Introduction

Web applications should have the ability to acquire, manipulate, and pass data in a wide variety of forms, including as a sequence of data made available over time. The WHATWG Streams API specification defines the basic representation for streams of data, and programmatic ways to read and write streams of data and errors raised on those operations. This W3C spec had been defining a Streams API, but has been merged into the effort at WHATWG. Feedback made for the W3C spec has been incorporated into the WHATWG Streams API specification. Currently, the goal of this spec is for discussing and defining extensions to meet requirements specific to the browser environment.

The WritableStream interface defines a general protocol for data consuming APIs to communicate with data producing code. In these cases, the data consuming API, such as a decoder, provides a WritableStream for other applications to write to, enabling the decoder to begin decoding data as it becomes available.

The ReadableStream interface defines a general protocol for data producing APIs to communicate with data consuming code. This interface represents the potential for an infinite amount of data which are obtained over time and read once.

The WritableByteStream interface is extended version of WritableStream which has functionality for high performance binary data handling.

The ReadableByteStream interface is extended version of ReadableStream which has functionality for high performance binary data handling. As well as Blob, it might be worth providing a way to get a URL from which we can load data stored in a ReadableByteStream.

The example below demonstrates how to obtain a ReadableByteStream from XMLHttpRequest to begin playing a large video in readystate LOADING. The example takes the ReadableByteStream from a producer, XMLHttpRequest, and gives it to a consumer, the video tag.

function handler() {
  if (this.readyState == this.LOADING) {
    var rbs = this.response;
    var rbsURL = URL.createObjectURL(rbs);
    document.getElementById("placeToPlayMyVideo").src = rbsURL;
  }
}

var client = new XMLHttpRequest();
client.onreadystatechange = handler;
client.open("GET", "/myvideo");
client.responseType = "stream";
client.send();