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WebSocket

HTML5 與 WebSocket

WebSocket協定在2011年被標準化, 最初的目標是讓瀏覽器與伺服器建立穩定的雙向連接. 在此之前, 瀏覽器曾只支援HTTPRequests, 並不適合雙向通信.

這個協定相當簡單, 基於消息, 是一個非常強大的向瀏覽器推送通知的工具, 已經被用來實作聊天, 回合制遊戲等. 它仍使用TCP連接, 這對可靠性有好處, 但對延遲沒有好處, 所以不適合即時的應用, 比如VoIP和快節奏的遊戲(這些用例見 WebRTC).

由於它的簡單性, 廣泛的相容性以及比原始TCP連接更容易使用,WebSocket很快就開始在瀏覽器以外的地方應用, 在本地應用程式中作為與網路伺服器通信的一種手段.

Godot在本機和HTML5匯出中都支援WebSocket.

在 Godot 中使用 WebSocket

在Godot中,WebSocket通過三個主要類來實作 WebSocketClient, WebSocketServer, 和 WebSocketPeer.WebSocket的實作與高級多人遊戲相容. 更多細節請參見 high-level multiplayer 一節.

警告

當匯出到 Android 時，在匯出專案或使用一鍵部署之前，確保在 Android 匯出預設中啟用 INTERNET 許可權。否則，任何形式的網路通信都會被 Android 系統阻止。

最小使用者端範例

本範例將向您展示如何建立與遠端伺服器的 WebSocket 連接, 以及如何發送和接收資料.

extends Node

# The URL we will connect to
export var websocket_url = "wss://libwebsockets.org"

# Our WebSocketClient instance
var _client = WebSocketClient.new()

func _ready():
    # Connect base signals to get notified of connection open, close, and errors.
    _client.connection_closed.connect(_closed)
    _client.connection_error.connect(_closed)
    _client.connection_established.connect(_connected)
    # This signal is emitted when not using the Multiplayer API every time
    # a full packet is received.
    # Alternatively, you could check get_peer(1).get_available_packets() in a loop.
    _client.data_received.connect(_on_data)

    # Initiate connection to the given URL.
    var err = _client.connect_to_url(websocket_url, ["lws-mirror-protocol"])
    if err != OK:
        print("Unable to connect")
        set_process(false)

func _closed(was_clean = false):
    # was_clean will tell you if the disconnection was correctly notified
    # by the remote peer before closing the socket.
    print("Closed, clean: ", was_clean)
    set_process(false)

func _connected(proto = ""):
    # This is called on connection, "proto" will be the selected WebSocket
    # sub-protocol (which is optional)
    print("Connected with protocol: ", proto)
    # You MUST always use get_peer(1).put_packet to send data to server,
    # and not put_packet directly when not using the MultiplayerAPI.
    _client.get_peer(1).put_packet("Test packet".to_utf8())

func _on_data():
    # Print the received packet, you MUST always use get_peer(1).get_packet
    # to receive data from server, and not get_packet directly when not
    # using the MultiplayerAPI.
    print("Got data from server: ", _client.get_peer(1).get_packet().get_string_from_utf8())

func _process(delta):
    # Call this in _process or _physics_process. Data transfer, and signals
    # emission will only happen when calling this function.
    _client.poll()

這將列印:

Connected with protocol:
Got data from server: Test packet

最小伺服器範例

這個例子將告訴你如何建立一個監聽遠端連接的WebSocket伺服器，以及如何發送和接收資料。

extends Node

# The port we will listen to
const PORT = 9080
# Our WebSocketServer instance
var _server = WebSocketServer.new()

func _ready():
    # Connect base signals to get notified of new client connections,
    # disconnections, and disconnect requests.
    _server.client_connected.connect(_connected)
    _server.client_disconnected.connect(_disconnected)
    _server.client_close_request.connect(_close_request)
    # This signal is emitted when not using the Multiplayer API every time a
    # full packet is received.
    # Alternatively, you could check get_peer(PEER_ID).get_available_packets()
    # in a loop for each connected peer.
    _server.data_received.connect(_on_data)
    # Start listening on the given port.
    var err = _server.listen(PORT)
    if err != OK:
        print("Unable to start server")
        set_process(false)

func _connected(id, proto):
    # This is called when a new peer connects, "id" will be the assigned peer id,
    # "proto" will be the selected WebSocket sub-protocol (which is optional)
    print("Client %d connected with protocol: %s" % [id, proto])

func _close_request(id, code, reason):
    # This is called when a client notifies that it wishes to close the connection,
    # providing a reason string and close code.
    print("Client %d disconnecting with code: %d, reason: %s" % [id, code, reason])

func _disconnected(id, was_clean = false):
    # This is called when a client disconnects, "id" will be the one of the
    # disconnecting client, "was_clean" will tell you if the disconnection
    # was correctly notified by the remote peer before closing the socket.
    print("Client %d disconnected, clean: %s" % [id, str(was_clean)])

func _on_data(id):
    # Print the received packet, you MUST always use get_peer(id).get_packet to receive data,
    # and not get_packet directly when not using the MultiplayerAPI.
    var pkt = _server.get_peer(id).get_packet()
    print("Got data from client %d: %s ... echoing" % [id, pkt.get_string_from_utf8()])
    _server.get_peer(id).put_packet(pkt)

func _process(delta):
    # Call this in _process or _physics_process.
    # Data transfer, and signals emission will only happen when calling this function.
    _server.poll()

這將列印(當使用者端連接時)與此類似的東西:

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

高級聊天演示

在 godot demo projects 下 networking/websocket_chat 和 networking/websocket_multiplayer 有一個更高級的聊天演示demo, 可以選擇使用多人中級抽象和高級多人演示demo.