Using WebSockets
HTML5 and WebSocket
The WebSocket protocol was standardized in 2011 with the original goal of allowing browsers to create stable and bidirectional connections with a server. Before that, browsers used to only support HTTP requests, which aren't well-suited for bidirectional communication.
The protocol is message-based and a very powerful tool to send push notifications to browsers. It has been used to implement chats, turn-based games, and more. It still uses a TCP connection, which is good for reliability but not for latency, so it's not good for real-time applications like VoIP and fast-paced games (see WebRTC for those use cases).
Due to its simplicity, its wide compatibility, and being easier to use than a raw TCP connection, WebSocket started to spread outside the browsers, in native applications as a mean to communicate with network servers.
Godot supports WebSocket in both native and web exports.
Using WebSocket in Godot
WebSocket is implemented in Godot via WebSocketPeer. The WebSocket implementation is compatible with the High-Level Multiplayer. See section on High-level multiplayer for more details.
WARNING
When exporting to Android, make sure to enable the INTERNET permission in the Android export preset before exporting the project or using one-click deploy. Otherwise, network communication of any kind will be blocked by Android.
Minimal client example
This example will show you how to create a WebSocket connection to a remote server, and how to send and receive data.
extends Node
# The URL we will connect to.
# Use "ws://localhost:9080" if testing with the minimal server example below.
# `wss://` is used for secure connections,
# while `ws://` is used for plain text (insecure) connections.
@export var websocket_url = "wss://echo.websocket.org"
# Our WebSocketClient instance.
var socket = WebSocketPeer.new()
func _ready():
# Initiate connection to the given URL.
var err = socket.connect_to_url(websocket_url)
if err == OK:
print("Connecting to %s..." % websocket_url)
# Wait for the socket to connect.
await get_tree().create_timer(2).timeout
# Send data.
print("> Sending test packet.")
socket.send_text("Test packet")
else:
push_error("Unable to connect.")
set_process(false)
func _process(_delta):
# Call this in `_process()` or `_physics_process()`.
# Data transfer and state updates will only happen when calling this function.
socket.poll()
# get_ready_state() tells you what state the socket is in.
var state = socket.get_ready_state()
# `WebSocketPeer.STATE_OPEN` means the socket is connected and ready
# to send and receive data.
if state == WebSocketPeer.STATE_OPEN:
while socket.get_available_packet_count():
var packet = socket.get_packet()
if socket.was_string_packet():
var packet_text = packet.get_string_from_utf8()
print("< Got text data from server: %s" % packet_text)
else:
print("< Got binary data from server: %d bytes" % packet.size())
# `WebSocketPeer.STATE_CLOSING` means the socket is closing.
# It is important to keep polling for a clean close.
elif state == WebSocketPeer.STATE_CLOSING:
pass
# `WebSocketPeer.STATE_CLOSED` means the connection has fully closed.
# It is now safe to stop polling.
elif state == WebSocketPeer.STATE_CLOSED:
# The code will be `-1` if the disconnection was not properly notified by the remote peer.
var code = socket.get_close_code()
print("WebSocket closed with code: %d. Clean: %s" % [code, code != -1])
set_process(false) # Stop processing.This will print something similar to:
Connecting to wss://echo.websocket.org...
< Got text data from server: Request served by 7811941c69e658
> Sending test packet.
< Got text data from server: Test packetMinimal server example
This example will show you how to create a WebSocket server that listens for remote connections, and how to send and receive data.
extends Node
# The port we will listen to.
const PORT = 9080
# Our TCP Server instance.
var _tcp_server = TCPServer.new()
# Our connected peers list.
var _peers: Dictionary[int, WebSocketPeer] = {}
var last_peer_id := 1
func _ready():
# Start listening on the given port.
var err = _tcp_server.listen(PORT)
if err == OK:
print("Server started.")
else:
push_error("Unable to start server.")
set_process(false)
func _process(_delta):
while _tcp_server.is_connection_available():
last_peer_id += 1
print("+ Peer %d connected." % last_peer_id)
var ws = WebSocketPeer.new()
ws.accept_stream(_tcp_server.take_connection())
_peers[last_peer_id] = ws
# Iterate over all connected peers using "keys()" so we can erase in the loop
for peer_id in _peers.keys():
var peer = _peers[peer_id]
peer.poll()
var peer_state = peer.get_ready_state()
if peer_state == WebSocketPeer.STATE_OPEN:
while peer.get_available_packet_count():
var packet = peer.get_packet()
if peer.was_string_packet():
var packet_text = packet.get_string_from_utf8()
print("< Got text data from peer %d: %s ... echoing" % [peer_id, packet_text])
# Echo the packet back.
peer.send_text(packet_text)
else:
print("< Got binary data from peer %d: %d ... echoing" % [peer_id, packet.size()])
# Echo the packet back.
peer.send(packet)
elif peer_state == WebSocketPeer.STATE_CLOSED:
# Remove the disconnected peer.
_peers.erase(peer_id)
var code = peer.get_close_code()
var reason = peer.get_close_reason()
print("- Peer %s closed with code: %d, reason %s. Clean: %s" % [peer_id, code, reason, code != -1])When a client connects, this will print something similar to this:
Server started.
+ Peer 2 connected.
< Got text data from peer 2: Test packet ... echoingAdvanced chat demo
A more advanced chat demo which optionally uses the multiplayer mid-level abstraction and a high-level multiplayer demo are available in the godot demo projects under networking/websocket_chat and networking/websocket_multiplayer.