web api interface
WebTransportDatagramDuplexStream
Secure context Available in workers
The WebTransportDatagramDuplexStream interface of the WebTransport API represents a duplex stream that can be used for unreliable transport of datagrams between client and server. Provides access to a ReadableStream for reading incoming datagrams, a WritableStream for writing outgoing datagrams, and various settings and statistics related to the stream.
This is accessed via the datagrams property.
“Unreliable” means that transmission of data is not guaranteed, nor is arrival in a specific order. This is fine in some situations and provides very fast delivery. For example, you might want to transmit regular game state updates where each message supersedes the last one that arrives, and order is not important.
Instance properties
incomingHighWaterMarkDeprecated- : Gets or sets the high water mark for incoming chunks of data — this is the maximum size, in chunks, that the incoming
ReadableStream’s internal queue can reach before it is considered full. See Internal queues and queuing strategies for more information.
- : Gets or sets the high water mark for incoming chunks of data — this is the maximum size, in chunks, that the incoming
incomingMaxAge- : Gets or sets the maximum age for incoming datagrams, in milliseconds. Returns
nullif no maximum age has been set.
- : Gets or sets the maximum age for incoming datagrams, in milliseconds. Returns
maxDatagramSizeRead only- : Returns the maximum allowable size of outgoing datagrams, in bytes, that can be written to a
WebTransportDatagramsWritableobtained viacreateWritable(), or the deprecatedwritableproperty.
- : Returns the maximum allowable size of outgoing datagrams, in bytes, that can be written to a
outgoingHighWaterMarkDeprecated- : Gets or sets the high water mark for outgoing chunks of data — this is the maximum size, in chunks, that the outgoing
WritableStream’s internal queue can reach before it is considered full. See Internal queues and queuing strategies for more information.
- : Gets or sets the high water mark for outgoing chunks of data — this is the maximum size, in chunks, that the outgoing
outgoingMaxAge- : Gets or sets the maximum age for outgoing datagrams, in milliseconds. Returns
nullif no maximum age has been set.
- : Gets or sets the maximum age for outgoing datagrams, in milliseconds. Returns
readableRead only- : Returns a
ReadableStreaminstance that can be used to read incoming datagrams from the stream.
- : Returns a
writableRead only Deprecated- : Returns a
WritableStreaminstance that can be used to write outgoing datagrams to the stream.
- : Returns a
Instance methods
createWritable()Experimental- : Returns a
WebTransportDatagramsWritableinstance that can be used to write outgoing datagrams to the stream.
- : Returns a
Examples
Writing outgoing datagrams
This code uses the createWritable() method, if it is supported, to get a WebTransportDatagramsWritable instance that can be used for writing data to the transport.
Otherwise, it falls back to the writable property Deprecated , which returns a WritableStream object that you can write data to using a writer instead:
const writableStream =
typeof transport.datagrams.createWritable === "function"
? transport.datagrams.createWritable()
: transport.datagrams.writable; // Deprecated and non-standard
const writer = writableStream.getWriter();
const data1 = new Uint8Array([65, 66, 67]);
const data2 = new Uint8Array([68, 69, 70]);
await writer.ready;
writer.write(data1);
await writer.ready;
writer.write(data2);
Reading incoming datagrams
The readable property returns a ReadableStream object that you can use to receive data from the server:
async function readData() {
const reader = transport.datagrams.readable.getReader();
while (true) {
const { value, done } = await reader.read();
if (done) {
break;
}
// value is a Uint8Array.
console.log(value);
}
}