RTCDataChannel.md

RTCDataChannel

Namespace: SpawnDev.SpawnJS.JSObjects.WebRTC
Inheritance: SpawnJSObject -> EventTarget -> RTCDataChannel
MDN Reference: RTCDataChannel

The RTCDataChannel class represents a bi-directional data channel between two peers in a WebRTC connection. Data channels can carry arbitrary data (text or binary) and support ordered/unordered delivery and configurable reliability. Created via RTCPeerConnection.CreateDataChannel() or received via the OnDataChannel event.

Constructors

Signature	Description
RTCDataChannel(SpawnJSObjectReference _ref)	Deserialization constructor.

Properties

Property	Type	Description
Label	string	The name of the data channel.
Ordered	bool	Whether messages are delivered in order.
Protocol	string	The sub-protocol in use.
ReadyState	string	Current state: "connecting", "open", "closing", "closed".
BufferedAmount	long	Number of bytes queued for sending.
BufferedAmountLowThreshold	long	The threshold at which OnBufferedAmountLow fires.
BinaryType	string	Binary data type: "arraybuffer" or "blob".
MaxPacketLifeTime	int?	Maximum time (ms) to attempt retransmission.
MaxRetransmits	int?	Maximum number of retransmission attempts.
Negotiated	bool	Whether the channel was negotiated out-of-band.
Id	int?	The channel's ID number.

Methods

Method	Return Type	Description
Send(string data)	void	Sends a text message.
Send(ArrayBuffer data)	void	Sends binary data as an ArrayBuffer.
Send(Blob data)	void	Sends binary data as a Blob.
Send(TypedArray data)	void	Sends binary data from a TypedArray.
Send(byte[] data)	void	Sends binary data from a .NET byte[].
Close()	void	Closes the data channel.

Events

Event	Type	Description
OnOpen	ActionEvent<Event>	Fired when the channel is open and ready to send/receive data.
OnClose	ActionEvent<Event>	Fired when the channel is closed.
OnMessage	ActionEvent<MessageEvent>	Fired when a message is received.
OnError	ActionEvent<RTCErrorEvent>	Fired when an error occurs.
OnBufferedAmountLow	ActionEvent<Event>	Fired when the buffered amount drops below the threshold.

Example

// Create a data channel
using var channel = pc.CreateDataChannel("file-transfer", new RTCDataChannelOptions
{
    Ordered = true,
    MaxRetransmits = 3
});

// Subscribe to events using named methods (required for proper cleanup)
channel.OnOpen += Channel_OnOpen;
channel.OnMessage += Channel_OnMessage;
channel.OnClose += Channel_OnClose;

// Monitor buffered amount for flow control
channel.BufferedAmountLowThreshold = 65536;
channel.OnBufferedAmountLow += Channel_OnBufferedAmountLow;

// Send binary data
byte[] binaryData = new byte[] { 0x01, 0x02, 0x03 };
channel.Send(binaryData);

// Send typed array data
using var float32Data = new Float32Array(new float[] { 1.0f, 2.0f, 3.0f });
channel.Send(float32Data);

// Clean up event handlers before disposal
channel.OnOpen -= Channel_OnOpen;
channel.OnMessage -= Channel_OnMessage;
channel.OnClose -= Channel_OnClose;
channel.OnBufferedAmountLow -= Channel_OnBufferedAmountLow;

void Channel_OnOpen(Event evt)
{
    Console.WriteLine($"Channel '{channel.Label}' opened");
    channel.Send("Hello from the local peer!");
    evt.Dispose();
}

void Channel_OnMessage(MessageEvent evt)
{
    var data = evt.Data;
    if (data is string textData)
    {
        Console.WriteLine($"Received text: {textData}");
    }
    evt.Dispose();
}

void Channel_OnClose(Event evt)
{
    Console.WriteLine("Channel closed");
    evt.Dispose();
}

void Channel_OnBufferedAmountLow(Event evt)
{
    // Safe to send more data
    evt.Dispose();
}