WebSocket

HTML5 与 WebSocket

WebSocket协议在2011年被标准化, 最初的目标是让浏览器与服务器建立稳定的双向连接. 在此之前, 浏览器曾只支持HTTPRequests, 并不适合双向通信.

这个协议相当简单, 基于消息, 是一个非常强大的向浏览器推送通知的工具, 已经被用来实现聊天, 回合制游戏等. 它仍使用TCP连接, 这对可靠性有好处, 但对延迟没有好处, 所以不适合实时的应用, 比如VoIP和快节奏的游戏(这些用例见 WebRTC).

由于它的简单性, 广泛的兼容性以及比原始TCP连接更容易使用,WebSocket很快就开始在浏览器以外的地方应用, 在本地应用程序中作为与网络服务器通信的一种手段.

Godot在本机和HTML5导出中都支持WebSocket.

在Godot中使用WebSocket

在Godot中,WebSocket通过三个主要类来实现 WebSocketClient, WebSocketServer, 和 WebSocketPeer.WebSocket的实现与高级多人游戏兼容. 更多细节请参见 high-level multiplayer 一节.

警告

当导出到 Android 时，在导出项目或使用一键部署之前，确保在 Android 导出预设中启用 [code]INTERNET[/code] 权限。否则，任何形式的网络通信都会被 Android 系统阻止。

最小客户端示例

本示例将向您展示如何创建与远程服务器的 WebSocket 连接, 以及如何发送和接收数据.

  1. extends Node
  3. # The URL we will connect to
  4. export var websocket_url = "ws://echo.websocket.org"
  6. # Our WebSocketClient instance
  7. var _client = WebSocketClient.new()
  9. func _ready():
  10.     # Connect base signals to get notified of connection open, close, and errors.
  11.     _client.connect("connection_closed", self, "_closed")
  12.     _client.connect("connection_error", self, "_closed")
  13.     _client.connect("connection_established", self, "_connected")
  14.     # This signal is emitted when not using the Multiplayer API every time
  15.     # a full packet is received.
  16.     # Alternatively, you could check get_peer(1).get_available_packets() in a loop.
  17.     _client.connect("data_received", self, "_on_data")
  19.     # Initiate connection to the given URL.
  20.     var err = _client.connect_to_url(websocket_url)
  21.     if err != OK:
  22.         print("Unable to connect")
  23.         set_process(false)
  25. func _closed(was_clean = false):
  26.     # was_clean will tell you if the disconnection was correctly notified
  27.     # by the remote peer before closing the socket.
  28.     print("Closed, clean: ", was_clean)
  29.     set_process(false)
  31. func _connected(proto = ""):
  32.     # This is called on connection, "proto" will be the selected WebSocket
  33.     # sub-protocol (which is optional)
  34.     print("Connected with protocol: ", proto)
  35.     # You MUST always use get_peer(1).put_packet to send data to server,
  36.     # and not put_packet directly when not using the MultiplayerAPI.
  37.     _client.get_peer(1).put_packet("Test packet".to_utf8())
  39. func _on_data():
  40.     # Print the received packet, you MUST always use get_peer(1).get_packet
  41.     # to receive data from server, and not get_packet directly when not
  42.     # using the MultiplayerAPI.
  43.     print("Got data from server: ", _client.get_peer(1).get_packet().get_string_from_utf8())
  45. func _process(delta):
  46.     # Call this in _process or _physics_process. Data transfer, and signals
  47.     # emission will only happen when calling this function.
  48.     _client.poll()

这将打印:

  1. Connected with protocol:
  2. Got data from server: Test packet

最小服务器示例

这个例子将告诉你如何创建一个监听远程连接的WebSocket服务器，以及如何发送和接收数据。

  1. extends Node
  3. # The port we will listen to
  4. const PORT = 9080
  5. # Our WebSocketServer instance
  6. var _server = WebSocketServer.new()
  8. func _ready():
  9.     # Connect base signals to get notified of new client connections,
  10.     # disconnections, and disconnect requests.
  11.     _server.connect("client_connected", self, "_connected")
  12.     _server.connect("client_disconnected", self, "_disconnected")
  13.     _server.connect("client_close_request", self, "_close_request")
  14.     # This signal is emitted when not using the Multiplayer API every time a
  15.     # full packet is received.
  16.     # Alternatively, you could check get_peer(PEER_ID).get_available_packets()
  17.     # in a loop for each connected peer.
  18.     _server.connect("data_received", self, "_on_data")
  19.     # Start listening on the given port.
  20.     var err = _server.listen(PORT)
  21.     if err != OK:
  22.         print("Unable to start server")
  23.         set_process(false)
  25. func _connected(id, proto):
  26.     # This is called when a new peer connects, "id" will be the assigned peer id,
  27.     # "proto" will be the selected WebSocket sub-protocol (which is optional)
  28.     print("Client %d connected with protocol: %s" % [id, proto])
  30. func _close_request(id, code, reason):
  31.     # This is called when a client notifies that it wishes to close the connection,
  32.     # providing a reason string and close code.
  33.     print("Client %d disconnecting with code: %d, reason: %s" % [id, code, reason])
  35. func _disconnected(id, was_clean = false):
  36.     # This is called when a client disconnects, "id" will be the one of the
  37.     # disconnecting client, "was_clean" will tell you if the disconnection
  38.     # was correctly notified by the remote peer before closing the socket.
  39.     print("Client %d disconnected, clean: %s" % [id, str(was_clean)])
  41. func _on_data(id):
  42.     # Print the received packet, you MUST always use get_peer(id).get_packet to receive data,
  43.     # and not get_packet directly when not using the MultiplayerAPI.
  44.     var pkt = _server.get_peer(id).get_packet()
  45.     print("Got data from client %d: %s ... echoing" % [id, pkt.get_string_from_utf8()])
  46.     _server.get_peer(id).put_packet(pkt)
  48. func _process(delta):
  49.     # Call this in _process or _physics_process.
  50.     # Data transfer, and signals emission will only happen when calling this function.
  51.     _server.poll()

这将打印(当客户端连接时)与此类似的东西:

  1. Client 1348090059 connected with protocol: selected-protocol
  2. Got data from client 1348090059: Test packet ... echoing

高级聊天演示

在 godot demo projects 下 networking/websocket_chat 和 networking/websocket_multiplayer 有一个更高级的聊天演示demo, 可以选择使用多人中级抽象和高级多人演示demo.