WebTransport: createUnidirectionalStream() method
The createUnidirectionalStream()
method of the WebTransport
interface asynchronously opens a unidirectional stream.
The method returns a Promise
that resolves to a WritableStream
object, which can be used to reliably write data to the server.
"Reliable" means that transmission and order of data are guaranteed. This provides slower delivery (albeit faster than with WebSockets) than datagrams
, but is needed in situations where reliability and ordering are important, like chat applications.
Note: This feature is available in Web Workers
Syntax
js
createUnidirectionalStream()
Parameters
None
Return value
A Promise
that resolves to a WritableStream
object.
Exceptions
InvalidStateError
DOMException
-
Thrown if
createUnidirectionalStream()
is invoked while the WebTransport is closed or failed.
Examples
Use the createUnidirectionalStream()
method to get a reference to a WritableStream
. From this you can get a writer to allow data to be written to the stream and sent to the server.
Use the close()
method of the resulting WritableStreamDefaultWriter
to close the associated HTTP/3 connection. The browser tries to send all pending data before actually closing the associated connection.
js
async function writeData() {
const stream = await transport.createUnidirectionalStream();
const writer = stream.writable.getWriter();
const data1 = new Uint8Array([65, 66, 67]);
const data2 = new Uint8Array([68, 69, 70]);
writer.write(data1);
writer.write(data2);
try {
await writer.close();
console.log("All data has been sent.");
} catch (error) {
console.error(`An error occurred: ${error}`);
}
}
You can also use WritableStreamDefaultWriter.abort()
to abruptly terminate the stream. When using abort()
, the browser may discard any pending data that hasn't yet been sent.
js
// ...
const stream = await transport.createUnidirectionalStream();
const writer = ws.getWriter();
// ...
writer.write(...);
writer.write(...);
await writer.abort();
// Not all the data may have been written.
Specifications
Specification |
---|
WebTransport # dom-webtransport-createunidirectionalstream |
Browser compatibility
BCD tables only load in the browser