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Streams

Thursday, October 30th, 2014

We're happy to announce the addition of the Streams Standard to the list of specs maintained by the WHATWG!

Streaming data shows up all over the web platform, and this new spec gives us a set of APIs for creating and interfacing with that data. We hope that streams will be a unifying primitive for I/O, much like promises (the previous spec I worked on) have become for asynchronicity.

The Streams Standard provides a basic set of primitives, namely readable streams, writable streams, and transform streams, which can be created directly by developers and by other parts of the web platform. For example, the Fetch Standard could expose request bodies as a writable stream, or response bodies as a readable stream. More generally, the platform is full of streaming abstractions waiting to be expressed as streams: multimedia streams, file streams, interprocess communication, and more benefit from being able to process data incrementally instead of buffering it all into memory and processing it in one go.

This work, of building streams into the web's APIs, has in many cases already begun. The W3C TCP and UDP Socket API provides an excellent example of a streams-based specification. We're also discussing how to integrate with fetch, service workers, media source extensions, and web audio—with more to come! Meanwhile, all the major browser vendors have expressed strong interest in or even begun implementation of the stream primitives.

Finally, I want to say a word about this spec's development model. The spec has been hosted on GitHub for over a year while it gestated, and has gathered a lively community around it of people willing to help us work through the often-tough design problems. Alongside the spec we have been developing a reference implementation ("polyfill") and a comprehensive test suite. We have a very active issue tracker, and have embraced practices like pull requests, branches, and continuous integration. It's been a fun journey to get the Streams Standard to a point where it's ready to join the august assembly at spec.whatwg.org, and I appreciate the WHATWG community for helping me along the way.

If you're hungry for more streams knowledge, please check out the spec; the introduction and model sections are especially accessible, and there are extensive examples. And while you're reading, feel free to file an issue or open a pull request if something could be improved!

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