent  --  The  event  name.  It  can  be  any  string. The event names 'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • handler -- The function that should be invoked to  handle  the  event.  When  this
                              parameter is not given, the method acts as a decorator for the handler function.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the handler is associated with the default namespace.

                     Example usage:

                        # as a decorator:
                        @sio.on('connect')
                        def connect_handler():
                            print('Connected!')

                        # as a method:
                        def message_handler(msg):
                            print('Received message: ', msg)
                            sio.send( 'response')
                        sio.on('message', message_handler)

                     The 'connect' event handler receives no arguments. The 'message' handler and  handlers  for
                     custom event names receive the message payload as only argument. Any values returned from a
                     message handler will be passed to the client's  acknowledgement  callback  function  if  it
                     exists. The 'disconnect' handler does not take arguments.

              register_namespace(namespace_handler)
                     Register a namespace handler object.

                     Parameters
                            namespace_handler  -- An instance of a Namespace subclass that handles all the event
                            traffic for a namespace.

              send(data, namespace=None, callback=None)
                     Send a message to one or more connected clients.

                     This function emits an event with the name 'message'. Use  emit()  to  issue  custom  event
                     names.

                     Parametersdata -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

              sleep(seconds=0)
                     Sleep for the requested amount of time using the appropriate async model.

                     This is a utility function that applications can use to put a task to sleep without  having
                     to worry about using the correct call for the selected async mode.

              start_background_task(target, *args, **kwargs)
                     Start a background task using the appropriate async model.

                     This  is  a utility function that applications can use to start a background task using the
                     method that is compatible with the selected async mode.

                     Parameterstarget -- the target function to execute.

                            • args -- arguments to pass to the function.

                            • kwargs -- keyword arguments to pass to the function.

                     This function returns an object compatible with the Thread class  in  the  Python  standard
                     library. The start() method on this object is already called by this function.

              transport()
                     Return the name of the transport used by the client.

                     The two possible values returned by this function are 'polling' and 'websocket'.

              wait() Wait until the connection with the server ends.

                     Client  applications  can use this function to block the main thread during the life of the
                     connection.

   AsyncClient class
       class     socketio.AsyncClient(reconnection=True,     reconnection_attempts=0,      reconnection_delay=1,
       reconnection_delay_max=5, randomization_factor=0.5, logger=False, binary=False, json=None, **kwargs)
              A Socket.IO client for asyncio.

              This  class  implements  a  fully  compliant  Socket.IO  web client with support for websocket and
              long-polling transports.

              Parametersreconnection -- True if the client should  automatically  attempt  to  reconnect  to  the
                       server after an interruption, or False to not reconnect. The default is True.

                     • reconnection_attempts  --  How many reconnection attempts to issue before giving up, or 0
                       for infinity attempts.  The default is 0.

                     • reconnection_delay -- How long to wait in seconds before the first reconnection  attempt.
                       Each successive attempt doubles this delay.

                     • reconnection_delay_max -- The maximum delay between reconnection attempts.

                     • randomization_factor   --  Randomization  amount  for  each  delay  between  reconnection
                       attempts. The default is 0.5, which means that each delay is  randomly  adjusted  by  +/-
                       50%.

                     • logger  --  To  enable  logging  set  to  True or pass a logger object to use. To disable
                       logging set to False. The default is False.

                     • binary -- True to support binary payloads, False to treat all payloads as text. On Python
                       2,  if  this is set to True, unicode values are treated as text, and str and bytes values
                       are treated as binary.  This option has no effect on Python  3,  where  text  and  binary
                       payloads are always automatically discovered.

                     • json  -- An alternative json module to use for encoding and decoding packets. Custom json
                       modules must have dumps and loads functions that are compatible with the standard library
                       versions.

              The Engine.IO configuration supports the following settings:

              Parametersrequest_timeout -- A timeout in seconds for requests. The default is 5 seconds.

                     • ssl_verify  --  True  to  verify  SSL  certificates,  or  False  to  skip SSL certificate
                       verification, allowing connections to servers with self signed certificates.  The default
                       is True.

                     • engineio_logger  --  To  enable  Engine.IO logging set to True or pass a logger object to
                       use. To disable logging set to False. The default is False.

              call(event, data=None, namespace=None, timeout=60)
                     Emit a custom event to a client and wait for the response.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • timeout  --  The  waiting  timeout.  If  the  timeout is reached before the client
                              acknowledges the event, then a TimeoutError exception is raised.

                     Note: this method is a coroutine.

              connect(url, headers={}, transports=None, namespaces=None, socketio_path='socket.io')
                     Connect to a Socket.IO server.

                     Parametersurl -- The URL of the  Socket.IO  server.  It  can  include  custom  query  string
                              parameters if required by the server.

                            • headers -- A dictionary with custom headers to send with the connection request.

                            • transports  --  The list of allowed transports. Valid transports are 'polling' and
                              'websocket'. If not given, the polling  transport  is  connected  first,  then  an
                              upgrade to websocket is attempted.

                            • namespaces -- The list of custom namespaces to connect, in addition to the default
                              namespace. If not given, the namespace list is obtained from the registered  event
                              handlers.

                            • socketio_path -- The endpoint where the Socket.IO server is installed. The default
                              value is appropriate for most cases.

                     Note: this method is a coroutine.

                     Example usage:

                        sio = socketio.Client()
                        sio.connect('http://localhost:5000')

              disconnect()
                     Disconnect from the server.

                     Note: this method is a coroutine.

              emit(event, data=None, namespace=None, callback=None)
                     Emit a custom event to one or more connected clients.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

                     Note: this method is a coroutine.

              event(*args, **kwargs)
                     Decorator to register an event handler.

                     This is a simplified version of the  on()  method  that  takes  the  event  name  from  the
                     decorated function.

                     Example usage:

                        @sio.event
                        def my_event(data):
                            print('Received data: ', data)

                     The above example is equivalent to:

                        @sio.on('my_event')
                        def my_event(data):
                            print('Received data: ', data)

                     A custom namespace can be given as an argument to the decorator:

                        @sio.event(namespace='/test')
                        def my_event(data):
                            print('Received data: ', data)

              on(event, handler=None, namespace=None)
                     Register an event handler.

                     Parametersevent  --  The  event  name.  It  can  be  any  string. The event names 'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • handler -- The function that should be invoked to  handle  the  event.  When  this
                              parameter is not given, the method acts as a decorator for the handler function.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the handler is associated with the default namespace.

                     Example usage:

                        # as a decorator:
                        @sio.on('connect')
                        def connect_handler():
                            print('Connected!')

                        # as a method:
                        def message_handler(msg):
                            print('Received message: ', msg)
                            sio.send( 'response')
                        sio.on('message', message_handler)

                     The 'connect' event handler receives no arguments. The 'message' handler and  handlers  for
                     custom event names receive the message payload as only argument. Any values returned from a
                     message handler will be passed to the client's  acknowledgement  callback  function  if  it
                     exists. The 'disconnect' handler does not take arguments.

              register_namespace(namespace_handler)
                     Register a namespace handler object.

                     Parameters
                            namespace_handler  -- An instance of a Namespace subclass that handles all the event
                            traffic for a namespace.

              send(data, namespace=None, callback=None)
                     Send a message to one or more connected clients.

                     This function emits an event with the name 'message'. Use  emit()  to  issue  custom  event
                     names.

                     Parametersdata -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

                     Note: this method is a coroutine.

              sleep(seconds=0)
                     Sleep for the requested amount of time using the appropriate async model.

                     This is a utility function that applications can use to put a task to sleep without  having
                     to worry about using the correct call for the selected async mode.

                     Note: this method is a coroutine.

              start_background_task(target, *args, **kwargs)
                     Start a background task using the appropriate async model.

                     This  is  a utility function that applications can use to start a background task using the
                     method that is compatible with the selected async mode.

                     Parameterstarget -- the target function to execute.

                            • args -- arguments to pass to the function.

                            • kwargs -- keyword arguments to pass to the function.

                     This function returns an object compatible with the Thread class  in  the  Python  standard
                     library. The start() method on this object is already called by this function.

              transport()
                     Return the name of the transport used by the client.

                     The two possible values returned by this function are 'polling' and 'websocket'.

              wait() Wait until the connection with the server ends.

                     Client  applications  can use this function to block the main thread during the life of the
                     connection.

                     Note: this method is a coroutine.

   Server class
       class socketio.Server(client_manager=None, logger=False,  binary=False,  json=None,  async_handlers=True,
       always_connect=False, **kwargs)
              A Socket.IO server.

              This  class  implements  a  fully  compliant  Socket.IO  web server with support for websocket and
              long-polling transports.

              Parametersclient_manager -- The client manager instance that will manage the client list. When this
                       is  omitted,  the client list is stored in an in-memory structure, so the use of multiple
                       connected servers is not possible.

                     • logger -- To enable logging set to True or pass  a  logger  object  to  use.  To  disable
                       logging set to False. The default is False.

                     • binary -- True to support binary payloads, False to treat all payloads as text. On Python
                       2, if this is set to True, unicode values are treated as text, and str and  bytes  values
                       are  treated  as  binary.   This  option has no effect on Python 3, where text and binary
                       payloads are always automatically discovered.

                     • json -- An alternative json module to use for encoding and decoding packets. Custom  json
                       modules must have dumps and loads functions that are compatible with the standard library
                       versions.

                     • async_handlers -- If set to True, event handlers for a client are  executed  in  separate
                       threads. To run handlers for a client synchronously, set to False. The default is True.

                     • always_connect  --  When  set  to  False, new connections are provisory until the connect
                       handler returns something other than False, at which point they are accepted. When set to
                       True, connections are immediately accepted, and then if the connect handler returns False
                       a disconnect is issued.  Set to True if you need to emit events from the connect  handler
                       and your client is confused when it receives events before the connection acceptance.  In
                       any other case use the default of False.

                     • kwargs -- Connection parameters for the underlying Engine.IO server.

              The Engine.IO configuration supports the following settings:

              Parametersasync_mode --  The  asynchronous  model  to  use.  See  the  Deployment  section  in  the
                       documentation  for  a  description  of  the  available  options.  Valid  async  modes are
                       "threading", "eventlet", "gevent" and "gevent_uwsgi". If  this  argument  is  not  given,
                       "eventlet"  is  tried first, then "gevent_uwsgi", then "gevent", and finally "threading".
                       The first async mode that has all its dependencies installed is then one that is chosen.

                     • ping_timeout -- The time in seconds that the client  waits  for  the  server  to  respond
                       before disconnecting. The default is 60 seconds.

                     • ping_interval  --  The  interval  in  seconds  at  which the client pings the server. The
                       default is 25 seconds.

                     • max_http_buffer_size -- The maximum size of a message when using the  polling  transport.
                       The default is 100,000,000 bytes.

                     • allow_upgrades -- Whether to allow transport upgrades or not. The default is True.

                     • http_compression  --  Whether  to compress packages when using the polling transport. The
                       default is True.

                     • compression_threshold -- Only compress messages when their byte size is greater than this
                       value. The default is 1024 bytes.

                     • cookie  -- Name of the HTTP cookie that contains the client session id. If set to None, a
                       cookie is not sent to the client.  The default is 'io'.

                     • cors_allowed_origins -- Origin or list of origins that are allowed  to  connect  to  this
                       server. Only the same origin is allowed by default. Set this argument to '*' to allow all
                       origins, or to [] to disable CORS handling.

                     • cors_credentials -- Whether credentials (cookies, authentication) are allowed in requests
                       to this server. The default is True.

                     • monitor_clients  --  If  set  to True, a background task will ensure inactive clients are
                       closed. Set to False to disable the monitoring task (not  recommended).  The  default  is
                       True.

                     • engineio_logger  --  To  enable  Engine.IO logging set to True or pass a logger object to
                       use. To disable logging set to False. The default is False.

              call(event, data=None, to=None, sid=None, namespace=None, timeout=60, **kwargs)
                     Emit a custom event to a client and wait for the response.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • to -- The session ID of the recipient client.

                            • sid -- Alias for the to parameter.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • timeout  --  The  waiting  timeout.  If  the  timeout is reached before the client
                              acknowledges the event, then a TimeoutError exception is raised.

                            • ignore_queue -- Only used when a message queue is configured. If set to True,  the
                              event is emitted to the client directly, without going through the queue.  This is
                              more efficient, but only works when  a  single  server  process  is  used.  It  is
                              recommended to always leave this parameter with its default value of False.

              close_room(room, namespace=None)
                     Close a room.

                     This function removes all the clients from the given room.

                     Parametersroom -- Room name.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the default namespace is used.

              disconnect(sid, namespace=None)
                     Disconnect a client.

                     Parameterssid -- Session ID of the client.

                            • namespace -- The Socket.IO namespace to disconnect. If this  argument  is  omitted
                              the default namespace is used.

              emit(event, data=None, to=None, room=None, skip_sid=None, namespace=None, callback=None, **kwargs)
                     Emit a custom event to one or more connected clients.

                     Parametersevent  --  The  event  name.  It  can  be  any  string. The event names 'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • to  -- The recipient of the message. This can be set to the session ID of a client
                              to address only that client, or to to any custom room created by  the  application
                              to  address all the clients in that room, If this argument is omitted the event is
                              broadcasted to all connected clients.

                            • room -- Alias for the to parameter.

                            • skip_sid -- The session ID of a client to skip when broadcasting to a room  or  to
                              all  clients. This can be used to prevent a message from being sent to the sender.
                              To skip multiple sids, pass a list.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

                            • ignore_queue -- Only used when a message queue is configured. If set to True,  the
                              event  is  emitted to the clients directly, without going through the queue.  This
                              is more efficient, but only works when a single server  process  is  used.  It  is
                              recommended to always leave this parameter with its default value of False.

              enter_room(sid, room, namespace=None)
                     Enter a room.

                     This  function  adds  the  client to a room. The emit() and send() functions can optionally
                     broadcast events to all the clients in a room.

                     Parameterssid -- Session ID of the client.

                            • room -- Room name. If the room does not exist it is created.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the default namespace is used.

              event(*args, **kwargs)
                     Decorator to register an event handler.

                     This  is  a  simplified  version  of  the  on()  method  that takes the event name from the
                     decorated function.

                     Example usage:

                        @sio.event
                        def my_event(data):
                            print('Received data: ', data)

                     The above example is equivalent to:

                        @sio.on('my_event')
                        def my_event(data):
                            print('Received data: ', data)

                     A custom namespace can be given as an argument to the decorator:

                        @sio.event(namespace='/test')
                        def my_event(data):
                            print('Received data: ', data)

              get_session(sid, namespace=None)
                     Return the user session for a client.

                     Parameterssid -- The session id of the client.

                            • namespace -- The Socket.IO namespace. If this  argument  is  omitted  the  default
                              namespace is used.

                     The  return value is a dictionary. Modifications made to this dictionary are not guaranteed
                     to be preserved unless save_session() is called, or when the  session  context  manager  is
                     used.

              handle_request(environ, start_response)
                     Handle an HTTP request from the client.

                     This  is  the  entry point of the Socket.IO application, using the same interface as a WSGI
                     application. For the typical usage, this function is invoked by  the  Middleware  instance,
                     but it can be invoked directly when the middleware is not used.

                     Parametersenviron -- The WSGI environment.

                            • start_response -- The WSGI start_response function.

                     This function returns the HTTP response body to deliver to the client as a byte sequence.

              leave_room(sid, room, namespace=None)
                     Leave a room.

                     This function removes the client from a room.

                     Parameterssid -- Session ID of the client.

                            • room -- Room name.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the default namespace is used.

              on(event, handler=None, namespace=None)
                     Register an event handler.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • handler  --  The  function  that  should be invoked to handle the event. When this
                              parameter is not given, the method acts as a decorator for the handler function.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the handler is associated with the default namespace.

                     Example usage:

                        # as a decorator:
                        @socket_io.on('connect', namespace='/chat')
                        def connect_handler(sid, environ):
                            print('Connection request')
                            if environ['REMOTE_ADDR'] in blacklisted:
                                return False  # reject

                        # as a method:
                        def message_handler(sid, msg):
                            print('Received message: ', msg)
                            eio.send(sid, 'response')
                        socket_io.on('message', namespace='/chat', message_handler)

                     The  handler  function  receives the sid (session ID) for the client as first argument. The
                     'connect' event handler receives the WSGI environment as a second argument, and can  return
                     False  to  reject the connection. The 'message' handler and handlers for custom event names
                     receive the message payload as a second argument.   Any  values  returned  from  a  message
                     handler  will be passed to the client's acknowledgement callback function if it exists. The
                     'disconnect' handler does not take a second argument.

              register_namespace(namespace_handler)
                     Register a namespace handler object.

                     Parameters
                            namespace_handler -- An instance of a Namespace subclass that handles all the  event
                            traffic for a namespace.

              rooms(sid, namespace=None)
                     Return the rooms a client is in.

                     Parameterssid -- Session ID of the client.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the default namespace is used.

              save_session(sid, session, namespace=None)
                     Store the user session for a client.

                     Parameterssid -- The session id of the client.

                            • session -- The session dictionary.

                            • namespace -- The Socket.IO namespace. If this  argument  is  omitted  the  default
                              namespace is used.

              send(data, to=None, room=None, skip_sid=None, namespace=None, callback=None, **kwargs)
                     Send a message to one or more connected clients.

                     This  function  emits  an  event  with the name 'message'. Use emit() to issue custom event
                     names.

                     Parametersdata -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • to  -- The recipient of the message. This can be set to the session ID of a client
                              to address only that client, or to to any custom room created by  the  application
                              to  address all the clients in that room, If this argument is omitted the event is
                              broadcasted to all connected clients.

                            • room -- Alias for the to parameter.

                            • skip_sid -- The session ID of a client to skip when broadcasting to a room  or  to
                              all  clients. This can be used to prevent a message from being sent to the sender.
                              To skip multiple sids, pass a list.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

                            • ignore_queue -- Only used when a message queue is configured. If set to True,  the
                              event  is  emitted to the clients directly, without going through the queue.  This
                              is more efficient, but only works when a single server  process  is  used.  It  is
                              recommended to always leave this parameter with its default value of False.

              session(sid, namespace=None)
                     Return the user session for a client with context manager syntax.

                     Parameters
                            sid -- The session id of the client.

                     This  is  a  context  manager  that returns the user session dictionary for the client. Any
                     changes that are made to this dictionary inside the context manager block are saved back to
                     the session. Example usage:

                        @sio.on('connect')
                        def on_connect(sid, environ):
                            username = authenticate_user(environ)
                            if not username:
                                return False
                            with sio.session(sid) as session:
                                session['username'] = username

                        @sio.on('message')
                        def on_message(sid, msg):
                            with sio.session(sid) as session:
                                print('received message from ', session['username'])

              sleep(seconds=0)
                     Sleep for the requested amount of time using the appropriate async model.

                     This  is a utility function that applications can use to put a task to sleep without having
                     to worry about using the correct call for the selected async mode.

              start_background_task(target, *args, **kwargs)
                     Start a background task using the appropriate async model.

                     This is a utility function that applications can use to start a background task  using  the
                     method that is compatible with the selected async mode.

                     Parameterstarget -- the target function to execute.

                            • args -- arguments to pass to the function.

                            • kwargs -- keyword arguments to pass to the function.

                     This  function  returns  an  object compatible with the Thread class in the Python standard
                     library. The start() method on this object is already called by this function.

              transport(sid)
                     Return the name of the transport used by the client.

                     The two possible values returned by this function are 'polling' and 'websocket'.

                     Parameters
                            sid -- The session of the client.

   AsyncServer class
       class socketio.AsyncServer(client_manager=None, logger=False, json=None, async_handlers=True, **kwargs)
              A Socket.IO server for asyncio.

              This class implements a fully compliant Socket.IO  web  server  with  support  for  websocket  and
              long-polling transports, compatible with the asyncio framework on Python 3.5 or newer.

              Parametersclient_manager -- The client manager instance that will manage the client list. When this
                       is omitted, the client list is stored in an in-memory structure, so the use  of  multiple
                       connected servers is not possible.

                     • logger  --  To  enable  logging  set  to  True or pass a logger object to use. To disable
                       logging set to False.

                     • json -- An alternative json module to use for encoding and decoding packets. Custom  json
                       modules must have dumps and loads functions that are compatible with the standard library
                       versions.

                     • async_handlers -- If set to True, event handlers are executed in separate threads. To run
                       handlers synchronously, set to False. The default is True.

                     • kwargs -- Connection parameters for the underlying Engine.IO server.

              The Engine.IO configuration supports the following settings:

              Parametersasync_mode  --  The  asynchronous  model  to  use.  See  the  Deployment  section  in the
                       documentation for  a  description  of  the  available  options.  Valid  async  modes  are
                       "aiohttp".  If this argument is not given, an async mode is chosen based on the installed
                       packages.

                     • ping_timeout -- The time in seconds that the client  waits  for  the  server  to  respond
                       before disconnecting.

                     • ping_interval -- The interval in seconds at which the client pings the server.

                     • max_http_buffer_size -- The maximum size of a message when using the polling transport.

                     • allow_upgrades -- Whether to allow transport upgrades or not.

                     • http_compression -- Whether to compress packages when using the polling transport.

                     • compression_threshold -- Only compress messages when their byte size is greater than this
                       value.

                     • cookie -- Name of the HTTP cookie that contains the client session id. If set to None,  a
                       cookie is not sent to the client.

                     • cors_allowed_origins  --  Origin  or  list of origins that are allowed to connect to this
                       server. Only the same origin is allowed by default. Set this argument to '*' to allow all
                       origins, or to [] to disable CORS handling.

                     • cors_credentials -- Whether credentials (cookies, authentication) are allowed in requests
                       to this server.

                     • monitor_clients -- If set to True, a background task will  ensure  inactive  clients  are
                       closed.  Set  to  False  to disable the monitoring task (not recommended). The default is
                       True.

                     • engineio_logger -- To enable Engine.IO logging set to True or pass  a  logger  object  to
                       use. To disable logging set to False.

              attach(app, socketio_path='socket.io')
                     Attach the Socket.IO server to an application.

              call(event, data=None, to=None, sid=None, namespace=None, timeout=60, **kwargs)
                     Emit a custom event to a client and wait for the response.

                     Parametersevent  --  The  event  name.  It  can  be  any  string. The event names 'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • to -- The session ID of the recipient client.

                            • sid -- Alias for the to parameter.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the event is emitted to the default namespace.

                            • timeout -- The waiting timeout. If  the  timeout  is  reached  before  the  client
                              acknowledges the event, then a TimeoutError exception is raised.

                            • ignore_queue  -- Only used when a message queue is configured. If set to True, the
                              event is emitted to the client directly, without going through the queue.  This is
                              more  efficient,  but  only  works  when  a  single  server process is used. It is
                              recommended to always leave this parameter with its default value of False.

              close_room(room, namespace=None)
                     Close a room.

                     This function removes all the clients from the given room.

                     Parametersroom -- Room name.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the default namespace is used.

                     Note: this method is a coroutine.

              disconnect(sid, namespace=None)
                     Disconnect a client.

                     Parameterssid -- Session ID of the client.

                            • namespace  --  The  Socket.IO namespace to disconnect. If this argument is omitted
                              the default namespace is used.

                     Note: this method is a coroutine.

              emit(event, data=None, to=None, room=None, skip_sid=None, namespace=None, callback=None, **kwargs)
                     Emit a custom event to one or more connected clients.

                     Parametersevent -- The event name.  It  can  be  any  string.  The  event  names  'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • data -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • to -- The recipient of the message. This can be set to the session ID of a  client
                              to  address  only that client, or to to any custom room created by the application
                              to address all the clients in that room, If this argument is omitted the event  is
                              broadcasted to all connected clients.

                            • room -- Alias for the to parameter.

                            • skip_sid  --  The session ID of a client to skip when broadcasting to a room or to
                              all clients. This can be used to prevent a message from being sent to the sender.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

                            • ignore_queue -- Only used when a message queue is configured. If set to True,  the
                              event  is  emitted to the clients directly, without going through the queue.  This
                              is more efficient, but only works when a single server  process  is  used.  It  is
                              recommended to always leave this parameter with its default value of False.

                     Note: this method is a coroutine.

              enter_room(sid, room, namespace=None)
                     Enter a room.

                     This  function  adds  the  client to a room. The emit() and send() functions can optionally
                     broadcast events to all the clients in a room.

                     Parameterssid -- Session ID of the client.

                            • room -- Room name. If the room does not exist it is created.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the default namespace is used.

              event(*args, **kwargs)
                     Decorator to register an event handler.

                     This  is  a  simplified  version  of  the  on()  method  that takes the event name from the
                     decorated function.

                     Example usage:

                        @sio.event
                        def my_event(data):
                            print('Received data: ', data)

                     The above example is equivalent to:

                        @sio.on('my_event')
                        def my_event(data):
                            print('Received data: ', data)

                     A custom namespace can be given as an argument to the decorator:

                        @sio.event(namespace='/test')
                        def my_event(data):
                            print('Received data: ', data)

              get_session(sid, namespace=None)
                     Return the user session for a client.

                     Parameterssid -- The session id of the client.

                            • namespace -- The Socket.IO namespace. If this  argument  is  omitted  the  default
                              namespace is used.

                     The  return value is a dictionary. Modifications made to this dictionary are not guaranteed
                     to be preserved. If you want to modify the user session, use the  session  context  manager
                     instead.

              handle_request(*args, **kwargs)
                     Handle an HTTP request from the client.

                     This  is  the  entry  point  of  the  Socket.IO application. This function returns the HTTP
                     response body to deliver to the client.

                     Note: this method is a coroutine.

              leave_room(sid, room, namespace=None)
                     Leave a room.

                     This function removes the client from a room.

                     Parameterssid -- Session ID of the client.

                            • room -- Room name.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the default namespace is used.

              on(event, handler=None, namespace=None)
                     Register an event handler.

                     Parametersevent  --  The  event  name.  It  can  be  any  string. The event names 'connect',
                              'message' and 'disconnect' are reserved and should not be used.

                            • handler -- The function that should be invoked to  handle  the  event.  When  this
                              parameter is not given, the method acts as a decorator for the handler function.

                            • namespace  --  The  Socket.IO namespace for the event. If this argument is omitted
                              the handler is associated with the default namespace.

                     Example usage:

                        # as a decorator:
                        @socket_io.on('connect', namespace='/chat')
                        def connect_handler(sid, environ):
                            print('Connection request')
                            if environ['REMOTE_ADDR'] in blacklisted:
                                return False  # reject

                        # as a method:
                        def message_handler(sid, msg):
                            print('Received message: ', msg)
                            eio.send(sid, 'response')
                        socket_io.on('message', namespace='/chat', message_handler)

                     The handler function receives the sid (session ID) for the client as  first  argument.  The
                     'connect'  event handler receives the WSGI environment as a second argument, and can return
                     False to reject the connection. The 'message' handler and handlers for custom  event  names
                     receive  the  message  payload  as  a  second argument.  Any values returned from a message
                     handler will be passed to the client's acknowledgement callback function if it exists.  The
                     'disconnect' handler does not take a second argument.

              register_namespace(namespace_handler)
                     Register a namespace handler object.

                     Parameters
                            namespace_handler  -- An instance of a Namespace subclass that handles all the event
                            traffic for a namespace.

              rooms(sid, namespace=None)
                     Return the rooms a client is in.

                     Parameterssid -- Session ID of the client.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the default namespace is used.

              save_session(sid, session, namespace=None)
                     Store the user session for a client.

                     Parameterssid -- The session id of the client.

                            • session -- The session dictionary.

                            • namespace  --  The  Socket.IO  namespace.  If this argument is omitted the default
                              namespace is used.

              send(data, to=None, room=None, skip_sid=None, namespace=None, callback=None, **kwargs)
                     Send a message to one or more connected clients.

                     This function emits an event with the name 'message'. Use  emit()  to  issue  custom  event
                     names.

                     Parametersdata -- The data to send to the client or clients. Data can be of type str, bytes,
                              list or dict. If a list or dict, the data will be serialized as JSON.

                            • to -- The recipient of the message. This can be set to the session ID of a  client
                              to  address  only that client, or to to any custom room created by the application
                              to address all the clients in that room, If this argument is omitted the event  is
                              broadcasted to all connected clients.

                            • room -- Alias for the to parameter.

                            • skip_sid  --  The session ID of a client to skip when broadcasting to a room or to
                              all clients. This can be used to prevent a message from being sent to the sender.

                            • namespace -- The Socket.IO namespace for the event. If this  argument  is  omitted
                              the event is emitted to the default namespace.

                            • callback  --  If given, this function will be called to acknowledge the the client
                              has received the message. The arguments that will be passed to  the  function  are
                              those  provided by the client. Callback functions can only be used when addressing
                              an individual client.

                            • ignore_queue -- Only used when a message queue is configured. If set to True,  the
                              event  is  emitted to the clients directly, without going through the queue.  This
                              is more efficient, but only works when a single server  process  is  used.  It  is
                              recommended to always leave this parameter with its default value of False.

                     Note: this method is a coroutine.

              session(sid, namespace=None)
                     Return the user session for a client with context manager syntax.

                     Parameters
                            sid -- The session id of the client.

                     This  is  a  context  manager  that returns the user session dictionary for the client. Any
                     changes that are made to this dictionary inside the context manager block are saved back to
                     the session. Example usage:

                        @eio.on('connect')
                        def on_connect(sid, environ):
                            username = authenticate_user(environ)
                            if not username:
                                return False
                            with eio.session(sid) as session:
                                session['username'] = username

                        @eio.on('message')
                        def on_message(sid, msg):
                            async with eio.session(sid) as session:
                                print('received message from ', session['username'])

              sleep(seconds=0)
                     Sleep for the requested amount of time using the appropriate async model.

                     This  is a utility function that applications can use to put a task to sleep without having
                     to worry about using the correct call for the selected async mode.

                     Note: this method is a coroutine.

              start_background_task(target, *args, **kwargs)
                     Start a background task using the appropriate async model.

                     This is a utility function that applications can use to start a background task  using  the
                     method that is compatible with the selected async mode.

                     Parameterstarget -- the target function to execute. Must be a coroutine.

                            • args -- arguments to pass to the function.

                            • kwargs -- keyword arguments to pass to the function.

                     The return value is a asyncio.Task object.

                     Note: this method is a coroutine.

              transport(sid)
                     Return the name of the transport used by the client.

                     The two possible values returned by this function are 'polling' and 'websocket'.

                     Parameters
                            sid -- The session of the client.

   ConnectionRefusedError class
   WSGIApp class
       class socketio.WSGIApp(socketio_app, wsgi_app=None, static_files=None, socketio_path='socket.io')
              WSGI middleware for Socket.IO.

              This  middleware dispatches traffic to a Socket.IO application. It can also serve a list of static
              files to the client, or forward unrelated HTTP traffic to another WSGI application.

              Parameterssocketio_app -- The Socket.IO server. Must be an instance of the socketio.Server class.

                     • wsgi_app -- The WSGI app that receives all other traffic.

                     • static_files -- A dictionary with static file mapping rules. See  the  documentation  for
                       details on this argument.

                     • socketio_path  --  The  endpoint where the Socket.IO application should be installed. The
                       default value is appropriate for most cases.

              Example usage:

                 import socketio
                 import eventlet
                 from . import wsgi_app

                 sio = socketio.Server()
                 app = socketio.WSGIApp(sio, wsgi_app)
                 eventlet.wsgi.server(eventlet.listen(('', 8000)), app)

   ASGIApp class
       class         socketio.ASGIApp(socketio_server,          other_asgi_app=None,          static_files=None,
       socketio_path='socket.io')
              ASGI application middleware for Socket.IO.

              This middleware dispatches traffic to an Socket.IO application. It can also serve a list of static
              files to the client, or forward unrelated HTTP traffic to another ASGI application.

              Parameterssocketio_server -- The Socket.IO server. Must be an instance of the  socketio.AsyncServer
                       class.

                     • static_files  --  A  dictionary with static file mapping rules. See the documentation for
                       details on this argument.

                     • other_asgi_app -- A separate ASGI app that receives all other traffic.

                     • socketio_path -- The endpoint where the Socket.IO application should  be  installed.  The
                       default value is appropriate for most cases.

              Example usage:

                 import socketio
                 import uvicorn

                 sio = socketio.AsyncServer()
                 app = engineio.ASGIApp(sio, static_files={
                     '/': 'index.html',
                     '/static': './public',
                 })
                 uvicorn.run(app, host='127.0.0.1', port=5000)

   Middleware class (deprecated)
       class socketio.Middleware(socketio_app, wsgi_app=None, socketio_path='socket.io')
              This class has been renamed to WSGIApp and is now deprecated.

   ClientNamespace class
       class socketio.ClientNamespace(namespace=None)
              Base class for client-side class-based namespaces.

              A class-based namespace is a class that contains all the event handlers for a Socket.IO namespace.
              The  event  handlers  are  methods  of  the  class  with  the  prefix  on_,  such  as  on_connect,
              on_disconnect, on_message, on_json, and so on.

              Parameters
                     namespace -- The Socket.IO namespace to be used with all the event handlers defined in this
                     class. If this argument is omitted, the default namespace is used.

              disconnect()
                     Disconnect from the server.

                     The only difference with the socketio.Client.disconnect() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              emit(event, data=None, namespace=None, callback=None)
                     Emit a custom event to the server.

                     The  only  difference  with  the  socketio.Client.emit()  method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              send(data, room=None, skip_sid=None, namespace=None, callback=None)
                     Send a message to the server.

                     The only difference with the socketio.Client.send()  method  is  that  when  the  namespace
                     argument is not given the namespace associated with the class is used.

              trigger_event(event, *args)
                     Dispatch an event to the proper handler method.

                     In  the  most common usage, this method is not overloaded by subclasses, as it performs the
                     routing of events to methods. However, this method can be overridden if special dispatching
                     rules are needed, or if having a single method that catches all events is desired.

   Namespace class
       class socketio.Namespace(namespace=None)
              Base class for server-side class-based namespaces.

              A class-based namespace is a class that contains all the event handlers for a Socket.IO namespace.
              The  event  handlers  are  methods  of  the  class  with  the  prefix  on_,  such  as  on_connect,
              on_disconnect, on_message, on_json, and so on.

              Parameters
                     namespace -- The Socket.IO namespace to be used with all the event handlers defined in this
                     class. If this argument is omitted, the default namespace is used.

              close_room(room, namespace=None)
                     Close a room.

                     The only difference with the socketio.Server.close_room() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              disconnect(sid, namespace=None)
                     Disconnect a client.

                     The only difference with the socketio.Server.disconnect() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              emit(event, data=None, room=None, skip_sid=None, namespace=None, callback=None)
                     Emit a custom event to one or more connected clients.

                     The only difference with the socketio.Server.emit()  method  is  that  when  the  namespace
                     argument is not given the namespace associated with the class is used.

              enter_room(sid, room, namespace=None)
                     Enter a room.

                     The only difference with the socketio.Server.enter_room() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              get_session(sid, namespace=None)
                     Return the user session for a client.

                     The only  difference  with  the  socketio.Server.get_session()  method  is  that  when  the
                     namespace argument is not given the namespace associated with the class is used.

              leave_room(sid, room, namespace=None)
                     Leave a room.

                     The only difference with the socketio.Server.leave_room() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              rooms(sid, namespace=None)
                     Return the rooms a client is in.

                     The only difference with the socketio.Server.rooms() method  is  that  when  the  namespace
                     argument is not given the namespace associated with the class is used.

              save_session(sid, session, namespace=None)
                     Store the user session for a client.

                     The  only  difference  with  the  socketio.Server.save_session()  method  is  that when the
                     namespace argument is not given the namespace associated with the class is used.

              send(data, room=None, skip_sid=None, namespace=None, callback=None)
                     Send a message to one or more connected clients.

                     The only difference with the socketio.Server.send()  method  is  that  when  the  namespace
                     argument is not given the namespace associated with the class is used.

              session(sid, namespace=None)
                     Return the user session for a client with context manager syntax.

                     The  only  difference  with the socketio.Server.session() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              trigger_event(event, *args)
                     Dispatch an event to the proper handler method.

                     In the most common usage, this method is not overloaded by subclasses, as it  performs  the
                     routing of events to methods. However, this method can be overridden if special dispatching
                     rules are needed, or if having a single method that catches all events is desired.

   AsyncClientNamespace class
       class socketio.AsyncClientNamespace(namespace=None)
              Base class for asyncio client-side class-based namespaces.

              A class-based namespace is a class that contains all the event handlers for a Socket.IO namespace.
              The  event  handlers  are  methods  of  the  class  with  the  prefix  on_,  such  as  on_connect,
              on_disconnect, on_message, on_json, and so on. These can be regular functions or coroutines.

              Parameters
                     namespace -- The Socket.IO namespace to be used with all the event handlers defined in this
                     class. If this argument is omitted, the default namespace is used.

              disconnect()
                     Disconnect a client.

                     The only difference with the socketio.Client.disconnect() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              emit(event, data=None, namespace=None, callback=None)
                     Emit a custom event to the server.

                     The only difference with the socketio.Client.emit()  method  is  that  when  the  namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              send(data, namespace=None, callback=None)
                     Send a message to the server.

                     The  only  difference  with  the  socketio.Client.send()  method is that when the namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              trigger_event(event, *args)
                     Dispatch an event to the proper handler method.

                     In the most common usage, this method is not overloaded by subclasses, as it  performs  the
                     routing of events to methods. However, this method can be overridden if special dispatching
                     rules are needed, or if having a single method that catches all events is desired.

                     Note: this method is a coroutine.

   AsyncNamespace class
       class socketio.AsyncNamespace(namespace=None)
              Base class for asyncio server-side class-based namespaces.

              A class-based namespace is a class that contains all the event handlers for a Socket.IO namespace.
              The  event  handlers  are  methods  of  the  class  with  the  prefix  on_,  such  as  on_connect,
              on_disconnect, on_message, on_json, and so on. These can be regular functions or coroutines.

              Parameters
                     namespace -- The Socket.IO namespace to be used with all the event handlers defined in this
                     class. If this argument is omitted, the default namespace is used.

              close_room(room, namespace=None)
                     Close a room.

                     The only difference with the socketio.Server.close_room() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              disconnect(sid, namespace=None)
                     Disconnect a client.

                     The only difference with the socketio.Server.disconnect() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              emit(event, data=None, room=None, skip_sid=None, namespace=None, callback=None)
                     Emit a custom event to one or more connected clients.

                     The  only  difference  with  the  socketio.Server.emit()  method is that when the namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              enter_room(sid, room, namespace=None)
                     Enter a room.

                     The only difference with the socketio.Server.enter_room() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              get_session(sid, namespace=None)
                     Return the user session for a client.

                     The  only  difference  with  the  socketio.Server.get_session()  method  is  that  when the
                     namespace argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              leave_room(sid, room, namespace=None)
                     Leave a room.

                     The only difference with the socketio.Server.leave_room() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              rooms(sid, namespace=None)
                     Return the rooms a client is in.

                     The  only  difference  with  the  socketio.Server.rooms() method is that when the namespace
                     argument is not given the namespace associated with the class is used.

              save_session(sid, session, namespace=None)
                     Store the user session for a client.

                     The only difference  with  the  socketio.Server.save_session()  method  is  that  when  the
                     namespace argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              send(data, room=None, skip_sid=None, namespace=None, callback=None)
                     Send a message to one or more connected clients.

                     The  only  difference  with  the  socketio.Server.send()  method is that when the namespace
                     argument is not given the namespace associated with the class is used.

                     Note: this method is a coroutine.

              session(sid, namespace=None)
                     Return the user session for a client with context manager syntax.

                     The only difference with the socketio.Server.session() method is that  when  the  namespace
                     argument is not given the namespace associated with the class is used.

              trigger_event(event, *args)
                     Dispatch an event to the proper handler method.

                     In  the  most common usage, this method is not overloaded by subclasses, as it performs the
                     routing of events to methods. However, this method can be overridden if special dispatching
                     rules are needed, or if having a single method that catches all events is desired.

                     Note: this method is a coroutine.

   BaseManager class
       class socketio.BaseManager
              Manage client connections.

              This  class  keeps track of all the clients and the rooms they are in, to support the broadcasting
              of messages. The data used by this class is stored in a memory structure,  making  it  appropriate
              only  for  single  process  services.  More  sophisticated  storage backends can be implemented by
              subclasses.

              close_room(room, namespace)
                     Remove all participants from a room.

              connect(sid, namespace)
                     Register a client connection to a namespace.

              disconnect(sid, namespace)
                     Register a client disconnect from a namespace.

              emit(event, data, namespace, room=None, skip_sid=None, callback=None, **kwargs)
                     Emit a message to a single client, a room, or all the clients connected to the namespace.

              enter_room(sid, namespace, room)
                     Add a client to a room.

              get_namespaces()
                     Return an iterable with the active namespace names.

              get_participants(namespace, room)
                     Return an iterable with the active participants in a room.

              get_rooms(sid, namespace)
                     Return the rooms a client is in.

              initialize()
                     Invoked before the first request is received. Subclasses can add their initialization  code
                     here.

              leave_room(sid, namespace, room)
                     Remove a client from a room.

              pre_disconnect(sid, namespace)
                     Put the client in the to-be-disconnected list.

                     This  allows  the  client  data  structures  to  be present while the disconnect handler is
                     invoked, but still recognize the fact that the client is soon going away.

              trigger_callback(sid, namespace, id, data)
                     Invoke an application callback.

   PubSubManager class
       class socketio.PubSubManager(channel='socketio', write_only=False, logger=None)
              Manage a client list attached to a pub/sub backend.

              This is a base class that enables multiple servers to share the list of clients, with the  servers
              communicating  events  through  a  pub/sub  backend.  The use of a pub/sub backend also allows any
              client connected to the backend to emit events addressed to Socket.IO clients.

              The actual backends must be implemented by subclasses, this class only provides a pub/sub  generic
              framework.

              Parameters
                     channel -- The channel name on which the server sends and receives notifications.

              close_room(room, namespace=None)
                     Remove all participants from a room.

              emit(event, data, namespace=None, room=None, skip_sid=None, callback=None, **kwargs)
                     Emit a message to a single client, a room, or all the clients connected to the namespace.

                     This  method  takes  care  or propagating the message to all the servers that are connected
                     through the message queue.

                     The parameters are the same as in Server.emit().

              initialize()
                     Invoked before the first request is received. Subclasses can add their initialization  code
                     here.

   KombuManager class
       class         socketio.KombuManager(url='amqp://guest:guest@localhost:5672//',        channel='socketio',
       write_only=False,  logger=None,   connection_options=None,   exchange_options=None,   queue_options=None,
       producer_options=None)
              Client manager that uses kombu for inter-process messaging.

              This  class implements a client manager backend for event sharing across multiple processes, using
              RabbitMQ, Redis or any other messaging mechanism supported by kombu.

              To use a kombu backend, initialize the Server instance as follows:

                 url = 'amqp://user:password@hostname:port//'
                 server = socketio.Server(client_manager=socketio.KombuManager(url))

              Parametersurl -- The connection URL for the backend messaging queue. Example  connection  URLs  are
                       'amqp://guest:guest@localhost:5672//'  and  'redis://localhost:6379/'  for  RabbitMQ  and
                       Redis respectively. Consult  the  kombu  documentation  for  more  on  how  to  construct
                       connection URLs.

                     • channel -- The channel name on which the server sends and receives notifications. Must be
                       the same in all the servers.

                     • write_only -- If set to True, only initialize  to  emit  events.  The  default  of  False
                       initializes the class for emitting and receiving.

                     • connection_options -- additional keyword arguments to be passed to kombu.Connection().

                     • exchange_options -- additional keyword arguments to be passed to kombu.Exchange().

                     • queue_options -- additional keyword arguments to be passed to kombu.Queue().

                     • producer_options -- additional keyword arguments to be passed to kombu.Producer().

              initialize()
                     Invoked  before the first request is received. Subclasses can add their initialization code
                     here.

   RedisManager class
       class   socketio.RedisManager(url='redis://localhost:6379/0',    channel='socketio',    write_only=False,
       logger=None, redis_options=None)
              Redis based client manager.

              This  class implements a Redis backend for event sharing across multiple processes. Only kept here
              as one more example of how to build a  custom  backend,  since  the  kombu  backend  is  perfectly
              adequate to support a Redis message queue.

              To use a Redis backend, initialize the Server instance as follows:

                 url = 'redis://hostname:port/0'
                 server = socketio.Server(client_manager=socketio.RedisManager(url))

              Parametersurl  -- The connection URL for the Redis server. For a default Redis store running on the
                       same host, use redis://.

                     • channel -- The channel name on which the server sends and receives notifications. Must be
                       the same in all the servers.

                     • write_only  --  If  set  to  True,  only  initialize to emit events. The default of False
                       initializes the class for emitting and receiving.

                     • redis_options -- additional keyword arguments to be passed to Redis.from_url().

              initialize()
                     Invoked before the first request is received. Subclasses can add their initialization  code
                     here.

   KafkaManager class
       class socketio.KafkaManager(url='kafka://localhost:9092', channel='socketio', write_only=False)
              Kafka based client manager.

              This class implements a Kafka backend for event sharing across multiple processes.

              To use a Kafka backend, initialize the Server instance as follows:

                 url = 'kafka://hostname:port'
                 server = socketio.Server(client_manager=socketio.KafkaManager(url))

              Parametersurl  -- The connection URL for the Kafka server. For a default Kafka store running on the
                       same host, use kafka://.

                     • channel -- The channel name (topic) on which the server sends and receives notifications.
                       Must be the same in all the servers.

                     • write_only  --  If  set  to  True,  only  initialize to emit events. The default of False
                       initializes the class for emitting and receiving.

   AsyncManager class
       class socketio.AsyncManager
              Manage a client list for an asyncio server.

              close_room(room, namespace)
                     Remove all participants from a room.

                     Note: this method is a coroutine.

              connect(sid, namespace)
                     Register a client connection to a namespace.

              disconnect(sid, namespace)
                     Register a client disconnect from a namespace.

              emit(event, data, namespace, room=None, skip_sid=None, callback=None, **kwargs)
                     Emit a message to a single client, a room, or all the clients connected to the namespace.

                     Note: this method is a coroutine.

              enter_room(sid, namespace, room)
                     Add a client to a room.

              get_namespaces()
                     Return an iterable with the active namespace names.

              get_participants(namespace, room)
                     Return an iterable with the active participants in a room.

              get_rooms(sid, namespace)
                     Return the rooms a client is in.

              initialize()
                     Invoked before the first request is received. Subclasses can add their initialization  code
                     here.

              leave_room(sid, namespace, room)
                     Remove a client from a room.

              pre_disconnect(sid, namespace)
                     Put the client in the to-be-disconnected list.

                     This  allows  the  client  data  structures  to  be present while the disconnect handler is
                     invoked, but still recognize the fact that the client is soon going away.

              trigger_callback(sid, namespace, id, data)
                     Invoke an application callback.

                     Note: this method is a coroutine.

   AsyncRedisManager class
       class  socketio.AsyncRedisManager(url='redis://localhost:6379/0',  channel='socketio',  write_only=False,
       logger=None)
              Redis based client manager for asyncio servers.

              This  class implements a Redis backend for event sharing across multiple processes. Only kept here
              as one more example of how to build a  custom  backend,  since  the  kombu  backend  is  perfectly
              adequate to support a Redis message queue.

              To use a Redis backend, initialize the Server instance as follows:

                 server = socketio.Server(client_manager=socketio.AsyncRedisManager(
                     'redis://hostname:port/0'))

              Parametersurl  -- The connection URL for the Redis server. For a default Redis store running on the
                       same host, use redis://.  To use an SSL connection, use rediss://.

                     • channel -- The channel name on which the server sends and receives notifications. Must be
                       the same in all the servers.

                     • write_only  --  If  set  to  True,  only  initialize to emit events. The default of False
                       initializes the class for emitting and receiving.

   AsyncAioPikaManager class
       class     socketio.AsyncAioPikaManager(url='amqp://guest:guest@localhost:5672//',     channel='socketio',
       write_only=False, logger=None)
              Client manager that uses aio_pika for inter-process messaging under asyncio.

              This  class implements a client manager backend for event sharing across multiple processes, using
              RabbitMQ

              To use a aio_pika backend, initialize the Server instance as follows:

                 url = 'amqp://user:password@hostname:port//'
                 server = socketio.Server(client_manager=socketio.AsyncAioPikaManager(
                     url))

              Parametersurl -- The connection URL for the backend messaging queue. Example  connection  URLs  are
                       'amqp://guest:guest@localhost:5672//' for RabbitMQ.

                     • channel -- The channel name on which the server sends and receives notifications. Must be
                       the same in all the servers.  With this manager, the channel name is the exchange name in
                       rabbitmq

                     • write_only  --  If  set  to  True,  only  initialize to emit events. The default of False
                       initializes the class for emitting and receiving.

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AUTHOR

       Miguel Grinberg

COPYRIGHT

       2018, Miguel Grinberg

                                                  Dec 27, 2019                                PYTHON-SOCKETIO(1)